Citation
Proceedings of the Third Annual No-Tillage Systems Conference

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Title:
Proceedings of the Third Annual No-Tillage Systems Conference theme, energy relationships in minimun tillage systems
Creator:
Gallaher, Raymond N
University of Florida -- Institute of Food and Agricultural Sciences
Conference:
Southeastern No-Tillage Systems Conference, 1980
Place of Publication:
Gainesville Fla
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The Institute
Publication Date:
Language:
English
Physical Description:
ix, 202 p. : ill. ; 28 cm.

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Subjects / Keywords:
Conservation tillage -- Congresses ( lcsh )
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bibliography ( marcgt )
conference publication ( marcgt )

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Includes bibliographical references.
General Note:
Cover title.
General Note:
"June 19, 1980."
Funding:
Electronic resources created as part of a prototype UF Institutional Repository and Faculty Papers project by the University of Florida.
Statement of Responsibility:
sponsored by Agronomy Department, Institute of Food and Agricultural Sciences, University of Florida ; editor and coordinator, Raymond N. Gallaher.

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Full Text
PROCEEDINGS OF THE THIRD ANNUAL
NO-TILLAGE SYSTEMS CONFERENCE
oaq
THEME:
ENERGY RELATIONSHIPS IN MINIMUM TILLAGE SYSTEMS
WAS
-SEARCH EXTENSION
Sponsored by Agronomy Department C. E. Dean, Chairman Institute of Food and Agricultural Sciences University of Florida Gainesville, Florida 32611
Editor and Coordinator Raymond N. Gallaher
June 19, 1980







CONTENTS
Title and Author(s) Page
Preface
Raymond N. Gallaher VI
Comments of the Vice-President of the Institute of Food and Agricultural Sciences.
K.R. Tefertiller VIII
Comments of the Dean for Extension
J.T. Woeste IX
Comments of the Dean for Research
F.A. Wood X
Pest Management Decisions in No-Tillage Agriculture
J. N. All 1
Minimum Tillage-One County Agent's View Point
J.A. Baldwin 7
Breeding Small Grains: Minimum Tillage and Energy Implications
R.D. Barnett, P.L. Pfahler, and H.H. Luke 9
Conservation of Energy in No-Tillage Systems by Management of Nitrogen
R.L. Blevins, W.W. Frye, and M.J. Bitzer 14
Double Cropping Soybeans Succeeding Soybeans in Florida
K.J. Boote 21
Weed Control Programs for No-Tillage Soybeans
B.J. Brecke 30
Deeper Rooting in Minimum Tillage to Conserve Energy
R.B. Campbell 33
Fuel Consumption and Power Requirements for Tillage Operations
R.P. Chromwell, J.M. Stanley, R.N. Gallaher, and D.L. Wright 37
Herbicide Tolerance and Wild Radish Contool in Lupine and Vetch
G.R. England, W.L. Currey, and R.N. Gallaher 42
Weed Control for No-Tillage Soybeans in Rye Straw
R.N. Gallaher and W.L. Currey 49
Subsoiling and Minimum Tillage of Corn on Florida Flatwood Soil
R.N. Gallaher and W.R. Ocumpaugh 54
III




CONTENTS CONTINUED
Title and Author(s) Page
Comparisons of Energy Requirements for Weed Control in Conventional and No-Tillage Soybeans
J.M. Goette, W.L. Currey, B.J. Brecke, M.B. Green, and R.C. Fluck 61
Are No-Tillage NHlticropping Production Methods Profitable for Florida Farmers?
D.L. Gunter, N.C. McCabe, and R.N. Gallaher 68
Alternative Tillage in Jefferson County, Florida
L.A. Halsey and Phil Worley 76
Minimum Tillage Demonstration Project Agricultural Conservation Program (ACP) 78
Betty Jones
Establishment of Legumes in Bahia Grass Sod I
R.S. Kalmbacher 86
Conservation Tillage Systems in Florida-SCS Viewpoint
J.D. Lawrence 92
Pest Insects as Affected by Tillage Methods in Soybeans,Corn, and Sorghum
Ki-Munseki Lema, R.N. Gallaher and S.L. Poe 97
No-Tillage in North Carolina
W.M. Lewis, A.D. Worsham, G.C. Naderman, and E.G. Krenzer 112
The Influence of Minimum Tillage on Populations of Soilborn Fungi, Endomyiorrhizal Fungi, and Nematodes in Oats and Vetch
D.J. Mitchell, N.C. Schenck, D.W. Dickson, and R.N. Gallaher 115
Seeding and Reseeding of Cool-Season Forages in North Florida
G.M. Prine 124
Subsoiling: Minimum Tillage and Energy Implications
F.M. Rhoads and D.L. Wright 130
Minimum Tillage of Corn in Perennial Sod: A Three-Year Study with Energy Implications
W.K. Robertson, R.N. GAllaher, and G.M. Prine 140
No-Tillage Versus Conventional Tillage Corn in Bahia Grass Sod with Soybeans Following
R.L. Stanley, JR. and R.N. Gallaher 152
No-Tillage in Florida From A Farmers Viewpoint
Danny Stephens 156
IV
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V
CONTENTS CONTINUED
Title and Author(s) Page
Postemergence Directed Spray Equipment and Calibration
D.H. Teem 165
Soil and Water Conservation Through Double Cropping
F.D. Tompkins, C.H. Shelton, and C.R. Graves 172
Soil Fertility and Its Relationship To Crop Production Cost in No-Tillage Systems
J.T. Touchton 180
Reducing Energy Inputs Into No-Tillage Systems
A.C. Trouce,Jr. and Carl A. Reaves 188
Effect of Plant Population on Yield, Disease, and other Parameters of Soybeans Planted No-Till and Conventionally
D.L. Wright, F.M. Shokes, and W.B. Tappan 196




PREFACE
Climatic conditions in Florida and the Southeast are such that
multicropping should be fully utilized to harvest the ENERGY FROM THE SUN and to meet the demand for agridultural products. Food and fiber production must increase to satisfy the needs of a rfpidly growing population in Florida and the Southeast and to help meet the needs created from national and world competition. -Producers must make better utilization of their farmland on a year-round production basis to offset increased costs of ENERGY inputs from fuel~machinery, chemicals, and fertilizer as well as increased cost due to inflation, land prices, taxes, labor, and interest.
Many multicropping systems can be more efficiently managed by utilizing no-tillage operations in crop production. The no-tillage method of producing crops consists of planting directly into an unprepared seedbed and the elimination of tillage operations through harvest. No-fillageoffers producers an opportunity to reduce erosion, conserve water, reduce labor, be timely in planting, reduce production cost, increase the probability of growing two or more crops per year on the same land(Multiple Cropping), and reduce FUEL use in crop production. The no-tillage practice has become more popular during recent years because of (a) the availability of planting equipment designed
to operate under unplowed stubble and/or mulched conditions, (b) the development of improved herbicide to control grass and broadleaf weeds, I
(c) the quality research conducted in recent years by agricultural scientists, (d) the educational efforts with field days, demonstrations, conferences, and shortcourses conducted by scientists in our state 3
University Cooperative Extension Services, and (e) of late, the spiriling cost of ENERGY is causing producers to take a closer look at the use of excess tillage. 1
We innitiated a coordinated program on Multicrpping Minimum Tillage Systems in Florida, beginning in 1976. Numerous faculty of the Institute of Food and Agricultural Sciences at various Agricultural Research I
Centers and the University of Florida at Gainesville, initiated multicropping and/or minimum tillage research studies and demonstrations. We are presently completing three and four years old studies and results are beginning to become available for Florida farmers to use. Scientists I
located throughout the Southeast are also involved in various aspects of no-tillage. Cooperative efforts among Universities and other Federal and state agencies are increasing so that "know how" is more readily accessible I
to our farmers.
This conference has been planned for extensive show-and-tell activities 5 by scientists, governmental agencies, seed companies, fertilizer industries, chemical industries, equipment companies, other companies and dealers and by farmers. The main objective is to transfer information available on no-tillage management to farmers and those who serve farmers with particular i emphasise on energy conservation.
I
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VII
Preparation for the "Third Annual Southeastern No-Tillage Systems Conference" has been a difficult task and several people and organizations deserve acknowledgement. I personally wish to extend special recognition to Mr. Rolland Weeks and his aAistants Mr. J. David Massey, Mr. Joseph K. McCoy and Ms. Suzanne Dyal for Mr. Week's leadership and the hard work and talent they all have provided to make the conference a success.
Miss Marilyj7L. Copeland is appreciated for her time devoted particularly to the typing, t~&1phone calls and headaches associated with these proceedings. I also wish to express appreciation to Mr. Bruce A. Fritz, Ms. Edwina L. Williams and Ms. A.D. Staples for their assistance with messages and various other problems.
The Robinson Family of Williston, Mr. J. Raymond and his father Mr. R.S. Robinson deserve special recognition for aiding in carrying out this conference on their farm. Mr. Danny Stephens is acknowledged for furnishing equipment and other help in making this conference a success.
Acknowledgements are extended to all faculty, administrators, students, technical assistants, industry personnel, governmental agencies, and farmers who have supported our efforts. Listed below are others who have provided extensive support for us to carry out this conference:
Chevron Chemical Corporation W.O. McCurdy and Sons Seed Co.
CIBA Geigy Corporation Funks Seeds International
BASF Wyandotte Corporation E.I. DuPont De Nemours and Co.
Brown Mnaufacturing Co. FMX Store Treton, FL.
DeKalb Agresearch, Inc. Hatch Enterprises Bradford, FL.
Florida Feed And Seed Company Swick Farm Supply High Springs, FL.
FMC Corporation J.C. Harden and Sons Banks, Alabama
Gold Kist Inc. Fauver Harvesting Service Sanford, FL.
International Minerals and Chemical Co. Mr. Mont Brook Morriston, FL. Kaiser Agricultural Chemical Co.
The Nitrogen Co., Inc.
Pioneer Hi-Bred International, Inc.
Coker's Seed Co.
RAYMOND N. GALLAHER
Coordinator and Editor




UNIVERSITY OF FLORIDA
IFAS INSTITUTE OF FOOD AND AGRICULTURAL SCIENCES
GAINESVILLE, FLORIDA 32611
OFFICE OF THE VICE PRESIDENT
FOR AGRICULTURAL AFFAIRS
1008 MCCARTY HALL TELEPHONE: 904-392-1971
NO-TILLAGE SYSTEMS FOR THE THIRD ANNUAL SOUTHEASTERN NO-TILLAGE SYSTEMS CONFERENCE
The economic strength of our nation has depended heavily upon a
cheap and readily available energy supply. The agricultural sector has,
over the last fifty years, also become heavily energy dependent. The short supply and high cost of energy can have a devastating effect on our ability to continue producing the safe, nutritious and reasonably
priced food supply needed by our citizens and for export. The escalating cost of production inputs and high interest rates are causing many
farmers today to consider whether to contine farming or not.
We at the University of Florida's Institute of Food and Agricultural
Sciences (IFAS) are addressing energy problems through extensive "lowenergy technology" research, extension and education programs. Florida is taking a leadership role nationally in the development of low-energy
technology, and IFAS is heavily committed to this effort.
New technology usually takes time to develop. However, our multicropping minimum tillage program is one example where we have low-energy technology ready for the farmer's use. This "No-Tillage Systems Conference" is designed to show the technology available to our farmers and
the management practices that will work today. On behalf of IFAS, I
welcome you to this "Third Annual Southeastern No-Tillage Systems
Conference". We trust that you will gain information that will aid you I
in lowering energy inputs while maintaining your production needs and
goals. Best wishes.
K. R. Tefertiller
Vice President for
Agricultural Affairs
I
I
I
COL.lGI. F AGRICULTURE AGICULTURAl, Lt XPErIMEINT SiTA rIONS COOPERATIVE EXTENSION SERVICE
SCHOOL OF FOREST RESOURCES AND CONS IRVATION GI.NTERC FOR TROPICAL AGRICULTURE
I he InIsiIs I1 FoI dill I Agrclil t ur ill Scienc iis )Ill Equal Li mpl y m,!I I Oppol tui ty Athimative Action Employer authorized to provide research,
dentillonal information and (other services only to individuals and institutions that function without regard to race, color, sex, or national origin. I




FLORIDA COOPERATIVE EXTENSION SERVICE UNIVERSITY OF FLORIDA
INSTITUTE OF FOOD AND AGRICULTURAL SCIENCES I FAS
COOPERATIVE EXTENSION SERVICE AGRICULTURAL. EXPERIMENT STATIONS
TEACHING RESEARC14 EX SCHOOL OF FOREST RESOURCES AN 0 CONSERVATION COLLEGE OF AGRICULTURE REPLY TO
STATEMENT ON NO-TILLAGE SYSTEMS FOR THE THIRD ANNUAL SOUTHEASTERN NO-TILLAGE SYSTEMS CONFERENCE
No-tillage systems, like many of the practices developed and
demonstrated by IFAS, are part of our effort to insure that
Florida Agriculture remains a competitive and compatible
industry. No-tillage systems are a good example of technology
being applied to reduce cost of production, conserve energy inputs and enhance our national drive toward greater energy
independence and reduce both topsoil and water losses..
The success of our farmers in squeezing out production costs
is the major reason the American public has paid so little for their food supply. Advancement of no-tillage technology should help to insure continued increases in productivity on our farms as well as the unequal contribution of the farmer to the overall
productivity in our country and the world.
We believe that highly reliable no-tillage systems will be essential to Florida Agriculture. Florida's dependence on
petroleum energy under current technology demands our unconditional commitment to both immediate advances in productivity and material reductions in our reliance on petroleum energy.
John T. Woeste
Dean for Extension
Ix
The Institute of Food and Agricultural Sciences is an Equal Employment Opportunity Affirmative Action Employer authorized to provide research, educational information and other services only to individuals and institutions that function without regard to race, color, sex, or national origin.
COOPERATIVE EXTENSION WORK IN AGRICULTURE AND HOME ECONOMICS, STATE OF FLORIDA, IFAS, UNIVERSITY OF
FLORIDA, U. S. DEPARTMENT OF AGRICULTURE, AND BOARDS OF COUNTY COMMISSIONERS COOPERATING




UNIVERSITY OF FLORIDA
IFAS INSTITU-rE OF FOOD AND AGRICULTURAL SCIENCES
GAINESVILLE, FLORIDA 32611
FLORIDA AGRICULTURAL EXPERIMENT STATIONS June 4, 1980
OFFICE OrF THE DEAN FOR RESEARCH
1022 McCARTY HALL TI:l F-PHONE: 904-392-1784
STATEMENT OF NO-TILLAGE SYSTEMS FOR THE THIRD ANNUAL SOUTHEASTERN NO-TILLAGE SYSTEMS CONFERENCE
M'ltiple cropping and minimum tillage are different but important approaches to
increasing the productivity per unit of land and at the same time minimizing the I
amount of energy required per unit of productivity. Neither approach to production is ,ew, but each has assumed significantly greater importance in view of the energy
environment in which we live and the need to conserve energy wherever possible. The
integration of multiple cropping and minimum tillage practices has even greater
potential for increased production and improved efficiency in the utilization of
energy. Consequently, the Institute of Food and Agricultural Sciences of the
University of Florida has made significant increases in research programs in these
two iffportant areas.
Ii-Y multiple cropping/minimum tillage research program is statewide with emphasis 3
on vegetable and agronomic succession cropping systems and sod seeding interplant
systems. Variables in this array of studies include tillage practices, weed control
techniques, pest management techniques and strategies, irrigation, fertility, and va-rious crop sequences. The results of such investigations are made available to agri'ultural industries in the state through a series of field demonstrations and
research and extension publications. 3
Multiple cropping/minimum tillage research is truly a muntidisciplinary research
effort and as a consequence involves scientists from the commodity and discipline
departments within IFAS. In addition, it does and will continue to involve very close I
cooperation between and among scientists located in Gainesville with scientists located at out-state research centers; our system of out-state research centers
provides an ideal setting for the development and evaluation of multicropping/minimum
tillage management systems. I am pleased with the research program that has been
developed in this important area and am confident that with results of these and
other related research programs, Florida's agriculture will continue to be competitive. I
It it a pleasure to have you join us in the Third Annual Southeastern No-Tillage Syste'ms Conference and to have the opportunity to provide to you first-hand some
of te significant results of our research in this area. I
F. Aloysius Wood I
Dean for Research
I
COLLEGE OF AGRICULTURE AGRICULTURAL EXPERIMENT STATIONS COOPERATIVE EXTENSION SERVICE
SCHOOL OF FOREST RESOURCES AND CONSERVATION CENTER FOR TROPICAL AGRICULTURE
The Institute of Food and Agricultural Sciences is an Equal Employment Opportunity Affirmative Action Employer authorized to provide research,
educational information and other services only to individuals and institutions that function without regard to race, color, sex, or national origin.




PEST MANAGEMENT DECISIONS INNO-TILLAGE AGRICULTURE
* J. N. ALL
No-tillage (NT) systems involving corn are becoming increasingly popular in I the South because of the advantages apparent with these operations. NT is
especially useful in various types of multi-crop systems that take advantage of the Southern resource of a long growing season. Non-continuous types of I NT in which some form of tillage is utilized in a multi-crop sequence are
most prevalent. Since corn often is planted later than normal in these
systems, it may be subjected to greater infestations by pests. Continuous I NT procedures are not as common in the South and usually are associated
with sloping terrain with high erosion potential. It is important to
distinguish between the two types of NT in a discussion of pest potential
because the ecosystems undoubtedly differ greatly. Thus, unless otherwise specified the present discussion is concerned with non-continuous type of
NT.
I The insect complex attacking corn in the South causes millions of dollars in
damage annually. For example, during 1976 in Georgia insect losses and cost
of control in conventionally tilled (T) corn exceeded $14 million, while I losses associated with virus diseases transmitted by insects was ca. $0.2
million (Suber and Todd 1980). Economic impact of pests in NT are not
available, but research indicates that most problems are comparable to T
3 systems (All and Gallaher 1976).
Much of the present discussion is based on research conducted over the past 6 years in over 50 experiments in Georgia in which various NT systems Were Compared directly with T cropping. The experiments were located in 6 'areas
representing the major edaphic and climatic areas of Georgia. In the tests
all cropping practices (e.g. irrigation, planting date, subsoiling, insecticide, I hybrids, herbicides, cropping sequence) were the same in either tillage system
and the only difference was the tillage operation in T plots. Insect populations were quantified using standard sampling procedures. Also
observations of pest problems were made in farmers' fields and a survey was
conducted of extension personnel, commercial pest managers, pesticide and agricultural equipment distributors, and seed company representatives to
3 assess their views on pest potential in Southern NT systems.
Soil Insects Ecosystems are undoubtedly greatly different in NT and t systems, and the variation is probably highest near the soil surface due to the presence I of debris from former crops in NT. These conditions can have variable effects
on soil insects.
The lesser cornstalk borer (LCB), Elasmopalpus lignosellus (Zeller), i's a
polyphagous insect whose outbreaks in T corn are usually associated with
droughty soil conditions (Dupree 1965). LCB infestations are substantially
J. N.' All is Associate Professor of Entomology, Department of Entomology,
3 University of Georgia, Athens, Georgia 30602.




2
reduced in NT systems as compared to T systems (All and Gallaher 1977). This has been observed in over 30 experiments over a 6 year period and has been observed in growers' fields. All and Gallaher 1977 pointed out that higher soil moisture occurred in NT than T systems and proposed this as a factor inhibiting survival of LCB in NT. Later research indicated that a behavioral response of LCB is involved. Movement of radiolabeled larvae in relation to corn seedlings was distinctly different in NT than in T. Larvae released 20 cm from corn seedlings quickly located the plants in the T system; seedlings in NT systems were not located for up to 7 days after release (Cheshire et al. 1977, Cheshire and All 1978).
The billbug, Spenophorus callosus Oliver, feeds on various weeds, especially nutgrass, Cyperus rotundus L., in the larval stage and attacks corn only as adults. Overwintering adults migrate into corn fields from weeded areas and may cause extensive damage, especially in fields planted early in the season (Morgan and Beckham 1960). S. callosus produces damaging infestations in NT corn, and research indicates that problems can be greater than in T systems. In a recent experiment near Midville, Ga., S. callosus damage was 32.1 infested plants/100 m row in NT as compared to 19.0 infested plants in the T plots. The field had a moderate infestation of nutgrass that was poorly controlled with planting time applications of herbicides and the higher I
billbug populations were associated with the weed. Insecticide applications at planting time (Durant 1975, All and Jellum 1977) and after plants emerge (All and Jellum 1977) control S. callosus infestations in T systems; these methods also are effective in NT systems (J. All unpublished data).
Other soil insects such as the Southern corn rootworm Diabrotica undecimpunctata howardi Barber, seedcorn maggot Hylemya platura (Meigen), wireworms Melanotus spp., white fringed beetle Graphognathus spp., cutworms Agrotis spp. larvae have not developed quantifiable populations in experimental plots to assess their biopotential in NT systems. Also no reports of major infestations of these insects were expressed by the persons surveyed. However, damage to corn by these insects must be of concern to entomologists, especially in continuous NT systems where soil habitats are not periodically disturbed by tillage operations.
Whorl Feeding Insects Important insects that infest the seedling stage of corn (not discussed as soil insects) in the South include the fall armyworm Spodoptera frugiperda (J. E. Smith, armyworm Pseudaletia unipuncta (Haworth), corn earworm Heliothis zea (Boddie), European corn borer Ostrinia nubialis (Hubner), and the Southwestern corn borer Diatraea grandiosella (Dyar). Observations of all these insects in Georgia indicate that greatest damage can be anticipated in late corn plantings such as certain multi-crop systems involving NT (All and Gallaher 1976). I
Infestations of fall armyworms are a major threat to corn in NT multi-crop systems and are a factor that may limit the potential of certain of these systems in the South. Research indicates that tillage systems have little I
impact on development of fall armyworm infestations (All and Gallaher 1976). Close inspection of corn in experiments comparing NT and T systems at various planting dates demonstrated that heavy infestations often occur in both cropping systems planted after mid-May. Oviposition and larval populaLions on 2-4 leaf stage seedlings developed more rapidly in T plots, but populations
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and damage were similar in 5-leaf stage plants. Yield losses were comparable in either system. Efficacy of foliar insecticides was similar in either tillage system (J. All unpublished data).
Severe armyworm damage has been reported in late planted NT systems (Wrenn 1975) and damage from the other whorl feeders should be of concern in certain cases. However, our research indicates that the damage potential of these insects is not enhanced in NT as compared to T.
Stalk and Ear Feeding Insects Many insects that attack these growth stages in the South are also major pests in Northern states. However, their reproductive potential often is enhanced in the warmer Southern climate. For example, first generation European corn borer damage early planted corn while second and third generation larvae infest corn of later planting dates. Our research indicates that European corn borer infestations are similar in NT and T systems. However, infestations were increased in late plantings and these often are associated with NT practices in multicropping sequences. We also noted a reduction in the number of infested and lodged plants in irrigated plantings (both NT and T) as compared to nonirrigated plants (All and Gallaher 1976). Low infestations of Southwestern cornstalk borers were observed in Northwest Georgia during 19761979. Whorl feeding and stalk borer damage were similar in either tillage system (J. All unpublished data).
We have observed corn leaf aphid, Rhopalosiphum maidis (Fitch), infestation of corn tassels in NT and T plots. In two experiments, extensive sampling in fields with moderate johnsongrass populations (significantly higher in NT than T) revealed that aphid colonization4of corn tassels was higher in T (4.0 x 10 colonies/ha) than NT (2.7 x 10 colonies/ha) plots. However, many johnsongrass plants had colonies and if these are coupled with the aphid populations on corn, the overall Rumber of colonies in NT was 3.5 x 10 colonies/ha as compared to 4.5 x 10 /ha in T. Thus in this case, the increased plant diversity of NT had a dilution effect on an insect population infesting corn. In certain experiments substantially higher populations of a spittle bug, Prosapia sp, have been observed in NT as compared to T plots. However, the numphal feeding on brace roots caused no apparent damage to plants.
Corn earworm and fall armyworm infestations in corn ears in NT paralTels damage in T systems. Populations of both species were greater in plantings associated with multi-cropping and delayed corn planting dates. Damage by fall armyworm is especially severe in late planted corn with as many as 6 larvae causing complete destruction of some ears. Sampling indicated that damage was reduced in irrigated as compared to non-irrigated plots in both NT and T (All and Gallaher 1976).
Other insects associated with corn ears prior to harvest include sap beetles (Nitidulidae), maize weevil complex (Sitophilus spp.), Tenebrionidae, and Angoumois grain moth (Sitotroga cerealella (Oliver)), and these are serious problems in the South. Infestations initiated in the field by these species increase in stored grain (Floyd 1971). Also, these pests may be implicated in distributing grain-infesting fungi such as Aspergillus flavus that




4
produce mycotoxins in stored grain. Field infestations of certain of the stored grain insects may be increased in certain NT systems where corn is grown in the stubble of small grains. These insects are found in unharvested grain and data suggests that populations move into corn prior to harvest (J. All unpublished data).
Heavy populations of the ring-legged earwig, Euborellia annulipes (Lucas), were observed in NT corn ears; significantly more infested ears were sampled in NT plots (All and Gallaher 1976). These insects are not normally considered pests of corn, but they can produce damage to grain. Feeding near the tip of ears on the basal portion of the pericarp of kernels loosens the grain so that it is easily detached. All life stages were observed and as many as 10 individuals were counted in ears.
Epidemiology of Corn Virus Diseases Research indicates that two virus diseases, maize chlorotic dwarf (MCD) and maize dwarf mosaic (MDM), are greater in certain NT systems (All et al. 1977, 1980). Leafhoppers transmit MCD in corn; the blackfaced leafhopper, Graminella nigrifrons (Forbes), is a major vector (Nault et al. 1973). Several aphid species transmit MDM, including the corn leaf aphid (Williams and Alexander 1965).
The epidemiology of the diseases is complicated by the fact that both viruses infect a variety of grasses including weeds (e.g. large crabgrass, Digitaria sanguinalis (L). Scop., and johnsongrass, Sohum halepense (L.) Pers.) and small grains (e.g. winter wheat, Triticum aestivum L. Nault et al. 1976). Johnsongrass is the only known perennial host of the pathogens and in many areas it is an important factor in the spread of disease by acting as a reservoir of inoculum for vector transmission to corn (Damsteegt 1976).
We found that MCD and MDM were enhanced in NT as compared to T when johnsongrass was poorly controlled by the herbicides paraquat and atrazine (All et al. 1976). Data from these and other studies suggests that early season control of johnsongrass is very important in reducing disease in corn. Severity of the diseases is greater to young plants (Scheifele 1969), and thus the presence of even low populations of johnsongrass in fields when corn germinates greatly increases early season transmission by vectors. Recent tests showed that the herbicide glyphosate effectively controls johnsongrass in CT with corresponding reduction in disease (J. All unpublished data).
Optimum pest management of MCD and MDM involves integration of several control strategies to suppress the various factors involved in spread of the diseases (All et al. 1980). Vectors of MCD are susceptible to systemic insecticides (e.g. carbofuran) and hybrids are available that have disease resistance (Kuhn and Jellum 1975, Pitre 1968, Kuhn et al. 1975, All et al. 1976). Use of a resistant hybrid with a systemic insecticide was effective in controlling leafhoppers and decreasing MCD in NT. Grain yield was increased by up to 2333 kg/ha (All et al. 1977). Recent research in NT systems showed that an integrated chemical control approach using a systemic herbicide (glyphosate) to control johnsongrass plus a systemic insecticide (carbofuran) was highly effective (J. All unpublished data).




1 5
In summary, insect potential in NT systems in the South varies with the species involved and the type NT method. In general, non-continuous NT systems that have some form of tillage operation within a 1 or 2 year cropping sequence do not appear to develop greater insect infestations than T systems planted at the same time. However, certain insects such as billbugs produce greater damage in NT and concern must be shown for corn virus disease problems in NT systems where johnsongrass populations exist. Conversely, NT has control potential for lesser cornstalk borer. Obviously the environment that develops in NT systems differs greatly from T cropping, and the influence of these ecosystems on the biology of pest insects must be studied on an individual basis. Research indicates that standard control methods can be used in NT systems, but increased effort is needed in refining chemical application methodology for NT. Also, efforts in developing integrated pest management systems need to be expanded for NT.
REFERENCES
1. All, J.N., and R.N. Gallaher. 1976. Insect infestations in no-tillage
corn cropping systems. J. Ga. Agric. Res. 17:17-9.
2. All, J.N., C.W. Kuhn, and M.D. Jellum. 1976. The changing status of
corn virus diseases: potential value of a systemic insecticide. J. Ga.
Agric. Res. 17:4-6.
3. All, J.N., C.W. Kuhn, M.D. Jellum, R.N. Gallaher, and R.S. Hussey. 1976.
Vector dynamics and epidemiology of maize chlorotic dwarf in minimum
tillage and conventional tillage cropping. XV International Congress of
Entomology. August 1976.
4. All, J.N., and R.N. Gallaher. 1977. Detrimental impact of no-tillage
corn cropping systems involving insecticides, hybrids, and irrigation on lesser cornstalk borer infestations. J. Econ. Entomol. 70:361-5.
5. All, J.N., and M.D. Jellum. 1977. Efficacy of insecticide-nematocides
on Sphenophorus callosus and phytophagous nematodes in field corn.
J. Ga. Entomol. Soc. 12:291-97.
6. All, J.N., C.W. Kuhn, and M.D. Jellum. 1980. Control strategies for
vectors of virus and virus-like pathogens of maize and sorghum. Chp.
National Bull. Virus and Virus-like Pathogens of Maize and Sorghum. S-70
Tech. Comm. Virus and Virus-like Pathogens of Maize and Sorghum. In press.
7. Cheshire, J.M., Jr., Judith Henningson, and J.N. All. 1977. Radiolabeling lesser cornstalk borer larvae for monitoring movement in soil
habitats. J. Econ. Entomol. 70:578-80.
8. Cheshire, J.M., Jr., and J.N. All. 1978. Monitoring lesser cornstalk
borer larval movement in no-tillage and conventional tillage corn systems.
J. Ga. Agric. Res. 21:10-4
9. Damsteegt, V.D. 1976. A naturally occurring corn virus epiphytotic.
Plant Dis. Rept. 10:858-61.




10. Dupree, M. 1965. Observations on the life history of the lesser
cornstalk borer. J. Econ. Entomol. 58:1156-7.
11. Durant, J.A. 1975. Southern corn billbug (Coleoptera: Curculionidae)
control on corn in South Carolina. J. Ga. Entomol. Soc. 10:287-91.
12. Floyd, E.H. 1971. Relationship between maize weevil infestation in
corn at harvest and progressive infestation during storage. J. Econ.
Entomol. 64:408-11.
13. Kuhn, C.W., and M.D. Jellum. 1970. Evaluations for resistance to
corn stunt and maize dwarf mosaic diseases in corn. Ga. Agric. Exp.
Stn. Res. Bull. 82. 37 p.
14. Kuhn, C.W., and M.D. Jellum. 1975. Disease evaluation of commercial
hybrids. Ga. Agric. Exp. Stn. Res. Pap. 199. Pages 34-35.
15. Morgan, L.W., and C.M. Beckham. 1960. Investigations on control of
the southern corn billbug. Ga. Agr. Exp. Stn. Mimeo. Series N.S. 93.
9p.
16. Nault, L.R., W.E. Styer, J.K. Knoke, and H.N. Pitre. 1973. Semipersistent transmission of leafhopper-borne maize chlorotic dwarf
virus. J. Econ. Entomol. 66:1271-3.
17. Nault, L.R., D.T. Gordon, D.C. Robertson, and 0.E. Bradfute. 1976.
Host range of maize chlorotic dwarf virus. Plant Dis. Rept. 60:374-7.
18. Pitre, H.N. 1968. Systemic insecticides for control of the blackfaced leafhopper, Graminella nigrifrons, and effect on corn stunt
disease. J. Econ. Entomol. 61:765-8.
19. Scheifele, G.L. 1969. Effects of early and late inoculation of
maize dwarf mosaic virus strain A and B on shelled grain yields of
susceptible and resistant maize segregates of a three-way hybrid.
Plant Dis. Rept. 53:345-7.
20. Suber, E.F., and J.W. Todd. (Eds). 1980. Summary of economic losses
due to insect damage and costs of control in Georgia, 1971-1976.
Univ. Ga. Sp. Publ. 7:8-10.
21. Williams, L.E., and L.J. Alexander. 1965. Maize dwarf mosaic, a new
corn disease. Phytopathology. 55:802-4.
22. Wrenn, E. 1975. Armyworms launch heavy attack on many corn fields in
Virginia. S.E. Farm Press. July 2, 1975. p. 5, 28.




MINIMUM TILLAGE ONE COUNTY AGENT'S VIEWPOINT
JOHN A. BALDWIN1
I Each year in Levy County, numerous acres planted to corn and other
crops are damaged or destroyed by high winds and blowing soil traveling.
across young stands of agronomic and vegetable crops. In some years,
soil erosion due to wind not only damages crops by "sand blasting" but
*at times even reduces herbicidal activity by disturb ing treated preemergence areas.
*Our deep sandy soils also lend themselves to leaching of nutrients as
well as compaction problems which potentially restrict root growth.
Gontinous tillage of row crop land by discing, harrowing and plowing
have created serious compaction problems in some of our deep sandy I soils at depths of six to twelve inches. Evidence of this has been
demonstrated by subsoiling two to three inches below this compacted
* zone and comparing plant growth and yield to conventionally tilled
In essence, as a County Agricultural Agent, it is important to keep
abreast of the latest technology and innovations in cropping systems I and tillage equipment. Inflationary times and increasing fuel costs
have increased the unit cost of production. Methods are needed to
reduce unit costs while maintaining or increasing current production I to make row crop production economical. Over production may create
marketing problems by reducing prices paid to growers, but it will be
uto producers to limit or restrict the acreage planted in order to
ifunesupply and demand. Economical and efficient production
practices are needed to maintain an economically sound agriculture
for Florida.
I To utilize minimum tillage, a producer must evaluate his own set of
conditions on his farm. Soil types, crop rotations, managerial abilities and other resources must all be evaluated.
The major advantages of minimum or reduced tillage have been demon-, strated to be; reduction of soil erosion, energy conservation, less I soil compaction, improved timing of crop establishment and planting
and in some instances, reduced machinery investment.
Some major disadvantages have also been observed. When corn is planted
in February or possibly Early March, soil temperatures may remain
lower during extended periods when a mulch system of minimum tillage
is used. Gold, wet soils may inhibit germination or early season root I growth. Insects, particularly soil insects such as cutworms, may be
more prevalent when heavy mulches of winter cover crops are used.
Also, producers will need to put their best managerial ability togeth-r er because there is less room for error under minimum tillage systems., particularly under mulch systems of minimum tillage. More reliance is
John A. Baldwin is County Extension Director II, Levy County, FloridaI Cooperative Extension Service, Post Office Box 218, Bronson, Florida
I 7




81
needed on herbicides for weed control programs. Proper liming of soils for optimum herbicide activity, timing of spray applications, proper calibration of equipment and the potential use of directed sprays need
to be included in the management plan.
Producers should be cautioned to start on a small scale until sufficient experience is gained. They should also attend shortcourses, seminars,I demonstrations and field days to see and learn of multi-cropping, minimum tillage systems.
It is a package approach. We do not want to plant into a weed field. Plan through your County Extension Agent before implementing mimimum tillage practices. A management plan to fit your particular farm and resources will be needed. Planning before implementation of new farmingI methods reduces chances of failure and insures proper scheduling of production activities. Calling your County Agent when problems occur because of poor planning often results in no recourse for a solution. The croppingU
system and method of tillage should be well planned and fit to the individual farm and management regime. The planting and management of the succeeding or previous crop may be just as much or more important than the current crop being grown under minimum tillage methods. Subsoiling may not be needed in all instances, and fields should be inspected as to need for subsoiling prior to planting. The subsoiling will require more fuel and horsepower than doing strictly no-till plantings. ProperI
weed identification and mapping of fields are extremely important in the selection of proper herbicides for a given situation. A working knowledge of minimum tillage practices is needed by County Agents. ItI
is essential that the agent make available to the producer the most current information on minimum tillage.
Weather conditions affect our yields regardless of the cropping systemI being used. The weather causes our greatest risk in row-cropping today. We cannot control weather patterns but the use of minimum tillage in many situations may help insure better growing conditions and reduceI adverse effects such as soil erosion, leaching of nutrients, inadequate moisture at planting time, drought stress of crops, labor problems and time.
As multiple cropping systems are put into practice by producers, more intense use of available land will occur. As energy costs increase, minimum tillage systems will fit more and more into the picture of modern day agriculture.
Minimum Tillage acreage has increases since 1978, in Levy County. Corn,
Soybeans and Grain Sorghum have been planted following winter rye and the prior years' crop residues by minimum tillage methods. Several thousand acres of pines have been clear cut in the past three years.I This will increase the potential of crop damage by wind erosion. Also, energy costs are affecting our ability to irrigate economically. Minimum tillage practices should help to reduce both wind erosion and soil moisture losses. Again, we must learn to fit this system of cropping toI our land and management, keep current on production practices, and remember that a total management plan is needed to insure the best use
of oeanftal. and other resources.




BREEDING SMALL GRAINS:
MINIMUM TILLAGE AND ENERGY IMPLICATIONS
R. D. BARNETT, P. L. PFAHLER, AND H. H. LUKE
I Wheat, oats, and rye along with the clovers and ryegrass are used as the
winter annual components of many multiple cropping systems commonly used
in the southeastern United States. They can be used as forage or grain I crops, green manure, and cover crops, or as a weed suppressing and
moisture holding mulch for summer row crops. Small grains require relatively
low levels of input in the way of energy requiring fertilizers and pesticides.
They are able to utilize much of the nitrogen fixed by leguminous summer
annuals, such as soybeans and peanuts, that might be lost by leaching during
the winter months. They also are very efficient in the utilization of residual
fertilizers which have been applied to row crops. Small grains do require
fertilization but not nearly as much as most summer annual grass or vegetable
Small grains do not require nematicides or insecticides because these pests
are relatively inactive during the growing season of the small grains. Also,
they do not require herbicides because very few winter weeds are able to
compete with them.
There are three methods of establishing a small grain crop: 1) prepared
seedbed, 2) sod seeding into permanent pasture, and 3) aerial seeding into I standing crops. The prepared seedbed method is the best and most widely
used, though more costly. The major problem in sod seeding small grains into summer grasses is that the summer grass is vigorously growing at the I ideal planting time for small grains. The summer grass must be grazed
very closely in order to obtain an acceptable stand of small grains. Sod
seeding is usually more successful with ryegrass or clover since their growing season does not overlap that of the perennial grass.
Aerial seeding is growing in popularity because it is cheaper, easier, and faster than conventional methods and can be done into a number of crops
I but works best in soybeans. The seed are disseminated from the air just as
the soybean leaves start to turn yellow, then the leaves fall covering the
seed. This works very well with adequate moisture but does not work well During dry falls. It works best with the later-maturing soybeans since their
leaf fall comes at the optimum time to seed small grains. This system is used
quite extensively in the southeast for seeding rye and ryegrass for winter3 grazing.
Diseases are a major limiting factor to small grain production in Florida
because the mild winters are extremely favorable for the maximum developI ment of plant diseases. Minimizing the losses to disease requires an
integrated approach that includes crop rotation, deep plowing, timely planting, variety selection, and fungicides. Crop rotation is especially important
R. D. Barnett, Associate Professor of Agronomy, Agricultural Research and
Education Center, Route 3 Box 638, University of Florida, Quincy, Florida
32351. P. L. Pfahler is Professor of Agronomy, Agronomy Department, UniI versity of Florida, Gainesville, Florida 32611; H. H. Luke is Professor of
Plant Pathology, SEA, U. S. Department of Agriculture, Plant Pathology
Department, University of Florida, Gainesville, Florida 32611.
9




10
in the case of wheat because several serious diseases build up if wheat is grown on the same area year after year. Turning the soil, although rather expensive and requiring high energy, would help reduce the initial inoculum of several wheat diseases if wheat had recently been grown on the same area. This practice reduces weed problems for the following summer crop since many of the weed seed are buried. Also, any potential problem that might be caused from a herbicide used on the previous summer crop would be reduced since the herbicide residue would be diluted into a larger volume of soil.
Fungicide seed treatments are a cheap way to avoid potential germination problems. If the seed are not of top quality, seed treatment will often improve germination and insure a better stand. Seed treatments are especially useful when planting in early fall when temperatures are high and seedling diseases are active. Seed treatments are helpful late in the season when the temperatures are rather low and germination is slow. When the seedlings are below the soil surface over a long time period, they are more susceptible to attack by seedling diseases.
Wheat is the most versatile of the small grains. It can be used as a grazing, silage, hay, greenchop, green manure, or mulch crop. It can also be used as a feed grain and most importantly as a food crop. The type of wheat grown in the southeast is soft red winter wheat. The flour from this type of wheat is not used in bread but is used in cakes, cookies, donuts, crackers, etc. High quality soft red winter wheat should be low in protein and have a high test weight. Excess nitrogen fertilization will cause the protein content to be too high and results in poor quality wheat.
Diseases are one of the major limiting factors in wheat production. Leaf rust, septoria glume blotch, and powdery mildew are all capable of causing substantial yield losses and must be controlled either by the use of resistant cultivars or fungicides. It is important in wheat production to adopt new cultivars as soon as they become available because after a few years new races of disease organisms develop and cause severe damage to the new cultivars.
Increased wheat acreage in the southeastern United States has resulted in sharp yield reductions caused by lack of rotation and seedborne infestation by Septoria nodorum (13). Our observations and those of others indicate that infested seeds are a major source of inoculum (10, 13) that might be reduced by foliar fungicide applications (9) and by seed treatments. Other work with fungicides has shown that yield increases may be obtained when fungicides are used properly (3, 4, 8).
Planting late in the season reduces the damage caused by several important pest of wheat, septoria, powdery mildew, and hessian fly. Some of the new early-maturing cultivars of wheat perform well from later planting and they fit into the multiple cropping systems better than the later-maturing cultivars.
All small grains provide excellent winter pasture but there are marked differences among species and cultivars in their forage production. Under a monthly clipping schedule, rye yields considerably more forage than the other smallgrains (11). When used as a silage or hay crop, oats perform better




than the other small grains (2). Rye produces more forage early in the season, whereas oats and wheat produce most of their forage later in the season.
There are also differences between cultivars in their season of forage production. For example, Florida 501 oats produces significantly more forage than Coker 227 in the fall but the reverse is true for spring forage production. Oats can be planted about one month earlier in the fall than rye or wheat because oats have more resistance to seedling diseases, and are more tolerant of heat stress.
Rye is well suited to many multiple-cropping systems involving corn, peanuts, and vegetables and especially those that require the small grain be removed early as forage. Rye is better adapted than the other small grains to infertile, sandy, acid soils and will produce a good crop with less fertilizer. Rye grows at lower winter temperatures than the other small grains. It makes an excellent mulch for no-till corn and is easily killed by herbicides. The breeding program on rye is centered on leaf rust resistance and forage
production. Attempts to select types that have resistance to seedling disease are being made. Hopefully these types can be planted earlier in the fall. Tetraploid ryes that should do the same for rye production as tetraploid ryegrass has the ryegrass production are being developed. The tetraploids have larger seed and normally grow more vigorously than the diploid cultivars. The tetraploids develop early and remain vegetative longer in the spring than the diploid, and therefore, increase the length of the forage production season.
A screening program for rye is in progress to develop types that can be planted earlier for forage production. This has been done by planting the rye one month before the earliest recommended date, mowing the plots regularly during the winter, and then bulk harvesting the surviving plants. A number of single plant selections were made in 1979 after 5 cycles had been made. These will be increased and tested to determine if progress has been made in the development rye that can be planted earlier.
Triticale, a synthetic crop derived from wheat x rye hybrids shows promise for forage and feed grain production. Most of the research done with this crop has been done during the last ten years. In clipping trials, triticale produced less forage than rye but more than wheat in Florida (1). It is equal to rye and wheat as a spring silage crop but is inferior to oats (2), and is equal to or better than rye and wheat as a grazing crop (6). In Georgia, triticale has been found lacking in winter-hardiness and forage production (7). Progress has been made in improving grain quality and in developing shorter, earlier maturing, higher yielding types. New cultivars recently tested in Georgia (12), Alabama (14), and Florida (5) had higher grain yields than, the best cultivars of the other small grains. The first cultivar developed in the southeast was released during 1979 by Alabama A & M University (15). A number of cultivars have been released in Texas. Only a limited amount of triticale has been grown in the southeast.
Triticale produces vigorous, robust plants that are impressive in appearance and yield better than the other small grains under stress conditions of limited




12
moisture or high temperatures. It has large seed which are less dense than wheat. Slightly higher seeding rates may be required for triticale. Triticale seems to have fewer disease problems than wheat and is somewhat difficult to thresh. It appears to have some potential in minimum tillage, low energy applications but has a marketing problem since there are no regular marketing channels for triticale. Initial use will probably be restricted to the farms where it is produced.




13
REFERENCES CITED
1. Barnett, R. D., R. L. Stanley, Jr., W. H. Chapman, and R. L. Smith.
1971. Triticale: New feed grain and forage crop for Florida? Sunshine
State Agric. Res. Report. July-September. pp. 12-14.
2. Barnett, R. D., and R. L. Stanley, Jr. 1976. Yield, protein content, and digestibility of several species and cultivars of small grains harvested for
hay or silage. Soil Crop Sci. Soc. Fla. Proc. 35: 87-89.
3. Barnett, R. D., and H. H. Luke. 1976. The effects of fungicides on disease development, seed contamination, and grain yield of wheat. Plant
Dis. Reptr. 60: 117-119.
4. Barnett, R. D., and G. E. Sanden. 1978. Evaluation of various foliar fungicides for the control of leaf rust on wheat, 1977. Fungicides and
Nematicide Tests 33: 113-114.
5. Barnett, R. D., and H. H. Luke. 1979. Grain yield and agronomic characteristics of triticale in comparison with other small grains in Florida.
Soil Crop Sci. Soc. Fla. Proc. 38: 48-51.
6. Bertrand, J. E., and L. S. Dunavin. 1974. Triticale, alone and in a mixture, for grazing by growing beef calves. Soil Crop Sci. Soc. Fla.
Proc. 33: 48-50.
7. Brown, A. R., and A. Almodares. 1976. Quantity and quality of triticale forage compared to other small grains. Agron. J. 68: 264-266.
8. Kucharek, T. A. 1977. Profitable control of foliar diseases of wheat by aerial application of zinc ion-maneb complex fungicide. Plant Dis. Reptr.
61: 71-75.
9. Luke, H. H., R. D. Barnett, and S. A. Morey. 1977. Effects of foliar fungicides on the mycoflora of wheat seed using a new technique to assess
seed infestations. Plant Dis. Reptr. 61: 773-776.
10. Machacek, J. E. 1945. The prevalence of Septoria on cereal seed in
Canada. Phytopathology 35: 51-53.
11. Morey, D. D. 1973. Rye improvement and production in Georgia. Georgia
Agri. Exp. Sta. Res. Bull. 129.
12. Morey, D. D. 1979. Performance of triticale in comparison with wheat,
oats, barley, and rye. Agron. J. 70: 98-100.
13. Nelson, L. R., M. R. Holmes, and B. M. Cunfer. 1976. Multiple regression accounting for wheat yield reduction by Septoria nodorum and other
pathogens. Phytopathology 66: 1375-1379.
14. Sapra, V. T., and U. R. Bishnoi. 1979. Triticale improvement and production in Alabama. Alabama A & M University, Research Bulletin No. 1.
15. Sapra, V. T., J. L. Highes, G. C. Sharma, and U. R. Bishnoi. 1979.
Registration of Councill triticale. Crop Science 19:930.




CONSERVATION OF ENERGY IN NO-TILLAGE SYSTEMS BY MANAGEMENT OF NITROGEN
R. L. BLEVINS, W. W. FRYE AND M. J. BITZER
Energy conservation is a major concern and priority in agriculture today. The inputs of fertilizers, pesticides, and fuels in crop production have increased rapidly in recent years and farming is now a very energy dependent industry. About 80 percent of the energy used by agriculture is from liquid petroleum fuels and natural gas, which makes efficient use ofI energy in agricultural production even more important. No-tillage systems of crop production are one alternative for conserving energy. Conventional tillage of corn and soybeans requires large amounts of fuel in plowing and disking operations. Part of the fuel saved in no-tillageI due to fewer trips across the field is offset by slightly higher amounts of herbicides and, in some cases, higher rates of N fertilizer used for no-tillage corn production.I
The greatest single energy input into corn production is nitrogen fertilizer, representing almost one-half of the total energy input for no-I tillage corn. Conclusions from earlier work in Kentucky (Thomas et al., 1973; Blevins et al., 1977; M. S. Smith, Univ. of Ky., personal communication) which are pertinent to the N status under no-tillage compared to
conventional tillage include the following associated with no-tillage:
---Higher soil water content at the beginning of any particular rainfall eventI
--- Greater preservation of large soil pores by lack of tillage
--- Slower rate of organic matter decomposition
--- Less mineralization of N
---Higher immobilization of N.
These factors resulted in lower plant available N under no-tillage during the growing season due to higher leaching loss of NO 3, slower N releaseU from organic matter and greater immobilization These results led to recommendation of higher rates of N fertilizer for no-tillage corn production than for conventional tillage. But, more recent comparisons ofI yields of no-tillage and conventional tillage corn (Frye et al., 1978) showed a greater response to N fertilizer, higher yields at higher N rates, more efficient use of N fertilizer, and a lower input:output ratioI of energy with no-tillage.
R. L. Blevins and W. W. Frye are Associate Professors of Agronomy
and M. J. Bitzer is Associate Extension Professor of Agronomy, Department of Agronomy, University of Kentucky, Lexington, Kentucky 40546.
The investigation reported in this paper (No. 80-3-86) is in connection with a project of the Kentucky Agricultural Experiment Station and is published with approval of the Director.
14




I 15
H In this paper, we discuss the response of no-tillage corn to N fertilizer, compare the N efficiency in no-tillage and conventional tillage
systems, and suggest better ways to manage nitrogen in no-tillage corn production. By improved management of nitrogen, energy is conserved or
used more efficiently.
* Response to Nitrogen Fertilizer
A summary of corn yields from a long-term no-tillage and conventional
tillage experiment is presented in Table 1. On plots where no nitrogen was applied the 10-year average corn yield was 76 bu/acre for no-tillage
and 95 bu/acre for the conventional tillage treatments. We conclude that
combination of greater leaching losses, a slower rate of mineralization
and more immobilization of N resulted in lower yields and plants showing
more severe N stress during the growing season in no-tillage. Nitrogen
rates above 75 lb/acre resulted in slightly higher grain yield for notillage compared with conventional tillage. The lower yields with notillage at low levels of N fertilizer and higher yields at higher rates
of N fertilizer are similar to results reported by Bandel et al., 1975 in
Maryland and Moschler et al., 1974 in Virginia.
In our experiments (Table 1), highest yields were obtained during the
second and third years (1971 and 1972). Both of these years had a very I favorable distribution of rainfall for corn, whereas the first year
(1970) had low rainfall during the growing season. The high yield with
no nitrogen fertilizer is evidence that the soil initially had a high
potential for soil nitrogen mineralization. Yields produced in the tenth
year (1979) were comparable to the 10-year average, except for the
observed yield decrease in the zero nitrogen treatment of conventional tillage. This suggests that corn yields can be maintained over a long
period of time in no-tillage as well as conventional tillage.
I A comparison of yields on the Maury soil to yields on other well-drained
soils in Kentucky is shown in Table 2. Yields from no-tillage and
conve tional tillage receiving 150 lb N/acre showed the highest yield
increase for no-tillage on the Crider silt loam soil. The Crider is a deep, well-drained soil developed in residuum of limestone with a thin
layer of loess at the surface. The well-drained to moderately welldrained sloping soils with moderate porosity seem best suited for notillage systems in Kentucky. No-tillage on soils with high water table
or slow internal drainage often results in lower yields of corn than
conventional tillage. This is related to increased wetness due to the
surface mulch and cooler temperatures at planting time, which contribute I to lower plant stands, the development of stress conditions during early
stages of growth and, perhaps, denitrification loss of N.




16
Table 1. Summary of corn yields from limed plots on a Maury silt loam
soil at Lexington, Ky. with different levels of nitrogen and
no-tillage and conventional tillage systems. (Yields from
unlimed plots omitted for brevity.)
Tillage Nitrogen applied as NH4NO3 (lb/acre)
Year system 0 75 150 300
------ bu/acre ------------1970 NTt 90 99 99 105
CTt 91 90 90 90
1971 NT 99 166 170 173
CT 151 180 159 162
1972 NT 118 153 149 155
CT 130 161 159 165
1973 NT 66 119 126 121
CT 66 123 129 135
1974 NT 89 154 165 167
CT 129 162 163 162
1975 NT 60 97 100 106
CT 78 80 82 96
1976 NT 69 144 156 170
CT 85 129 141 141
1977 NT 58 106 109 115
CT 88 123 127 132
1978 NT 33 78 85 99
CT 67 100 97 100
1979 NT 73 118 123 121
CT 68 130 124 123
10-year NT 76 123 128 133
Ave. CT 95 128 125 131
tNT = No-Tillage; CT = Conventional Tillage.
Table 2. Average corn grain yields produced on well-drained soils in
Kentucky by no-tillage and conventional tillage systems with
150 lb/acre N.
Grain yields
Number of Conventional
year tested No-tillage tillage
-----------bu/acre---------Maury silt loam 10 128 125
Crider silt loam 5 158 133
Allegheny loam 3 175 174




17
Nitrogen Efficiency
Table 3 shows the N fertilizer efficiencyI/ values for the yield responses to each 75-lb increment of the 75- and 150-lb rates of N fertilizer for no-tillage and conventional tillage corn on the Maury soil at Lexington which was shown in Table 1. Grain yields from each pound of N fertilizer of both increments were greater for no-tillage than conventional tillage. This may be somewhat misleading with regard to the first increment, since the average yields with both the 0 and 75 lb/acre N treatments were lower for no-tillage plots than for conventional tillage (Table 1). But the efficiency values in Table 3 are based on increases in yield resulting from the added nitrogen fertilizer. If one looks at the yield response in Table 1 together with the N fertilizer efficiency values in Table 3, the results suggest the need for slightly more N fertilizer to obtain maximum yields in no-tillage; however, the nitrogen fertilizer is used more efficiently. The more efficient use of nitrogen in no-tillage corn is probably due to the soil moisture conserved by notillage.
Table 3. Efficiency of nitrogen fertilizer in no-tillage and conventional tillage corn grown on Maury soil at Lexington, Ky.
(Based on 10-year average yields.)
N fertilizer lb grain/lb Nt BTU in grain/BTU in N
applied No-till Conventional No-till Conventional
1st 75 lb/acre 35.1 24.6 9.5:1 6.7:1
2nd 75 lb/acre 3.7 -3.7 1.0:1 -1.0:1
tCalculated by subtracting yield without N fertilizer from yield with N fertilizer and dividing by incremental amount of N fertilizer applied, in this case, 75.
6,800 BTU/lb corn grain; 25,000 BTU/lb N.
Using a value of 25,000 BTU/lb of N, each lb is equivalent to less than one quart of gasoline (145,000 BTU/gal) or about one pint of diesel fuel (207,000 BTU/gal). Therefore, to realize the full effects of no-tillage on energy conservation, it must be viewed in terms of improved energy input:output ratio associated with higher crop yield or greater N efficiency. Table 3 shows the N fertilizer efficiency values converted to energy input:output ratios. They do not represent direct energy savings but represent more efficient use of energy in no-tillage crop production. No-tillage itself results in direct energy conservation through less fuel consumption than conventional tillage. These data point out that the energy saved with reducing tillage operations is not lost in additional N fertilizer that may be recommended for no-tillage corn.
1/ N fertilizer efficiency as used in this paper is grain yield with N
fertilizer minus grain yield without N fertilizer.




18
Effect of N Fertilizer Management Practices
Certain N fertilizer management practices may result in direct energy savings or more efficient use of energy in no-tillage systems. TheseI
practices may provide the N efficiency necessary to allow the farmer to use no-tillage and obtain the energy conservation benefits associated with it without requiring more N fertilizer to maintain yields equal toI or greater than conventional tillage.
As pointed out previously, loss of NO by leaching during the growing season was greater under no-tillage than under conventional tillage (Thomas et al., 1973). N may be lost also by denitrification when soil moisture remains above field capacity for periods of several days where easily oxidized organic matter is present. These conditions often occurI under no-tillage on soils with sticky clay subsoils or on soils with fragipans that retard internal water movement. To avoid these losses, a split application or delayed application of N fertilizer 4 to 6 weeksI after planting has become an accepted and useful management practice in Kentucky. Table 4 shows the results from a study of the optimum application of N fertilizer for corn on a well-to moderately well-drained, slowly permeable Hampshire silt loam soil. The delayed application of 150 lb/acre N as ammonium nitrate gave significantly higher yields. Yields, N fertilizer efficiency, and energy efficiency are favored by
delaying the N fertilizer on soils with slow permeability.
Table 4. Effect of time of nitrogen application as ammonium nitrate on
no-tillage corn production on a Hampshire silt loam soil in
Franklin County, Ky.3
Efficiency of N fertilizer
Yield lb grain/ t BTU in graPn/
N applied (lb/acre) (bu/acre) lb N added BTU in NI
0 '75 150 at planting 104 10.4 2.8:1
150 delayed 5 weeks 131 20.5 5.6:1I
75 at planting + 75 delayed 135 22.0 6.0:1
tCalculated by subtracting yield without N fertilizer from yield with N3 fertilizer and dividing by the amount of N fertilizer applied (150).
680BTU/lb corn grain; 25,000 BTU/lb N.3
Losses of N by leaching and denitrification are likely to be greater early in the cropping season in Kentucky, accounting for the beneficial effects of delaying application of N fertilizer. Fertilizer recommendations in Kentucky state that rates of N fertilizer can be decreased by 35 lb/acre N, if as much as two-thirds of the N is delayed 4 to 6 weeks for no-tillage corn on moderately well-drained soils and for conventionalI tillage corn on moderately well and poorly drained soils. The N saved by this practice represents about 875,000 BTU of energy or about 6 gal of gasoline per acre. It should be pointed out, however, that the NI




19
recommendation on soils with impaired drainage is 50 lb/acre more than on well-drained soils if the N fertilizer is all applied at planting. Thus, even with delayed application, at least 15 lb/acre more N is recommended for soils with impaired drainage as a safe-guard against the greater 'potential N loss.
An additional management practice recommended for no-tillage corn production on wet soils is delaying planting for 2 to 3 weeks later than the recommended planting date for conventional tillage corn. This practice usuallyresults in a better stand of plants and allows application of N fertilizer after the soil has dried out but before N demand is high in
the crop.
A nitrification inhibitor, nitrapyrin,./ sprayed onto granules of ammonium nitrate fertilizer which was broadcast on the soil surface substantially increased yields of no-tillage corn in experiments over several years at several locations in Kentucky (manuscript in review). Yield increases ranged up to 46%, depending on soil and weather conditions. The increased N fertilizer efficiency achieved by inhibiting nitrification also would represent considerable energy efficiency.
Another approach to energy conservation through N fertilization is to provide N to the no-tillage corn crop by growing winter-annual legumes as cover crops. Winter cover crops included in this research in Kentucky are h airy vetch, bigflower vetch, crimson clover and rye. Preliminary results show that the legumes can provide substantial amounts of nitrogen for no-tillage corn, with hairy vetch being more effective than the others. In 1979, grain yields on plots with hairy vetch but with no N fertilizer were statistically equal to yields on other plots with 88 lb/acre N fertilizer added. N fertilizer conservation of such a magnitude would represent considerable conservation of energy.
:Summary
No-tillage production of corn requires considerably less tractor fuel than conventional tillage, but N management is more critical due to slower mineralization, higher immobilization and potentially greater losses by leaching and denitrification of NO3. More N fertilizer may be recommended for no-tillage corn, but the N is usually more efficient, producing more grain/lb of N than under conventional tillage. Several N management practices have been shown to improve N efficiency in notillage experiments in Kentucky, thus contributing to energy conservation. These practices include delaying N fertilizer application for 4 to
*6 weeks after planting corn, growing winter-annual legumes as cover crops for no-tillage corn, spraying a nitrification inhibitor (nitrapyrin) onto N fertilizer granules, and delaying planting on wet soil until it has dried out and the potential for denitrification has diminished.
/ 'Nitrapyrin, 2-chloro-6(trichloromethyl) pyridine, is manufactured by
Dow Chemical U.S.A., Midland, Mich.




20 I
I
These management practices along with the generally more efficient use of N fertilizer in no-tillage allow farmers to obtain the energy conservation associated with fuel savings in no-tillage due to fewer trips across i
the field without having this advantage negated by application of higher rates of N fertilizer. Through efficient N management no-tillage can be both a direct and indirect energy conserving practice, and yields equal to or greater than conventional tillage can be maintained.
References
Bandel, V. A., Stanislaw Dzienia, George Stanford, and J. 0. Legg. 1975.
N behavior under no-till vs. conventional corn culture. I. First
year results using unlabeled N fertilizer. Agron. J. 67:782-786.
Blevins, R. L., G. W. Thomas, and P. L. Cornelius. 1977. Influence of
no-tillage and nitrogen fertilization on certain soil properties
after five years of continuous corn. Agron. J. 69:383-386.
Frye, W. W., J. N. Walker, and G. A. Duncan. 1978. Comparison of energy
requirements for no-tillage of corn and soybeans. Agron. Abs. p.
16.
Moschler, W. W., D. F. Amos, R. W. Young, A. H. Kates, and D. C. Martens.
1974. Continuous no-till corn. In R. E. Phillips (ed.) Proceedings of no-tillage research conference. University of Kentucky,
Lexington, July 16, 1974.
Murdock, L. W. 1974. No-tillage on soils with restricted drainage. In
R. E. Phillips (ed.) Proceedings of no-tillage research conference.
University of Kentucky, Lexington, July 16, 1974. I
Thomas, G. W., R. L. Blevins, R. E. Phillips, and M. A. McMahon. 1973.
Effect of a killed sod mulch no nitrate movement and corn yield.
Agron. J. 65:736-739.
Triplett, G. W., Jr. 1975. Fertilizer use for no-tillage systems.
Proceeding of TVA fertilizer conference. Louisville, Kentucky, July
29-31, 1975.
I




DOUBLE CROPPING SOYBEANS SUCCEEDING SOYBEANS IN FLORIDA
K. J. BOOTE
INTRODUCTION
Growing two crops during the warm season is possible in much of Florida where- soil temperature is adequate and the frost-free period exceeds 240 days. Soybean (Glycine max L. Merr.), because of its photoperiodic sensitivity, is usually planted as the second crop, either after a cool season cereal or after a warm season crop such as vegetables, melons, or early maturing corn (Zea may L.) in Florida (Guilarte et al., 1975; Prine et al., 1978; Gallaher et al., 1979). However, experiments in Florida by Boote (1977, 1980) demonstrated that early maturing soybean cultivars can be planted in March for maturity in late June, with sufficient time to plant a second warm season crop, such as adapted late-maturing soybeans (Guilarte et al., 1975; Prine et al., 1978; Akhanda et al., 1976).
In order to produce two soybean crops per year, the first crop must be planted early to a cultivar from early maturity groups (less than group V) so the crop will progress rapidly into seed growth and mature by late June (Boote 1977, 1980). The optimum Maturity Group (MG) for the first crop was Group III, although Groups II and IV were acceptable. When planted in March, cultivars of MG V through VIII were induced to flower by the initially short days, but theaccelerating daylengths delayed subsequent reproductive development and delayed maturity until September-October (Boote, 1977, 1980). Thus planting a second soybean crop was not feasible after MG V, VI, VII, VIII and later cultivars. Long photoperiods after flowering have been shown to prolong post-flowering development and reduce partitioning of dry matter to seeds (Johnson et al., 1960; Lawn and Byth, 1973; Raper and Thomas, 1978; Thomas and Raper, 1976). Hartwig (1954) observed flowering at 49 and 41 days after emergence for MG VI and VII cultivars planted April 10 at Stoneville, MS (latitude 330 20' N), but reported that the plants aborted nearly all early flowers and matured in October.
In addition to cultivar selection, March-planted early maturing soybeans may encounter several other problems including the hazard of late frosts and cool soil temperature which causes slow emergence and reduced early growth (Hartwig, 1954). When planted in lower latitudes including Florida, early maturity groups flower early, are short, and set their pods lower (Whigham and Minor, 1978; Boote, 1977). Incomplete canopy cover can be overcome by planting in narrow rows, but low pod set remains a more challenging problem.
This paper addresses the feasibility of double cropping soybeans succeeding soybean. Specific objectives were to evaluate soybean cultivars in a range of Maturity Groups for yield, reproductive development, and suitability as the first crop in double cropping systems or as the second crop in double
K. J. Boote is Associate Professor of Agronomy, Department of Agronomy, 304 Newell Hall, University of Florida, Gainesville, FL 32611.
21




22
cropping systems in Florida, and to evaluate row spacing, planting methods, and other cultural practices needed to grow two soybean crops per year in Florida.
MATERIALS AND METHODS
First Crops: Soybeans were grown during the spring seasons (1976-1979) at the University of Florida Agronomy Farm, Gainesville, FL (Latitude 290 40' N). The soybean cultivars and planting dates are listed in the Tables. The soil type in the experimental areas was Kendrick sand, a loamy, siliceous, hyperthermic Arenic Paleudult in 1976, 1978, and 1979; and a Gainesville sand, a hyperthermic, coated Typic Quartzipsamment in 1979. Soil pH was at recommended levels or corrected by preplant dolomite addition. Fertilizer (40 kg N, 35 kg P, and 133 kg K) was incorporated before planting the first crop. The fields were plowed and disked prior to planting. Agricultural chemicals are given as active ingredients per hectare. Nematode control was furnished in 1976 and 1977 by injecting 26 kg/ha of 1,2-dibromo-3-chloropropane. In 1978, fenamiphos (ethyl-3-methyl-4-(methylthio)phenyl(l-methylethyl)phosphoramidate) was disked in at 7.5 kg/ha. No nematocide was used in 1979. Weeds were controlled with pre-emergence herbicides: in 1976, 2.2 kg/ha alachlor (2-chloro-2', 6'-diethyl-N-(methoxymethyl)acetanilide) and 2.5 kg/ha dinoseb (2-sec-butyl-4,6-dinitrophenol); in 1977, 1.3 kg/ha benefin (N-butyl-N-ethyl-a, a,a-trifluoro-2,6-dinitro-p-toluidine), 2.6 kg/ha vernolate (S-propyl dipropyl thiocarbamate), 2.2 kg/ha alachlor, and 2.8 kg/ha dinoseb; in 1978, 1.3 kg/ha benefin; in 1979, 1.3 kg/ha benefin, 2.2 kg/ha alachlor, 2.2 kg/ha naptalam (N-l-naphthylphthalamic acid), and 1.1 kg/ha dinoseb. Moderate herbicide injury, probably from vernolate, was observed in 1977. Foliar feeding insects were not a problem; however, 0.5 kg/ha of methomyl (S-methyl-N-((methylcarbamoyl)oxy)thioacetimidate) was applied 25 May 1976 for an infestation of southern green stinkbug (Nezara viridula L.). Plots were irrigated to supplement rainfall during the season.
The experimental design was a randomized complete block. Replications numbered three, six, four, and four in 1976 through 1979, respectively. Seeds were planted in 31-cm rows in 1976 and 1977, 25-cm rows n 1978, and 35-cm rows in 1979. Seeding density ranged from 56 to 64 seeds/m. Each plot consisted of five or six rows 5 m long of which the center three or four rows were harvested for yield.
Reproductive development of cultivars was observed as days from emergence to R1 (50% of plants having one flower), R4 (50% having a 2.0 cm long pod anywhere on the plant), R5 (50% having detectable bean swelling in any pod), and R8 (95% of the pods at mature color). The reproductive stages differ slightly from those of Fehr et al (1971) and Fehr and Caviness (1977) in that R3, R4, and R5 stages pertain to pods at any node on the plant rather than at the top four nodes having fully-expanded leaves.
The soybeans were hand-harvested a few days after reaching R8 maturity, warm air-dried, and threshed. Yield of clean seed per plot was based on harvested areas (bordered middle rows) of 4.46 m2 in 1976 and 1977, 4.34 m2 in 1978,




23
and 5.12 m2 in 1979. Average height to tip of main stem was measured at maturity. Seed quality was rated on a scale of 1 (very good) to 5 (very poor). Weight per 100 seeds was determined. To estimate combine harvestability, at least 50 cm of bordered row was cut into two segments; soil line to 8 cm, and above 8 cm. Individual segments were threshed separately and percent seed weight below 8 cm height was determined. All data on reproductive development and yield characteristics were subjected to analysis of variance. Cultivar means were compared by the new Duncan's Multiple Range test. The error term was the cultivar by replication mean square.
Second Crop: The second crop 'Cobb' soybeans were planted 30 June 1977, 29 June 1978, and 27 June 1979 in 92, 46, and 35-cm rows respectively. Tillage prior to the second crop consisted of disking in 1977, plowing and disking in 1978, and no-tillage in 1979. No nematocide or additional fertilizer was applied. Alachlor, at 2.2 kg/ha was used all three years for weed control with addition of 2.2 kg/ha of glyphosate (N(phosphonemethyl)glycine) on no-tillage plots in 1979. Cultivation was done in 1977 and 1978. The second crops were irrigated in 1978 and 1979. Insecticides were needed in 1978 and 1979. Four yield replicates were harvested each year from bordered rows similar in area to the first crop. Yield and maturity characteristics were handled similarly to the first crop. To convert kg/ha to lb/ac, multiply by 0.892. Divide lb/ac by 60 to obtain bu/ac.
RESULTS AND DISCUSSION
Cultivars with Suitable Reproductive Development for First Crop: Maturity data from 1976 and 1979 (Table 1) shows cultivars from a range of Maturity Groups (MG). Maturity data from 1977 and 1978 were intermediate to those in 1976 and 1979. Reproductive development and maturity was prolonged in 1976, partially due to season and partially due to southern green stinkbug damage. In 1979, the only year nematocide was not applied, nematode injury may have hastened reproductive development and senescence, especially for the' first three cultivars listed.
Cultivars in MG 00 through I including 'Corsoy' (MG II) flowered early (29 days after emergence) and did not differ significantly in days from emergence to RI, R4, and R5. However, they differed up to 6 days in time to
maturity. Maturity Group II, III, and IV cultivars flowered 1 to 2 days later; thereafter, each respective MG was progressively somewhat slower in reaching each successive reproductive stage. The largest difference among MG 00 to IV cultivars occurred in days from R5 (bean swell) to R8 (95% pod maturity). The slightly slower reproductive development of MG II, III, and IV cultivars contributed to taller plants with 1 to 2 more nodes, but the significantly longer pod fill period (R5 to R8) gave these cultivars a considerable yield advantage over MG 00, 0, and I (Table 2).
The MG V, VI, and VII cultivars were delayed in flowering and slower in reproductive development than MG IV and earlier cultivars. They flowered at least 10 days later than MG IV cultivars. The substantial shift in reproductive behavior from MG IV to MG V is noteworthy. Reproductive




24
behavior of 'Essex', typical of MG V, was more comparable to that of MG VI and VII than to that of MG IV. 'Hill' does not exhibit flowering behavior typical of MG V (K. Hinson, Personal communication). Cultivars later than MG IV required 3 to 20 more days from R1 to R4 than did earlier MG's. Most of this delay was lag time before any active pod elongation. Subsequent reproductive development (R5 to R8) was also prolonged for MG V to VII cultivars. Essex and Hill set a reasonable pod load, but later cultivars such as 'Bragg' (MG VII) remained green and set pods at a very slow rate and did not mature until the normal time in October. Essex and Hill had 80 to 90% mature pods by 25 July and 31 July, respectively, but the remainder of the pods stayed green, and the plants retained one-third of their green leaf area at that time.
Table 1. Reproductive development of soybean cultivars planted in March
of 1976 and 1979 at Gainesville, FL.
Cultivar Maturity Nodes
Group at Reproductive Development Stage
Maturity RI R4 R5 R8
--------days after emergence-----------------March 1976t----------Fiskeby V 000 30ef* 38f 45f 77f
Altona 00 29f 38f 46ef 81e
Portage 00 29f 38f 46ef 82e
Clay 0 29f 38f 46ef 82e
Evans 0 30ef 38f 47ef 86d
Hodgson I 29f 38f 47def 87d
Steele I 30ef 39f 47def 85d
Corsoy II 29f 39f 47def 93c
Amsoy 71 II 31d 41e 48cde 94c
Williams III 32cd 42d 49cd 99b
Calland III 31de 42d 49c 109a
Cutler 71 IV 33c 44c 52b 109a
Bonus IV 33c 44c 50bc 108a
Hood VI 52a 71a 76a
Bragg VII 45b 68b 75a
- -------15 March 1979----------Maple Arrow 00 6.4e* 28e 37g 40f 76h
Amsoy 71 II 8.1d 29de 39fg 43e 79g
Woodworth III 8.6d 29de 39fg 44e 82f
Williams III 9.7c 30cd 40ef 43de 88e
Union IV 10.1bc 31cd 41cd 46c 90d
Franklin IV 9.8c 30cd 41de 44d 89de
Cutler 71 V 10.9a 32c 42c 46c 93c
Essex V 10.7ab 42b 56b 61b 124b
Hill V 11.3a 52a 64a 69a 131a
* Means in a column within a given year not followed by the same letter
are significantly different at the 0.05 level according to Duncans New Multiple Range test.
t Results for 1976 averaged over three planting dates: 8, 18, and 29 March, and three replications per planting date.




25
The cause for this abnormal reproductive behavior is the sensitivity of each particular genotype to photoperiod. The later the MG of a cultivar, the shorter days it requires to successfully complete reproductive development. When planted in March, the days were short enough to induce flowering and pod set of these later cultivars. But the subsequently lengthening days of May, June and July affected reproductive development even though flowering had been initiated. The later the MG, the more sensitive it is to the effect of a given lengthening photoperiod on reproductive development (Major et al., 19.75). This means that only certain combinations of cultivars and planting dates will fit for an early soybean crop at a given temperature-and-increasing-daylength location. For Gainesville, MG V and later cultivars planted in March were adversely affected by daylength and matured too late to allow a second crop. In fact, they produced less and poorer quality seed than if planted 't recommended dates (May-June). MG II, III, and IV cultivars were early enough to allow a second crop.
Yield Characteristics of First Crop Soybean Cultivars: Good yield levels were achieved in all four years under conditions of narrow rows, irrigation, and good weed control. A comparison of yield characteristics to maturity group indicates MG 000 to I cultivars were uniformily early, short and low yielding, with low pod set (Table 2). Their low yield potential can be attributed to a short filling period (days from R5 to R8). Successively later maturity groups were later maturing, taller, had poorer quality seed, and set fewer seeds below 8 cm. Potentially economical yield levels were generally achieved with MG III and IV cultivars which matured between June 20 and 30 at Gainesville if planted March 14. 'Amsoy 71' of MG II also
yielded well, except in 1979 when no nematocide was used. 'Williams' (MG III) was probably the most consistently good performer over the years. This agrees with Williams' unusually good adaptation in INTSOY's tropical-subtropical trials inspite of being in MG III (Whigham, 1975; Whigham and Minor, 1978). Certain other MG III and IV cultivars: 'Woodworth', 'Bonus', and 'Franklin' yielded significantly less than Williams. 'Union', being of Williams parentage, appeared similar to Williams. While 'Calland' (MG III) and 'Cutler 71' (MG IV) were tall and yielded well, they had some negative attributes: poorer seed quality, later maturity, and a tendency to maintain green stems and a few green leaves at maturity, possibly in response to lengthening days. This "staygreen" trait was even more pronounced on MG V cultivars which "matured" with poor quality seed in late July, but retained about one-third green leaves and about 10-20% green pods. While the plant and pod height of MG IV cultivars is desirable, their poorer seed quality and later maturity conflict with prompt early harvest in the warm humid rainy season in Florida which arrives in late June. Delayed maturity and harvest delays planting and reduces the growth period of the second soybean crop.
Second crop soybeans and total seed yield from two crops. Second crop 'Cobb' soybeans were planted June 30, June 29, and June 27 after harvesting early soybean crops in 1977, 1978, and 1979, respectively. First crop 'Williams' yield, second crop 'Cobb' yield, and combined yield of two crops is shown in Table 3. The yield potential of the second crop in 1977 was limited by incomplete canopy cover in 92 cm rows and growth under rainfed conditions. The




26
Table 2. Yield characteristics of soybean cultivars planted in March of
1976, 1977, 1978, and 1979 at Gainesville, FL.
Height Yield
Maturity Maturity at Seed below Seed
Cultivar Group Date t Harvest Yield 8 cm Qualitytt
cm kg/ha % 1-5
--------March 1976t- ----------I
Fiskeby V 000 6-5f* 33g 1890d 24a 1.6e
Altona 00 6-9e 53e 2600b 12def 1.8de
Portage 00 6-10e 51e 2610b 9efg 2.0cd 1
Clay 0 6-10e 45f 2150c 17abcd l.7de
Evans 0 6-14d 47f 2590b 12cdef l.8de
Hodgson I 6-15d 47f 2330c 14bcde 2.0cd
Steele I 6-13d 48f 2660b 17abcd 1.7de
Corsoy II 6-21c 52e 2910a 18ab 2.3bc
Amsoy 71 II 6-22c 59d 3110a Ildef 2.4bc
Williams III 6-27b 66c 3000a 10efg 2.4b I
Calland III 7-7a 75b 3010a 7fg 3.4a
Cutler 71 IV 7-7a 83a 2920a 5g 3.4a
Bonus IV 7-6a 78b 2650b 9efg 3.2a
------ -14 March 1977--------M65-217 00 6-8e 36d 2130bcd 22abc 1.3f
Altona 00 6-3f 39d 1940cd 20bc l.5def
Portage 00 6-4f 37d 1800d 12c 1.8bc
Maple Arrow 00 6-9d 40d 1990cd 21bc 1.4ef
Evans '0 6-9d 36d 2280bc 28ab l.8bcd
Corsoy II 6-14c 45c 2390b 31a 2.0ab
Amsoy 71 II 6-16b 55b 2990a 19bc 2.2a
Williams III 6-20a 60a 3200a 17c 1.7cde
------ -14 March 1978--------M65-217 00 6-12c 41c 1800b 27b 1.9b
Prize II 6-12c 36c 1540b 41a 2.4a
Amsoy 71 II 6-19b 52b 2630a 22bc 2.0b
Williams. III 6-22a 54b 2760a 12c 2.0b
Franklin IV 6-24a 60a 2320a 13c 2.2ab
-------- -15 March 1979-- ------Maple Arrow 00 6-7h 28h 1580d 12a 1.4f
Amsoy 71 II 6-10g 40g 1830d 10ab 1.7def
Woodworth III 6-13g 45f 1980cd 9abc 1.6ef
Williams III 6-19e 51e 2800b 4cd l.7def
Union IV 6-21d 55d 2900ab 6bcd 2.0de
Franklin IV 6-20de 60c 2370c Id 2.0d
Cutler 71 IV 6-24c 65b 2840ab ld 2.7c
Essex V 7-25b 55d 3280a # 3.2b
Hill V 8-la 72a 1880d # 4.3a
Means in a column within a given year not followed by the same letter are significantly different at the 0.05 level.
t Results for 1976 averaged over three planting dates: 8, 18, and 29 March.
Maturity dates for 1976 adjusted to a hypothetical 14 March planting date
to allow comparison to the other three years. tt1 = Very Good; 5 = Very Poor.
# Not measured, but was less than 3%. 1




27
yield potential of both the first and second crop in 1978 were limited by insufficient irrigation frequency in a dry season coupled with a sting nematode infestation in one-third of the experiment. In 1979 the two crops received nearly optimum irrigation and rainfall frequency, but received no nematocide. The excellent weather is reflected in the high yields for 1979. The 1979 yields were 2800 kg/ha (42 bu/ac) plus 3410 kg/ha (51 bu/ac) for a total of 62110 kg/ha (93 bu/ac) per season. Even under the adverse conditions of 1978, total yield was 4400 kg/ha (65 bu/ac), a yield more than twice the state average. The second crop responded well to narrow row spacing with a 30% increase in 1978 from 46 versus 92 cm rows and a 9% increase in 1979 from 35 versus 105 cm rows. The cultivar Bragg yielded as well as Cobb in the two years it was planted.
Table 3. Total yield of 'Cobb' soybeans succeeding 'Williams' soybeans
r during 1977, 1978, and 1979 at Gainesville, FL.
Row Planting Maturity Seed Total Year Crop Cultivar Spacing Date Date Yield Yield
cm kg/ha kg/ha
1977 First Williams 31 3/14 6/20 3200
Second Cobb 92 6/30 10/30 2070 5270
1978 First Williams 25 3/14 6/22 2760
3 Second Cobb 46 6/29 10/29 1640 4400
1979 First Williams 35 3/15 6/18 2800
Second Cobb 35 6/27 11/1 3410 6210
Tillage conditions differed for the second crops in each year. Disking in 1977 was not satisfactory, because it provided a good seed depth in which first crop soybeans volunteered in the second crop. This was not desirable, because volunteers from first crop seed were short, matured early, and had poor seed quality by the time the full season crop was mature. In other words, first crop volunteer soybeans acted like 'weeds'. Morever, the low pod set of the first crop is likely to result in sufficient cutter bar loss to give a volunteer soybean problem. After the 1978 early crop, the field was plowed with a moldboard plow to bury the seed lost during harvest. This worked, but the second crop was planted in dry soil and irrigated too heavily. Emergence andstand was reduced by soil compaction and weed pressure increased. In 1979, the second crop was seeded no-till into the residue left from the first soybean crop. Lasso-Roundup (2.2 kg/ha alachlor and 2.2 kg/ha glyphosate) were applied to control future weeds as well as weed escapes from the first crop. The second crop in 35 cm rows covered the ground quickly and weeds were not a problem. This no-tillage method effectively solved the volunteer soybean problem, controlled weeds, maintained soil moisture for germination, and speeded replanting with lower energy input.
Conclusions and Recommended Cultivars and Practices for Growing Soybeans Succeeding Soybeans in Florida: March-planting of soybean cultivars in MG 000 to VIII during four years indicated that the cultivar for the first crop




28
I
should be from MG II, II or IV for best yield potential, seed quality, sufficient pod and plant height, and sufficiently early maturity to allow a second crop. Williams was the best performing cultivar, but Union, Cutler 71, and I
Amsoy 71 were also good within MG II to IV. Cultivars from MG V, VI, VII, VIII, and IX, when planted in March, were adversely affected by the lengthening days. As a result their reproductive development was slow and they matured too late to allow planting a second crop.
Growing two soybean crops per year will require careful management. The first crop must be planted no later than the end of March on well-drained, productive 1 soils that have previously produced good soybean yields. Irrigation and good weed control are absolutely essential. Plant in narrow rows at populations near 60 plants per m2 (Table 4). This will give a closed canopy and reduce I
weed competition. Yield was increased 21% by planting in 25cm as compared to 102 cm row spacing. Yield was not increased by doubling seeding rate to 112 seeds/m2. The fraction of seed yield below 8 cm was reduced by either greater 3
in-row plant competition (fewer rows at the same area planting density) or by greater overall planting density at the same in-row competition. Because pods are set low, careful combine harvest and low cutter bar height are needed. Harvesting at the earliest possible time is essential to prevent loss of seed quality in the warm humid summer and to give maximum growing time for the
second crop planted. Spraying a harvest aid desicant such as paraquat (1,1'dimethyl-4,4'-bipyridiniumion)may be desirable if the last few leaves fail I
to die as pods begin to mature. Seed drying may be needed.
The second crop should be a full-season adapted cultivar. Bragg (MG VII) and Cobb (MG VIII) have performed better than the few MG IX experimental lines 3
tried. Best yield performance of the second crop occurred in years when notill planting methods, narrow rows, optimum irrigation was practiced. The 3
Table 4. Effect of row spacing and population on yield characteristics of
'Ansoy 71' and 'Williams' soybean planted 14 March 1978 at Gainesville, FL. I
Harvest Height Yield Weight
Row Plant at Seed below of 100 Seed
Cultivar Spacing Density Harvest Yield 8 cm Seed qualitytt
cm no/me cm kg/ha % g 1-5
Amsoy 71 25 47 52a* 2630a 22a 17.9abc 2.Oa
51 51 53a 2400a 15b 17.6bc 2.2a
51t 99t 53a 2370a 2c 16.9c 2.2a
76 50 55a 2130a llb 18.8ab 2.2a
102 50 59a 2280a 4c 19.4a 2.4a
Williams 25 47 54a 2760a 12a 19.8a 2.0a
51 50 55a 2610ab 6b 19.6a 1.9a
51t 98t 53a 2520ab lc 18.9a 1.9a
76 49 57a 2330ab 2c 20.1a 1.9a
102 48 58a 2190b 3c 19.9a 2.Oa
* Means in a column within a given cultivar not followed by the same letter
are significantly different at the 0.05 level according to Duncans New
Multiple Range test. 2
t This row spacing treatment seeded at 112 seeds/m2", all other treatments
seeded at 56 seeds/n2. I
ttl = Very Good; 5 = Very Poor.
I




combined total yields of two soybean crops per season were 5270, 4400, and 6210 kg/ha in 1977, 1978, and 1979. In spite of the apparent success of these experiments, further experimental and farm level evaluation is needed before the practice is recommended to Florida producers. Careful management is the key.
LITERATURE CITED
Akhanda, A. M., G. M. Prine, and K. Hinson. 1976. Influence of genotype and
row width on late-planted soybeans in Florida. Proc. Soil & Crop Sci.
Soc. of Florida 35:21-25.
Boote, K. J. 1977. Production potential for early maturing soybean cultivars
planted in March in Florida. Proc. Soil & Crop Sci. Soc. of Florida 36:
152-157.
Boote, K. J. 1980. Response of soybean maturity groups to March planting in
Southern USA. (Submitted to Agronomy J.).
Fehr, W. R., C. E. Caviness, D. T. Burmood, and J. S. Pennington. 1971. Stage
of development descriptions for soybeans, Glycine max. (L.) Merrill. Crop
Sci. 11:929-931.
Fehr, W. R. and C. E. Caviness. 1977. Stages of soybean development. Iowa
State University Cooperative Extension Service Special Report 80.
Gallaher, R. N, M. D. Reed, R. B. Forbes, F. M. Rhoades, and W. T. Scudder.
1979. Corn-soybean succession double cropping. University of Florida,
IFAS, Agronomy Department, Agronomy Fact Sheet No. 93.
Guilarte, T. C., R. E. Perez-Levy, and G. M. Prine. 1975. Some double cropping possibilities under irrigation during the warm season in north and
west Florida. Proc. Soil & Crop Sci. Soc. of Florida 34:138-143.
Hartwig, E. E. 1954. Factors affecting time of planting soybeans in the
Southern States. U.S. Dept. of Agr. Circular No. 943.
Johnson, H. W., H. A. Borthwick, and R. C. Leffel. 1960. Effects of photoperiod and time of planting on rates of development of the soybean in
various stages of the life cycle. Bot. Gaz. 122:77-95.
Lawn, k. J., and D. E. Byth. 1973. Response of soybeans to planting date in
Southeastern Queensland. Influence of photoperiod and temperature on
phasic development patterns. Aust. J. Agr. Res. 24:67-80.
Major, D. J., D. R. Johnson, J. W. Tanner, and I. C. Anderson. 1975. Effects
1 of daylength and temperature on soybean development. Crop Sci. i5:174-179. Prine, G. M., K. J. Boote, W. R. Ocumpaugh, and A. M. Rezende. 1978. Forage
ahd grain crops planted as a second crop during the warm season in north
and west Florida. Proc. Soil & Crop Sci. Soc. of Florida 37:109-114.
Raper, C. D., Jr., and J. F. Thomas. 1978. Photoperiodic alteration of dry
matter partitioning and seed yield in soybeans. Crop Sci. 18:654-656. Thomas, J. F., and C. D. Raper, Jr. 1976. Photoperiodic control of seed
filling for soybeans. Crop Sci. 16:667-672.
Whiigham, D. K. 1975. International Soybean Variety Experiment. First report
of results. Univ. of Ill. INTSOY Series No. 8.
Whigham, D. K., and H. C. Minor. 1978. Agronomic characteristics and environmental stress. pp. 77-118. In Norman, A. C. (ed) Soybean Physiology,
Agronomy, and Utilization. Academic Press, New York, 1978.




WEED CONTROL PROGRAMS FOR NO-TILLAGE SOYBEANS
B. J. BRECKE
Interest among growers in raising two or more crops per year on the same land area (multicropping) is increasing. One of the most successful such production systems in the southeastern United States has been double cropping soybeans after small grain (2). This system is suited to a wide area of the southeast where fall seeded small grains are harvested early enough for soybeans to be planted.
No-tillage planting of the soybeans has contributed to the success of double cropping because it allows establishment of the soybean crop with the least delay. This often results in more favorable soil moisture at planting and allows more time for the soybean crop to mature. Another important advantage in this time of rapidly rising fuel costs is the lower per-acre energy requirement for no-till compared to conventional planting. No-till also requires less labor and decreases soil erosion (1).
Weed Control Programs
In no-till cropping, as with conventional tillage systems, weeds must be controlled to obtain maximum crop yields. When soybeans are planted into the residue of a previously well managed small grain crop, there are some advantages from a weed control standpoint. First, any weeds present are usually small and therefore can be controlled easily with a foliar applied herbicide. Second, the small grain residue will act as a mulch for the soybeans and aid in preventing weed emergence.
Regardless of mulch effectiveness, however, herbicides are essential for weed control in no-till soybeans since cultivation is not possible. A contact-active herbicide will be needed to control any vegetation present at the time of planting while herbicides with residual (preemergence) activity will be needed to prevent further weed infestation. A postemergence treatment may also be required to control escapes from the preemergence application.
Weed control programs for no-till soybeans have been studied at the Agricultural Research Center, Jay, Florida for the past 4 years. The results of these studies indicate that, as in conventional tillage systems, a complete herbicide program is required to control the more troublesome weeds (trade and common herbicide names are listed in Table 1). The results summarized in Table 2 show that neither preemergence treatments nor directed postemergence applications alone provide complete weed control in no-till soybeans. The directed treatments did provide somewhat better control than the preemergence treatments but control was still less than desired.
The results from a 1979 test (Table 3) again show that preemergence applications were not as effective as desired. However, when a program including both a preemergence and directed postemergence application was used excellent control of both grass and broadleaf weeds was obtained. Examples of such proB. J. Brecke is Assistant Professor of Agronomy (Weed Science), Agricultural Research Center, Route 3, Box 575, Jay, Florida 32565.
30




31
grams include Paraquat + Surflan + Lexone preemergence plus either Lexone + Butyrac, Lorox + Butyrac, or Paraquat directed postemergence. To obtain the best results the directed postemergence applications should be made to soybeans at least 12 inches tall and to weeds less than 3 inches tall. The spray should not contact more than the lower one-third of the soybean plant. The addition of a surfactant will improve control.
Conclusions
Though the mulch provided by residue from a small grain crop will aid in controlling weeds, herbicides are an essential part of a no-till cropping system. A good herbicide program includes a contact-active material to control any vegetation present at the time of planting in combination with herbicides which provide residual control of both grass and broadleaf weeds. A directed postemergence application may be required in instances where preemergence materials do not provide the desired weed control.
References
1. Gallaher, R. N. 1977. Soil moisture conservation and yield of crops
no-till planted in rye. Soil Sci. 41:145-147.
2. Lewis, W. M., and J. A. Phillips. 1976. Double cropping in the eastern
United States. p. 41-50.. In M. Stelly (ed.), Multiple cropping. Amer.
Soc. of Agron., Madison, WI.
Table 1. List of common and trade names
of herbicides described in this paper.
Common name Trade name
Paraquat Paraquat
Metribuzin Sencor or Lexone
Linuron Lorox
Oryzalin Surflan
2,4-DB Butyracor Butoxone




32
Table 2. Weed control in no-till soybeans at ARC, Jay, 1976.
Rate When
Treatment lbs/A applied % Control2
a.i. CB TM
Paraquat + Sencor .5 + .5 PRE + PRE 69 69
+ X77 + .25% + PRE
Paraquat + Lasso .5 + 2 PRE + PRE 54 70
+ Lorox + X77 + 1 + .25% + PRE
Paraquat + X77 + .5 + .25% + PRE + PRE 84 88
Sencor + 2,4-DB .38 + .25 + DP + DP
Paraquat + X77 + .5 + .25% + PRE + PRE 74 84
Lorox + Butyrac .5 + .25 + DP + DP
IPRE = Preemergence in the soybeans; DP = directed postemergence. 2CB = Cocklebur; TM = tall morningglory.
Table 3, Weed control programs for no-till soybeans at ARC, Jay, 1979.
Rate When
Treatment lbs/A' applied % Weed Control2
a.i. CG TM BW
Paraquat + Dual + .25 + 1.5 + PRE + PRE + 53 80 83
Lexone + X77 .5 + .25% PRE + PRE
Paraquat + Lasso + .25 + 2 + PRE + PRE + 83 80 73
Lexone + X77 .5 + .25% PRE + PRE
Paraquat + Surflan + .25 + 1 + PRE + PRE + 80 53 90
Lexone + X77 .5 + .25% PRE + PRE
Paraquat + Surflan + .25 + 1 + PRE + PRE + 91 100 100
Lexone + X77 + .5 + .25% + PRE + PRE +
Lexone + Butyrac + .5 + .25 + DP + DP +
X77 .25% DP
Paraquat + Surflan + .25 + i1 + PRE + PRE + 95 100 100
Lexone + X77 + .5 + .25% + PRE + PRE +
Paraquat + X77 .25 + .25% DP + DP
Paraquat + Surflan + .25 + 1 + PRE + PRE + 83 95 98
Lexone + X77 + .5 + .25% + PRE + PRE +
10orox + Butyrac + .5 + .25 + DP + DP +
X77 .25% DP
1PRE = Preemergence to the soybeans; DP = directed postemergence.
2CC = Crabgrass; TM = tall morningglory; BW = Florida beggarweed.




DEEPER ROOTING IN MINIMUM TILLAGE TO CONSERVE ENERGY
Robert B. Campbell
Conserving energy in the 1980's is more than just reducing fuel or "petrol" use. We would like to believe a little energy conservation is essential, preferably by someone else or by some governmental action that will provide us with labor saving productivity improvements to maintain the comforts we have become accustomed to. Scientific reality, however, dictates that quick easy solutions will not be developed without careful planning for the efficient use of our energy resources and without strong efforts to find and develop new sources of energy. Because. agriculture is the primary source of our food supply, energy must be considered in relation to the total crop production potential, i.e. production per petrol dollar spent or production per unit of energy input.
Reduced tillage defined
No-till farming in concept is directed to lower use of energy for crop production. Unfortunately the word no-till is misleading, in fact, no-till is. not no till at all. The term has been coined to refer to a system of residue management. In this system, seeds are drilled into sol, with live or dead plant materials still remaining on the soil surface. Weeds are mostly controlled by the application of constant or residual grass and broad leaf herbicides. However, mechanical weed control is possible under some circumstances. This concept of residue management has been referred to as eco-fallow (2), minimum till (5), or conservation tillage (3). These systems require higher levels of soil and crop management than conventional clean till farming methods.
Advantages and problems in minimum tillage
Often claimed-advantages of minimum tillage over conventional tillage include: lower erosion, water conservation, ability to plant
earlier, planting on steeper less fertile slopes, lower fuel costs, and lower compaction (5). Minimum tillage methods can be used in multiple cropping systems (4). Even though these appear to-be distinct advantages, there are disadvantages or special challenges that must be addressed to make minimum tillage successful. Because minimum tilled land is not smooth and open, stands of crops are difficult to establish. Birds, and rodents are more active because the residue provides protective cover. Fungi and insects infestations are more common when residues remain on the surface. The real question is how can these problems be solved. Most certainly they can be solved, but only with greater scientific input.
Robert B. Campbell is a Soil Scientist at the USDA-SEA-AR, Coastal Plains Conservation Research Center, Florence, South Carolina 29502.
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34
The soil physical system and minimum tillage
Recognizing soil physical and chemical conditions is an essential part of residue management in different parts of the country. MinimumI
till farming in the Southeast has to be accomplished in deep sandy soils or in sandy loam or loamy sand soils with genetically compact or mechanically compacted layers (1). These soils also have low water retentivity, consequently it is just as important to consider deep rooting and ways of achieving deeper rooting in minimum tillage as in conventional tillage. Without giving proper attention to these soil physical conditions, minimum tillage practices would eventually reduce the production base and actually increase energy use per unit of crop production.u
In view of the limitations that soil physical conditions may have on residue management and energy use, corn rooting patterns were studied in relation to soil strength and soil water availability to corn in a Norfolk loamy sand soil with a compact A2 hrzn ag cegso
these soils occur in the Southeast. For example, in Florence County, South Carolina alone, 58% of the tilled soils have an A layer (1). Although these layers vary in compactness, they are easily compacted byI tillage tools and wheel traffic.
Describing soil physical parametersI
Soils are never uniform in texture, structure and bulk density. Roots
are not symetrically distributed in soil, therefore, water withdrawal can not be uniform. Consequently, a mean value and frequency distribution of certain properties such as bulk density are frequently used to describe soil conditions shown in Table 1.
Table 1. Bulk density and related frequency distributionI
for a Norfolk soil at Florence, SC
Bulk Density Relative Frequency %I
g/cm 'A 2B
1.25-1.29 10.0
1.30-1.34 4.3 5.0I
1.35-1.39 2.1 5.0
1.40-1.44 2.1 5.0
1.45-1.49 8.7 20.0
1.50-1.54 26.1 30.0
1.55-1.59 17.5 20.0
1.60-1.64 8.7 2.9 5.0I
1.65-1.69 8.7 7.7
1.70-1.74 17.4 15.4
1.75-1.79 2.2 32.7
1.80-1.84 2.2 38.5
1.85-1.89 1.9
1.90-1.94 0.91
Mean g/cm3 1.57 1.78 1.48
Std. deviation 0.155 0.049 0.099
Schewness -0.0107 -0.2283 -0.7704I




35
The mean bulk density values for the Ap, A and B horizons are 1.57, 1.78, and 1.48 g/cm3, respectively. The wide distribution of the Ap layer is a result of subsoiling in a minimum tillage experiment in whic ,corn was planted into a standing rye cover crop. The subsoil tool- produced a narrow slot 10-15-cm wide in the A2 layer that penetrated 47 cm, about 5 cm into the B horizon. The Ap bulk density measurements were more normally distributed about the mean value than the A2 *or B horizons.
Rooting and soil strength
Increasing bulk density increases resistance to rooting but bulk density is not the only factor that affects rooting because decreasing soil water content also increases the strength of soil. Therefore, root penetration is a function of bulk density, water content, and texture. We have determined that soil probes give a reliable index of rootability in soil, and that a penetrometer index of 20 kg/cm2 represents a value beyond which few roots penetrate. In the Ap horizon at the mean bu k density of 1.57 root penetration is severely restricted at a iric potential of a little over -1000 mb. One could anticipate that roots would be well distributed throughout the A2 horizon because of the wide range in the bulk density frequency distribution (see Table 1). In the A horizon however, the metric potential at which roots were restricted was -220 mb at a mean bulk density of 1.78 g/cm3. Root development observations in a corn field showed that rooting in the A2 horizon occurred only in the subsoiled portion of the A2. Rooting in the B hori zon was restricted to those roots that extended down the A2 subs'oiled soil. The B horizon had the lowest bulk density of all layers studied, 1.48 g/cm3. Rooting observations demonstrated that once a root grew through the disturbed A2 horizon, root growth into the I B horizon was only slightly impeded. Because soil strength restricted rooting,. soil strength affects water availability. By taking -50 mb as the upper limit of water availability and the water content corresponding to 20 kg/cm2 as the lower limit of water availability to the plant, the amount of water storage for each layer to the 75-cm depth can be calculated. ese calculated water storage values are given in Table 2.
Table 2. Water storage in a 75-cm profile based on
-50 mb and the metric potential water content at 20 kg/cm2
as the upper and lower availability water limits, respectively.
(only the subsoiled protion of the A2 was considered)
Layer Depth Storage
(cm) (cm)
Ap 0-17 2.37
A2 17-35 0.30
B 35-75 2.91
Total 5.58
I/ Brown-Harden Superseeder with an attached subsoil tool. Mention of ,tradenames is for reference and does not constitute endorsement by USDA or its cooperators.




36
Various assumptions were made for calculating effective soil water storage. Four examples taking various limiting factors into consideration are presented in Table 3.
Table 3. Calculated available water storage in a Norfolk loamy
sand profile to depth of 75 cm.
Limiting Condition for Estimating Soil Water Storage
Available Water (cm)
(1) -50 mb and -1000 mb upper and
lower limits 7.1
(2) -50 mb to 20 kg/cm2 strength
(all layers) 6.0
(3) -50 mb to 20 kg/cm2 in (subsoiled
in A2 only) 5.6
(4) -50 mb and -1000 mb in actual
observed rooting volume 4.0
These data show the importance of having roots uniformly distributed throughout the soil profile and further the necessity of expanding the volume of rooting in the B horizon. If roots were restricted only to the A horizon, the effective water availability to the plants would have been about 43% of that of the subsoiled soil 2.37 vs. 5.58 cm.
These soil water storage calculations do not take into account the amount of water that would have been provided to the plant by unsaturated flow for most regions in the soil to the root surfaces.
These data indicate efficient energy use in minimum tillage agriculture when depth of rooting and methods of offsetting the effects of drought are taken into account. High crop production insures efficient use of fuel that has been expended in establishing the crop which is an important aspect of the energetics of residue management.
References
1. Campbell, R. B., D. C. Reicosky, and C. W. Doty. 1974. Physical
properties and tillage of Paleudults in the southeastern Coastal
Plains. J. Soil and Water Cons. 29:220-224.
2. Fenster, C. R., G. A. Wicks, and D. E. Smika. 1973. The role of
eco-fallow for reducing energy requirements for crop production.
Abstracts American Soc. of Agronomy 64:122.
3. Reicosky, D. C., D. K. Cassel, R. L. Blevins, W. R. Gill, and G. C.
Naderman. 1977. Conservation tillage in the Southeast. J. Soil
and Water Cons. 32:13-19.
4. Sanford, J. 0. 1974. Double crop for more grain. Mississippi Agric,
and Forestry Expt. Sta. Information Sheet #1255.
5. Wells, K. L. May-June 1979. Why No-till. Fertilizer Solutions.
48-62.




FUEL CONSUMhPTION AND POWER REQUIREMENTS I FOR TILLAGE OPERATIONS
Richard P. Cromwell, James M. Stanley, I Raymond N. Gallaher, David L. Wright
it is estimated that well over half of the engine horsepower used on
American farms is for tillage operations. Many of the implements
used, and much of the need for tillage operations have long been taken
for granted. Reducing tillage operations was of considerable interest before the advent of high priced energy, but interest increased
sharply when the price per gallon of fuel jumped to three digits.
Diesel tractors are more efficient than gasoline tractors (a diesel
uses about 70% as much fuel for a given job than a gasoline tractor).
Tractors used to perform tillage operations were some of the first to -use diesel engines because they were relatively high horsepower units
that offered the greatest opportunity to recapture the diesel's higher
initial cost. The transition to diesel is virtually complete today.
Diesel engines are found in the large multi-hundred horsepower land
I preparation tractors down to sub-20 horsepower imported tractors. Many
manufacturers of water cooled tractors either do not offer a gasoline engine powered unit or only prepare one on special order. Therefore, I fuel consumption figures reported in this paper are considering diesel
tractors exclusively.
Most of the published information used for determining farm implement I energy requirements were derived from data gathered in the Midwest.
This data would probably be appropriate for many farm implements, but
energy requirements for tillage implements could be appreciably different because of soil type.
I Determining Implement Energy Use
'Reasonably accurate energy use data can be determined by simply filling the tank to the top, using the machine over a measured area, and determining the fuel used by accurately measuring the fuel needed to restore
the level in the tank, if a relatively large area is being worked, the
tractor is on level ground, and the tractor is shook vigorously to expel
air bubbles from the tank.
Richard P. Cromwell, Associate Professor, Agricultural Engineering Department; James M. Stanley, Visiting Professor Agricultural Engineering Department; Raymond N. Gallaher, Agsociate Professor, Agronomy Department; David L. Wright, Assistant Professor, Agronomy Department. Institute of
Food and Agricultural Sciences, University of Florida, Gainesville,
3 Florida 32611.
U3




38 1
In order to increase the accuracy of energy use values when workingI smaller areas, and~to speed up the operation by eliminating the need for burping air bubbles from the tank, a plexiglass tube was mounted on the fuel tank of a tractor as shown in Figure 1 below. This arrangement makesI it possible to get a relatively large fuel level change in the tube when working smaller areas than would be feasible with the "Tank Refill" method.3
TUBE
FIGUREl 1
The first tube that was mounted on the tractor had a 2 inch inside diameter and would give a large, easily measured fuel level change when the tractor was used for a short time. However, a small change in the temperature of the tractor fuel caused a significant change in the fuel level in the tube. The tube was changed to a 4 inch inside diameter tube in order to reduce the error induced by fuel volume change.
Results of Implement Energy Requirement TrialsI
Corn was planted at three different locations in the Gainesville area beginning in February, 1980. The soil preparation and planting treatments were as shown below:
1) Disk, moldboard plow, disk, subsoil, plantI
2) Disk, moldboard plow, disk, plant
3) Subsoil, plant
4) plant
The energy requirements for these operations were determined using the
"Tank Refill" method. Even though the plot areas were only 0.3 acres toI
0.9 acres, which is probably small for determining fuel requirements by tank refilling, the results given in Table 1 fall in a rather narrow band. A great amount of credit for this uniformity of results is attributed to the amount of tractor shaking done to expel air bubbles.




39
Table 1 Corn Planting Energy Requirements
Location Energy Used Per Operation (Gallons/Acre)
Plot First Plowing Second Subsoil and Plant
Number Disking Disking Plant
1 0.54 1.63 0.75 1.53
2 0.64
3 0.41 1.40 0.65 0.83
Gainesville 4 1.39
5 0.53 1.43 0.61 0.77
6 0.53 1.50 0.50 1.31
7 1.23
8 0.64
1 0.56 1.27 0.63 1.19
2 0.74
3 0.51 1.47 0.53 0.86
Newberry 4 1.24
5 0.51 1.42 0.60 0.85
6 0.51 1.36 0.60 1.31
7 1.27
8 .... .,76
1 0.58 1.40 0.67 1.32
2 0.73
3 0.51 1.35 0.62 0.87
Chiefland 4 1.44
5 0.49 1.34 0.57 0.87
6 0.49 1.33 0.60 1.32
7 1.44
8 0.73




40
The equipment used to perform the soil preparation and planting operations were: an eight foot wide tandem disk, a 3 bottom plow that cut approximately a 4 foot-6 inch slice, a two row Brown-Harden no-till planter with subsoiling shanks, a two row Brown-Harden no-till planter without subsoiling shanks, two sets of unit planters for mounting on the two no-till units, a 52 horsepower tractor, and a 58 horsepower tractor.
The data indicates that at all locations the initial disking required approximately 0.5 gallons per acre. The moldboard plowing required approximately 1.40 gallons per acre. The second disking required approximately 0.6 gallons per acre'of 0.1 gallons per acre more than the initial disking because of more slippage. The no-till planter equipped with the subsoiler shanks required about 1.30 gallons per acre. When the no-till planter did not have subsoiling shanks approximately 0.75 gallons per acre was used for planting. Subtracting the no subsoiling from the subsoiling figures indicates that approximately 0.55 gallons per acre were required for the subsoiling operation.
Tests were also conducted at the Agricultural Experiment Station in Quincy, Florida to determine the energy requirements for some tillage operations in heavier soil than those found in the Gainesville area. The results are shown in Table 2.
Table 2 Tillage Energy Requirements, Quincy
Operation Depth of Cut (inches) Gallons/Acre
Tandem disk 5 0.66
Offset disk 6-7 0.96
Rolling cultivator shallow 0.36
The tandem disking operation was performed by a 12 foot wide unit with 20 inch scalloped disks drawn by an 85 horsepower tractor. The offset disk was a 7 foot wide unit with 20 inch scalloped disks drawn by a 52 horsepower tractor. The rolling cultivator was a 4 row unit drawn by a 150 horsepower tractor.
Comparison with Other Published Data
The following is a comparison of the tillage energy requirements published by Iowa State University and those recently determined in Florida.




41
Field Operation Gallons/Acre
Iowa Florida
Moldboard plow 1.90 1.40
Offset disk 0.95 0.96
Tandem disk 0.45 0.50
Rolling cultivate 0.40 0.36
How Might Energy Requirements Be Reduced
'Farmers cannot use tractor engine efficiency as the sole guide for determing what tractor to buy because of practical considerations like dealer location and dealer's ability to provide parts and service. However, it is felt that more thought should be given to engine efficiency in order to reduce energy requirements. The results of the Nebraska Tractor Tests conducted over the last 10 years reveal that the 24 most efficient tractors delivered 13.91 horsepower hours per gallon while the 24 least efficient tractors delivered 11.16 horsepower hours per gallon. This is a difference of 24.6% and farmers must be made more aware of how to use Nebraska Test Data.




HERBICIDE TOLERANCE AND WILD RADISH CONTROL IN LUPINE AND VETCH
G.R. England, W.L. Currey, and R.N. Gallaher
INTRODUCTION
Wild radish (Raphanus raphanistrum Crantz) is a common weed in grain crops throughout the world. Wild radish is a self pollinated annual found mainly in cereals, fallows, and non-crop areas. In Florida it grows as a winter annual in these sites. It is a moderate to vigorous competitor for space.
Extensive work in the control of this weed has been done in Germany, the Soviet Union, and Great Britan. Research has been carried out world wide on the control of wild radish in numerous crops, using many herbicides. In Brazil, wild radish was controlled with 2, 4-D applied by air (Guibert, 1972). Merich et al. (1972) found BAS 3580H (bentazon 26% and dichloroprop 34%) and BAS 3960H (bentazon 25% and mecoprop 37.5%) controlled wild radish, Chrysanthamum segetum, Cusicim spp., Galum aparine, Matricaria p., and Sinapsis arvensis. Hahn (1973) controlled wild radish in grasses with SYS 67ME (MCPA 86% free acid) at 1.5 kg/ha and SYS 67 Prop (dichloroprop potassium 64% acid). Koboreva (1971) controlled wild radish in buckwheat (Fagopyrum tataricum) with 1-2 kg/ha 2, 4-D amine. Treating with MCPA (1-2 kg/ha) or norea (0.5 kg/ha) increased yields of buckwheat by 1000 kg/ha. Osususka et al. (1973) gained twice the control of wild radish compared to the check with 0.25 kg/ha of atrazine. Cochet et al. (1973) obtained control with Phyt 3425 (chlormtofen 20% + linuron 5%) at 1.85-5.0 kg/ha. Huggenburger et al. (1974) obtained control of wild radish, Digitaria singuevalis, Amaranthus 2., Polygonium spp., and Sinapsis arvensis with oryzalin
1.0-1.4 kg/ha + linuron (1.0-1.4 kg/ha) applied surface preemergence with 12.5 mm precipitation.sor shallow incorporation. Hermant et al. (1973) treated 4 cm flax (Linum usitatissimum) and R. (raphanistrum) in an early stage with bentazon and achieved good weed control with no injury to the flax. Detrernix et al. (1973) achieved control of Raphanus with alachlor (1.7-2.0 kg/ha) or propachlor (0.5 kg/ha) applied preemergence. Leiderman et al. (1972) controlled wild radish with oxadiazon (1.5-2.0 kg/ha). Amaranthus vidis, Galingosa parviflora, and Digitaria sanguinalis were also controlled.
Wild radish is a problem in winter forage crops at the Robinson Farm in Williston, Florida. Since this problem weed existed in land already utilized for research, the following experiment was established to determine possible control measures that could be utilized to control wild radish in lupine, Lupinus angustifolia, and vetch (Vicia villosa).
G.R. England, W.L. Currey, and R.N. Gallaher are Weed Science Graduate Student, and Associate Professors, Agronomy Department, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, Florida 32611.
42




43
MATERIALS AND METHODS
The experiment was conducted at the Robinson Farm in Williston, Florida during the winter of 1979-1980. Wild radish control was evaluated in lupine and vetch which were planted behind several no-tillage operations. The land was harrowed three times and then "Hairy vetch" (33.6 kg/ha) and "Frost lupine" (89.6 kg/ha) were properly inoculated and drilled on November 1, 1979. Lupine was irrigated (3.2 cm) on November 9, 1979 and vetch was irrigated on November 10. A portion of both lupine and vetch received an application of bentazon (1.12 kg/ha) on January 3, 1980. The bentazon was applied in a 280 1/ha spray at 2.8 kg/bm4.
On January 15, 1980, three chemicals, acifluorfen (Blazer), bentazon (Basagran), and 2, 4-DB (Butyrac) were applied postemergence to vetch and lupine.
Herbicides Rate
acifluorfen 0.28, 0.43, 0.56
bentazon 0.84, 1.12
2, 4-DB 0.28, 0.56
AG-98 at 0.25% v/v was added to acifluorfen. Two applications of each chemical were made to lupine and vetch which had been previously treated with 1.12 kg/ha bentazon and to plots not previously treated. The major weed to be studied was wild radish.
The herbicides were applied with a C02 backpack plot sprayer in 187 1/ha spray at 3.36 kg/cm2 on January 15, 1980. The second application of acifluorfen and bentazon was made on January 28, 1980 to wild radish plants that were 61 cm high. The second application of 2, 4-DB was made on February 3, 1980. The same method of application was used.
Each experiment was set up in a randomized complete black design and 4 replications were used. The treatments were rated by 4 visual observations for crop tolerance and wild radish control. A rating of 0 equals no affect on the crop or the weed, while a rating of 10 equals complete control of either the crop or the weed.
RESULTS AND DISCUSSION
In the four visual ratings there were significant differences between both weed control and crop tolerance (Tables 1. 2. 3, 4). By the fourth rating, acifluorfen and bentazon had provided almost complete wild radish control at all rates. Acifluorfen had caused from moderate to severe crop injury in vetch and severe crop injury in lupine. Bentazon caused no crop injury in vetch but almost completely removed the lupine.
Bentazon provided good wild radish control in both crops. There was excellent crop tolerance in vetch, but no crop tolerance of bentazon in lupine. Acifluorfen provided comparable weed control to bentazon. There was some tolerance orf vetch at the low rate.




44
2, 4-DB, due to the advanced stage of growth of WR at application, provided no wild radish control. It caused slight crop injury in both vetch and lupine. In vetch it caused leaf curl and in lupine it caused the stem to curl.
The timing of application was not optimum for control with selective herbicides. It is significant that good control of the weed by bentazon and acifluorfen was obtained in this stage of growth.
There seemed to be an interaction with bentazon and temperature. Control of wild radish appeared to be enhanced by hard freezes after application. This was observed at Williston and in wild radish treated with 0.84 kg/ha basagran at the Green Acres research farm.
Bentazon has been shown to be affected by environmental factors (BASF Tech. Info., Bull. No 7804). An optimum temperature for bentazon would be over 18 C (Ellison, 1980). This temperature relationship would have to be considered when determining a control program for a winter weed, since winter temperatures in Florida vary so much.
This experiment should be repeated to observe the activity of these chemicals on the crop and weed, in an earlier growth stage. The affects of temperature on bentazon need to be evaluated further.
REFERENCES
1. Cochet, J.C., Pavot, J., Butler, A., Devidal, R., Bouchan, F. 1973.
A study of recent pre and post emergence herbicides in soft winter
wheat. Weed Abstracts 1975.
2. Detrernix, L., Kaqrenne, W. 1973. Consideration on 3 years herbicide trials in winter rape crops. Weed Abstracts 1975.
3. Ellison, E. 1980. Personal communication.
4. Guibert. 1972. Agricultural Aviation in Brazil. Agric. Aviat. 14(3) 76-81.
5. Hahn, E. 1973. Experience in the use of herbicides on newly sewn grasslands. Weed Abstracts 1973.
6. Hermant, P., Beardin, X., Noivel, M., Serna, G., Lutanid, G., Lipatoff, V. 1973. Bentazone for the control of broadleaf weeds in flax. Weed
Abstracts 1975.
7. Huggenburger, F., Saipe, N., Lesniuc, O. 1974. Oryzalin plus linuron, a new herbicide combination for pre emergence weed control in soybeans.
Weed Abstracts 1974.
8. Koloreva, A.A. 1971. The use of herbicides for weeding buckwheat.
Weed Abstracts 1974.
9. Merick, B.H.,Behrendt, S. 1972. Trials in cereals with bentazon (3isopropyl l-lh-2, 1, 3-benzothiadiazin) in combination with hormones
(BAS 3580H and BAS 3960H). In Proc 14th British Weed Control Conference.
British Crop Protection Conference. 666-672.
10. Leiderman, L., Grassi, N. 1972. A trial with 3 new pre emergence herhicides in carrots (Dawius carota). Weed Abstracts 1976.
11. Osuskaya, T.V. 1973. Herbicide phytotoxicity and activity in relationShip to nutrient level of plants. Weed Abstracts 1974.
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45
TABLE 1. Control of Wild Radish and Vetch Tolerance From the Use
of Herbicides Following an Application of 1.12 kg/ha
Bentazon.
Date
Treatment 1-26-80 2-3-80 2-7-80 2-14-80
Wild Radish Control
acifluorfen 6.0 a 8.5 a 9.9 a 9.9 a
bentazon 4.5 a 8.0 a 9.5 b 9.7 a
2,4-DB 1.0 b 1.0 b 1.0 c 1.0 b
check 1.0 b 0.0 b 1.0 c 1.0 b
Crop Tolerance
acifluorfen 2.5 a 5.5 a 6.5 a 6.5 a
bentazon 0.0 a 0.5 c 2.0 b 0.0 c
2,4-DB 0.0 a 2.0 b 0.0 b 3.0 b
check 0.0 a 0.5 c 0.0 b 0.0 c
A rating of 0 equals no affect on the crop or weed, while a rating of 10 equals complete control of either the crop or the weed.
Values among treatments within each date followed by the same letter are not significantly different at the 0.05 level of probability according to Duncan's new multiple range test.




46
TABLE 2. Control of Wild Radish and Vetch Tolerance From the Use of
Herbicides With No Previous Herbicide Application.
Date
Treatment 1-26-80 2-3-80 2-7-80 2-14-80
Wild Radish Control
acifluorfen 3.5 a 4.5 b 6.5 a 7.0 b
bentazon 1.5 b 6.0 a 8.5 a 8.25 a
2,4-DB 0.0 b 0.0 c 0.5 b 0.0 c
check 0.0 b 0.0 c 0.0 b 0.0 c
Crop Tolerance
acifluorfen 3.0 a 4.0 a 5.5 a 4.5 a
bentazon 0.0 b 0.5 b 0.0 b 0.0 c
2,4-DB 0.0 b 2.5 ab 2.0 b 2.0 b
check 0.0 b 0.0 b 0.0 b 0.0 c
A rating of 0 equals no affect on the crop or weed, while a rating of 10 equals complete control of either the crop or the weed.
Values among treatments within each date followed by the same letter are not significantly different at the 0.05 level of probability according to Duncan's new multiple range test.




47
TABLE 3. Control of Wild Radish and Lupine Tolerance from the Use of
Herbicides-Following an Application of 1.12 kg/ha Bentazon.
Date
Treatment 1-26-80 2-3-80 2-7-80 2-14-80
Wild Radish Control
acifluorfen 4.0 a 7.5 a 9.25 a 9.7 a
bentazon 2.0 b 8.0 a 9.25 a 9.5 a
2,4-DB 1.0 bc 1.0 b 1.0 b 1.5 b
check 0.5 c 1.0 b 1.0 b 1.0 b
Crop Tolerance
acifluorfen 8.0 a 9.45 a 9.9 a 9.9 a
hentaon 10.0 a 9.95 a 9.9 a 9.9 a
2,4-DB 2.0 b 5.0 b 4.0 b 2.5 b
check 0.0 b 0.5 c 2.0 b 2.0 b
A rating of 0 equals no affect on the crop or weed, while a rating of 10 equals complete control of either the crop or the weed.
Values among treatments within each date followed by the same letter are not significantly different at the 0.05 level of probability according to Duncan's new multiple range test.




48
TABLE 4. Control of Wild Radish and Lupine Tolerance From the Use
of Herbicides Following No Previous Herbicide Application.
Date
Treatment 1-26-80 2-3-80 2-7-80 2-14-80
Wild Radish Control
acifluorfen 3.0 a 4.5 a 6.5 b 8.25 a
bentazon 1.0 b 6.0 a 8.0 a 8.75 a
2,4-DB 0.56 b 0.0 b 0.0 c 0.0 b
check 0.0 b 0.0 b 0.0 c 0.0 b
Crop Tolerance
ac i fl uorfen
bentazon gb a
2,4-DB 5:g.b
check 0.5 b 0.5 b 0.0 d 0.0 b
A rating of 0 equals no affect on the crop or weed, while a rating of 10 equals complete control of either the crop or the weed. Values among treatments within each date followed by the same letter are not significantly different at the 0.05 level of probability according to Duncan's new multiple range test.




WEED CONTROL FOR NO-TILLAGE SOYBEANS IN RYE STRAW
RAYMOND N. GALLAHER AND WAYNE L. CURREY
INTRODUCTION
Soybean (Glycine Max L. Merr.) is an important cash crop to Florida agriculture. In recent years acreage has steadily increased and is expected to be over 500,000 acres by 1985. This crop has a potential gross value of over 100 million dollars annually, adding significantly to Florida's economy. Most of Florida's soybean crop is planted succeeding other crops such as small grains, vegetables, and corn in multiple cropping systems.
Significant acreage of small grains grown for grain is produced in Florida. Soybeans is an ideal crop to succeed small grain in a succession double croppihg system. Past experience shows that no-tillage planting of soybeans into small grain straw can have advantages as compared to conventional tillage management. Some of these advantages include: 1) Elimination of tillage for seedbed preparation, thus conserving time, fuel cost, and equipment, and (2) Conservation of soil and water due to ground cover from the straw.
Weedlcontrol in no-tillage soybeans planted into small grain straw can often get out of hand if proper herbicides and timing of herbicide application are not managed properly. Weeds probably cause the greatest yield loss and is the most devistating pest encountered in soybean farming irrespective of tillage regeime. The objective of this study was to investigate herbicides and no-tillage management variables for control of weeds and treatment influence on yield of soybeans planted in rye straw.
MATERIALS AND METHODS
This study was conducted from 1977 through 1979 at the Green Acres Agronomy farm near Gainesville, Florida. Cobb soybeans were planted into rye straw in late May using a Brown Harden Superseeder minimum tillage planter. Soybeans were seeded in 30 inch rows at 12 seed per foot. Main treatments were no-tillage in-row subsoil versus no-tillage coulter slot-planting. Four sub-treatments were herbicide combinations as shown under Tables 1 and 2. The test was replicated three times. All plots received .25 pounds a.i. paraquat plus 1 pint Ortho x 77 per 100 gallons of water applied post directed when the crop was 14 to 18 inches in height.
Weed populations were estimated at harvest each year and are reported as percentage of the ground covered by weeds. No ground cover of weeds would represent 0% while complete ground cover would represent 100%.
Raymond N. Gallaher and Wayne L. Currey are Associate Professors of Agronomy, Department of Agronomy, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, FL 32611
49




50
RESULTS AND DISCUSSION
Yield 3
Soybean yield was considerably higher than the Florida state average (Table 1). No-tillage coulter slot-planting gave the highest yield in 1977 as compared to no-tillage in-row subsoil. Weather conditions I
in 1977 were such that severe moisture stress occurred all over Florida. Several sources indicated that sufficient rainfall did not occur to seal up the subsoil slots in 1977 and instead of obtaining better soil moisture I
utilization, the reverse occurred. No data is available to substantiate this hypothesis, however, the open slot may have caused soil moisture to evaporate and be lost more easily. Main plot treatments had no 3
affect on yield in 1978 or 1979.
Herbicide treatments had no affect on yield of soybeans in 1977. The area was in bahiagrass (Paspalum Notatum Flugge Var.) sod and was destroyed by tillage in 1976. Weeds were not a big problem in 1977 as in subsequent years. Also bahiagrass reestablishment and competition did not become significant until after the first year. These combined factors are U
throught to be the reasons for all herbicides resulting in similar yield of soybeans in 1977.
A definite trend emerged among herbicide variables in 1978 and 1979. 3
The best treatment (alachlor + metribuzin + glyphosate) gave a threeyear average of 37 bu/A. This was a six bu/A advantage over using glyphosate alone, which resulted in the lowest yield. Applications of oryzalin + metribuzin + paraquat and prodiamine + metribuzin + paraquat were not statistically different in yield from alachlor + metribuzin + glyphosate. i
Ground Cover of Weeds
The percentage ground cover of weeds at harvest time (Table 2) shows i
a strong relationship with yield. As yield increased weed cover decreased. Note that weed pressure was much greater where glyphosate was used alone. All other treatments had the same ground cover of I
weeds at harvest. This differences was due to residual herbicides used in the first three treatments but not in treatment four.
If the three year average yield in Table 1 is plotted against the three year average percentage ground cover of weeds in Table 2 then we obtain a simple change relationship given by the following equation: yield = 38 bushels .23(x change in percent ground cover of weeds). This means that soybean yield was reduced by 0.23 bu/A as the percent ground cover of weeds increased by 1%. If there had been no weeds, yield should have been 38 bu/A. If there had been 30% ground cover of weeds, yield prediction would be 38 bushels .23(30%) or 31 bu/A.
Summary 1
With proper management, no-tillage soybeans in rye straw can be grown successfully. Proper selections and timing of herbicides are critical for successful weed control in no-tillage soybeans. This study shows
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51
that alachlor + metribuzin + glyphosate provided good overall yield and the least competing weeds. Other treatments, using residual herbicides and the contact herbicide paraquat were statistically equal in yield and io weed control to the above treatment. Soybean yield was reduced by almost 1/4 bu/A for each percentage increase in ground cover of weeds.




52
Table 1. Yield as affected by subsoiling and chemical weed control for minimum tillage
soybeans.
1977 1978 1979 3-Year Average
Sub- Sub- Sub- SubTreatment Soil Coul. X Soil Coul. X Soil Coul. X Soil Coul, X
---------------------------------Percent --------------------------------S41 46 40a 34 32 33a 38 31 35a 37 36 37a
2 33 47 44a 32 28 30ab 31 31 31ab 32 35 34ab
3 37 43 40a 30 28 29ab 31 31 31ab 32 34 33ab
4 37 41 39a 29 27 28 b 26 29 28 b 30 32 31 b
S37 44 31 29NS 32 31NS 33 34NS
tl. Alachlor (Lasso) 3 lb. a.i./A + Metribuzin (Sencor 50WP) 0,38 lb a.i./A +
glyphosate (Roundup) 2 lb a.i./A.
2. Oryzalin (Surflan 75W) 1 lb. a.i./A + Metribuzin (Sencor 50WP) 0.38 lb/A a.i. +
paraquat (Ortho Paraquat CL) .5 lb a.i./A + Ortho X-77 added at 1 pt/100 gal, spray.
3. Prodiamine (Rydex) 0.33 lb a.i./A + Metribuzin (Sencor 50WP) .38 lb ai./A +
paraquat (Ortho Paraquat CL) .5 lb a.i./A + Ortho X-77 added at 1 pt/100 gal. spray.
4. Glyphosate (Roundup) 2 lb a.i./A.
+Significant difference between tillage means at 0,05 level of probability,
Means followed by common letters in the same column-are non significant at the 0,05
level of probability.
NS =, Non-significant
Alachlor 2-chloro-2' ,6'-diethyl-N-(methoxymethyl)acetanilide
Metribuzin 4-amino-6-tert-butyl-3-(methylthio)-as-triazin-5(4H)one
Glyphosate N(phosphonemethyl )glycine
Oryzalin 3,5-dinitro-N4,N4-dipropylsulfanilamide
Paraquat 1,1'-dimethyl-4 4' -bipyridinium ion
Prodiamine 2,4-dinitro-N ,N3-dipropy1-6-(trifluoromethyl )-1,3-benzenediamine
I




" 53
I Table 2. Percent ground cover of weeds at harvest of minimum tillage as affected
by tillage and chemical weed control.
1977 1978 1979 3-Year Average
Sub- Sub- Sub- SubSTreatment Soil Coul. X Soil Coul. X Soil Coul. X Soil Coul. X
1-eren-----------------------------------percent-------------------------------------1. 21.3 11.3 16.3 b 12.0 14.0 13.0 b 6.8 12.5 9.7a 13.5 13.8 13.21
2. 25.8, 17.0 21.4 b 15.3 13.0 14.2 b 16.0 18.8 17.4a 19.3 16.3 17.81
3. 22.51 23.8 23.2 b 22.0 12.0 17.0 b 11.3 18.8 15.1a 18,8 18.3 18.61
4. 41.3 26.3 33.8a 61.3 43.8 52.6a 14.5 22.5 18.5a 39.0 28.3 33.7a
X 27.8 19.6NS 27.7 29.7NS 12.2 18,2NS 22,7 18.9NS
I 1. Alachlor (Lasso) 3 lb. a.i./A + Metribuzin (Sencor 50WP) .38 lb a.i./A +
glyphosate (Roundup) 2 lb a.i./A.
2. Oryzalin (Surflan 75W) 1 lb a.i./A + Metribuzin (Sencor 50WP) .38 lb a.i./A +
paraquat (Ortho Paraquat CL) .5 a.i./A + Ortho X-77 added at 1 pt/100 gal. spray.
3. Prodiamine (Rydex) .33 lb a.i./A + Metribuzin (Sencor 50WP) .38 lb ai,/A +
paraquat (Ortho Paraquat CL) .5 a.i./A + Ortho X-77 added at 1 pt/lO0 gal. spray.
4. Glyphosate (Roundup) 2 lb a.i./A.
S Means followed by common letters in the same column are non significant at the I 0.05 level of probability.
NS = Non Significant




SUBSOILING AND MINIMUM TILLAGE OF CORN ON FLORIDA FLATWOOD SOIL
R.N. Gallaher and W.R. Ocumpaugh
INTRODUCTION
Establishing corn (Zea mays L.) in unprepared seedbeds is becoming a widely practiced management procedure. Minimum or no-tillage planting of corn can significantly reduce fuel use and the time required to plant when compared to conventional tillage management. Florida has a widely diverse number of soil types, some of which have produced greater corn yield after in-row subsoiling when compared to a check. Florida flatwood soils are extensive and data on subsoiling and minimum tillage on these soils are lacking. This paper provides and discusses corn data as influenced by tillage on three Florida flatwood sites in 1979. The soil at all locations was a Pomona sand (sandy, siliceous, hyperthermic Ultic Haplaquods) having less than one percent slope.
EXPERIMENTAL PROCEDURE
Three experiments were established in 1979 on soils classified as Pomona sand. These studies were either on or adjacent to the Beef Research Unit of the Institute of Food and Agricultural Sciences, University of Florida, located about 19 km (12 miles) North of Gainesville. All experiments had two corn hybrids ('DeKalb XL78' and 'Asgrow RXll4') as whole plots and in-row subsoiling versus no subsoiling as sub plots. Each was replicated three times. Tillage and planting operations were accomplished with 4600 and 5600 Ford tractors. Brown-Harden two row Superseeder frames were used for planting, one with and one without in-row subsoilers attached. Individual planters were John Deere Flexi 71 units attached to the frame.
In a single pass, corn was seeded in 76.2 cm (30 inches) wide rows at 74,130 seed/ha (30,000 seed/A) with 2.24 kg/ha (2 pound/A) active ingredient (a.i.) alachlor (Lasso) (2-chloro-2', 6'-diethyl-N-(methoxymethyl) acentanilide), 2.24 kg/ha (2 pounds/A) a.i. atrazine (2chloro-4-ethylamino-6-isopropyl-amino-1, 3, 5-triazine) and 2.24 kg/ha (2 pounds/A) a.i. carbofuran (Furadan) (2, 3-Dihydro-2, 2-dimethyl-7benzofuranyl methylcarbamate). Corn on minimum tillage experiments also received in the herbicide tank mix 0.56 kg/ha (0.50 pounds/A) a.i. paraquat plus 0.47 L (1 pint) Ortho X77 surfactant per 378.4 L (100 gallons) of water applied. The herbicides were2applied using 8004 tips spaced 50.8 cm (20 inches) apart at 2.812 kg/cm (40 psi) pressure in a liquid solution of 113.52 L/ha (30 gallons/A) using water as a carrier.
R.N. Gallaher and W.R. Ocumpaugh are Associate and Assistant Professors of Agronomy respectively, Agronomy Department, IFAS, University of Florida, Gainesville, Florida 32611. The use of product trade names does not constitute a guarantee or warranty of the products named and does not signify approval to the exclusion of similar products.
54




55
Experiment one
Land preparation for experiment one included a harrow (2.44 meter
8 foot bushog) operation followed by a moldboard plow (Ford with three 40.6 cm (16 inch) plows) operation on recently cleared land. We then broadcast 56-43.4-232.6-33.6-28 kg/ha (50-38.7-207.5-30-25 pounds/A)
of N"(nitrogen), P(phosphorous), K(potassium), Frit 503 trace elements and Mg(magnesium), respectively and harrowed once more on March 16 prior to planting on March 17. Plot size consisted of eight rows 76.2 meters (250 feet) long. A 23.2 sq meter (250 sq feet) area was sampled from each plot for yield determination on July 6, 1979.
Experiment two
This area had been in corn production in 1977 but was not farmed in 1978. In November of 1978 a light harrow was run over the test site but young blackberry (Rubus sp.) and other weeds were extensive when corn was planted by the minimum tillage procedures on March 17, 1979. Fertilizer was applied at planting in a 20 cm (8 inch) band over the top of the corn row at a rate of 31.4-27-78.2 kg/ha (28-24-69.7 pounds/A) N, P, and K, respectively. The plots were 6 rows wide and 30.48 meters (100 feet) in length. A 9.29 sq meter (100 sq feet) area was sampled from each plot for yield determination on July 6, 1979.
Experiment three
This area was adjacent to experiment two and had the same cropping history. This area was undisturbed, in that it had not been harrowed the previous fall as was the case in experiment two. It was covered with large fruit bearing blackberry briars and covered uniformly with other broadleaf and grassy weeds. Treatment and sampling was the same as for experiment two, however, plot length was 15.24 meters (50 feet) instead of 30.48 meters (100 feet) as for experiment two. Plots were sampled for yield determination on July 9, 1979.
Common practices
Procedures common to all studies included the sidedress application of 168 kg N/ha (150 pounds/A) when corn was 50 cm (20 inches) in height. Near the same time a post direct application of 0.28 kg/ha a.i. paraquat plus 1.121 kg/ha a.i. linuron (Lorox) (3-(3, 4-Dichlorophenyl)-l-methoxy 1-methyl-urea) and 0.47 L (1 pint) Ortho X77 surfactant per 378.4 L (100 gallons of water was made on minimum tillage experiments. Post direct herbicide treatments were not needed on experiment one because of low weed populations associated with the recently cleared land.
Plot weights of whole plants and ears were taken for dry matter, moisture and shelling percent using routine procedures. Forage yields are reported at zero moisture on a dry matter basis and grain adjusted to 15.5%.
Statistical analyses were made using taped programs for a split plot on a programmable calculator. Means were evaluated by F test.




56
RESULTS AND DISCUSSION
Data are given in tables 1 through 3 for yield and other variables. We have indicated treatment differences at the 80% level of probability and above. The 80% level was chosen due to the difficulty of measuring treatment difference with a small number of replications and treatments.
Both hybrids responded to subsoiling for forage yield in all experiments. This was not the case for grain yield. DeKalb XL78 did not respond in experiment two and neither hybrid responded to subsoiling in experiment three. Grain yield was positively related to ear weight and ear weight was larger in the two minimum tillage experiments, (Tables 2 and 3) as compared to the conventional tillage test (Table 1). This was as expected since it has been shown that more soil moisture is available to corn if grown under minimum tillage as compared to conventional tillage. Since subsoiling also resulted in higher yield it can be assumed that this also was beneficial in moisture conservation and possibly better plant root distribution into the subsoil layers.
Subsoiling had the greatest benefit for corn in the conventional tillage study (Table 1). More soil moisture would be lost as a result of extra soil exposure for evaporation and lack of ground cover to reduce runoff and infiltration in the conventional tillage area. The greater response to subsoiling in experiment one indicated a greater need for subsoil water as compared to the no-tillage studies.
Yields in the no-tillage experiments were equal to or greater than in the conventional tillage test. Most inputs were equal except for the extra fertilizer used and extra fuel consumption, and time required to prepare the land for planting in experiment one. Specific fuel consumption and time measurements for various operations have not been made for a Pomona sand but have been measured for other Florida soils. Using average values for fuel consumption and time measures for Florida sandy soils show that the various tillage regimes used in these studies vary widely as follows: (1) Conventional tillage soil preparation and planting would use an average of 34.78 L/ha (3.72 gallons/A) of diesel fuel and would take 241.91 min/ha (97.9 min/A) to perform. (2) Planting with in-row subsoiling into the conventional tillage seedbed would add 5.05 L/ha (.54 gallons/A) fuel used and would require additional time of 12.36 min/ha (5.0 min/A). (3) No-tillage would reduce fuel and time requirements tremendously. No-tillage without subsoiling required an average of 6.55 L/ha (.70 gallons/A) diesel fuel and 77.59 min/ha (31.4 min/A) to plant. (4) No-tillage with in-row subsoiling would add 6.45 L/ha (.69 gallons/A) diesel fuel used and 9.43 min/ha (41 min/A) time to plant corn.
From the fuel and time data given we can note the following: (1) To grow corn as in experiment one (non-subsoiled) it would require five times more fuel than no-tillage (non-subsoiled) as in experiments two and three, (2) it would take over three times more time to establish the crop in the conventional versus no-tillage system, and (3) it would take twice the fuel of that required for no-tillage to plant with inrow subsoiling, but would require only slightly more time to subsoil.




57
If farmers can obtain yields from no-tillage on flatwood soils as we obtained in these studies, significant savings in energy, equipmeat, and labor will result in Florida agriculture. At the same time profits would be higher because of these reduced input costs as well as the extra returns generated from higher yields that would likely Occur.
An additional factor that needs to be considered on flatwood soils is that if heavy rains come after the soil has been cultivated (harrowed aid/or moldboard plowed) it can become so wet during the planting season that it may delay planting. The cultivated soil when wet will not support machinery. This is not a serious problem in minimum tillage situations. Thus in wet years planting time could be delayed from a few days to a few weeks under conventional tillage. Delayed planting often results in reduced yields. Worse still would be to have the soil tilled and the fertilizer cultivated in, ready to plant then get heavy rain that delayed planting two weeks or more as happened at the Beef Research Unit in 1980. No measurements were made, but undoubtedly, considerable N and K fertilizer was lost due to leaching.
IV




58
Table 1. Corn Variables as influenced by subsoiling and corn hybrids grown on a flatwood soil in a conventional tillage seedbed, Gainesville, Florida, 1979. (Exp. 1).
Subsoil Subsoil
Variety Yes No Mean Yes No Mean
Dry forage yield kg/ha Grain yield kg/ha
DeKalb XL78 18,699 15,993 17,346a 7,044a 6,755a+ 6,900
Asgrow RX114 18,650 15,890 17,270a 6,077a 4,708a+ 5,393
Mean 18,675 15,942* 6,561 5,732**
Percentage grain in forage Ear weight in grams
DeKalb XL78 31.8a 32.1aNS 32.0 134 103 119a
Asgrow RX114 30.6a 25.0b* 27.8 130 87 109a
Mean 31.2 28.6 132 95**
Number plants/ha Number ears/ha
DeKalb XL78 57,564 56,531 57,048b 52,828 58,856 55,842a
Asgrow RX114 59,717 65,314 62,516a 52,225 54,378 53,381a
Mean 58,641 60,923NS 52,527 56,617*
Plant height in cm Ear node height in cm I
DeKalb XL78 251a 259aNs 255 81 86 84b
Asgrow RX114 265a 239b++ 252 91 98 95a
Mean 258 249 86 92NS
NS=Non significant + = Significant interaction at the 80% level of probability. ++ = Significant interaction at the 90% level of probability.
* = Significant interaction at the 95% level of probability or between
the tillage treatment. I
**= Significant differences at the 99% level between tillage treatments. letters = Values between hybrids followed by different letters are
significantly different at the 95% level of probability.
Multiply kg/ha by 0.89 to get pounds/A. Multiply number/ha by 0.405 to get numbers/A. Divide grams by 454 to get pounds. Divide cm by 2.54 to get inches.




59
Table 2. Corn variables as influenced by subsoiling and corn hybrids on a flatwood soil in a non-tilled seedbed, Gainesville, Florida, 1979. (Exp. 2).
Subsoil Subsoil
VPriety Yes No Mean Yes No Mean
Dry forage yield kg/ha Grain yield kg/ha
DOKalb XL78 22,221 20,822 21,522a 9,209 9,121 9,165a
Asgrow RX114 18,613 17,668 18,141b+ 7,734 7,539 7,637b++
Mban 20,417 19,245+ 8,472 8,330NS
Percentage grain in forage Ear weight in grams
DeKalb XL78 35.0 37.0 36.0a 153 154 154a+
Asgrow RX114 35.1 36.1 35.6a 145 137 141b
Mean 35.1 36.6NS 149 146NS
Number plants/ha Number ears/ha
DeKalb XL78 6u,OUU 1,blbT 61,138a 60,600 59,200 59,900a Asgrow RX114 55,971 51,666 53,819a 54,895 55,218 55,057a
Mean 58,286 56,671NS 57,748 57,209NS
Plant height in cm Ear node height in cm
DeKalb XL78 272 266 2b9a 97 96 97a
Asgrow RX114 268 252 260a 97 102 100a
Mean 270 259NS 97 99NS
NS = Non significant.
+ = Significant interaction at the 80% level of probability. ++ = Significant interaction at the 90% level of probability.
* = Significant interaction at the 95% level of probability or between
the tillage treatment.
** = Significant differences at the 99% level between tillage treatments. letters = Values between hybrids followed by different letters are
significantly different at the 95% level of probability.
Multiply kg/ha by 0.89 to get pounds/A. Multiply number/ha by 0.405 to get numbers/A. Divide grams by 454 to get pounds. Divide cm by 2.54 to get inches.




60
Table 3. Corn variables as influenced by subsoiling and corn hybrids on a flatwood soil in a non-tilled seedbed, Gainesville, Florida, 1979. (Exp. 3).
Subsoil Subsoil
Variety Yes No Mean Yes No Mean
Dry forage yield kg/ha Grain yield kg/ha
DeKalb XL78 15,542 14,629 15,086a 7,144a 7,232aNS 7,188
Asgrow RX114 16,793 14,751 15,772a 7,389a 6,089a+ 6,739
Mean 16,168 14,690++ 7,267 6,661
Percentage grain in forage Ear weight in grams DeKalb XL78 38.8 41.8a++ 40.3 154a 150aNS 152
Asgrow RX114 37.2 34.9b++ 36.1 162a 130b++ 146
Mean 38.0 38.4 158 140
Number plants/ha Number ears/ha
DeKalb XL78 42,732 46,284 44,508a 47,360 47,683 47,522a
Asgrow RX114 40,364 48,437 44,401a 45,530 46,607 46,069a,
Mean 41,548 47,361NS 46,445 47,145NS
Plant height in cm Ear node height in cm
DeKalb XL78 256 252 254a 85 76 81a
Asgrow RXll4 255 246 251a 99 86 93a
Mean 256 249NS 92 81NS
NS = Non significant. I
+ = Significant interaction at the 80% level of probability. ++ = Significant interaction at the 90% level of probability.
* = Significant interaction at the 95% level of probability or between I
the tillage treatment.
**= Significant differences at the 99% level between tillage treatments. letters = Values between hybrids followed by different letters are I
significantly different at the 95% level of probability.
Multiply kg/ha by 0.89 to get pounds/A. Multiply number/ha by 0.405 to get numbers/A. Divide grams by 454 to get pounds. Divide cm by 2.54 to get inches.
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COMPARISONS OF ENERGY REQUIREMENTS FOR WEED CONTROL IN CONVENTIONAL AND NO-TILLAGE SOYBEANS
J. M. GOETTE, W. L. CURREY, B. J. BRECKE, M. B. GREEN, AND R. C. FLUCKI
ABSTRACT
Comparisons of energy efficiency were made between weed control programs in conventional and no tillage soybean (Glycine max (L.) Merr.) production. Two weed control systems of each of conventional and no tillage soybean production were compared. Calculated energy inputs and measured yields were used to determine the specific energy productivity for each weed control program. Both no tillage operations showed the highest overall energy efficiency with paraquat + oryzalin + metribuzin at planting and metribuzin + 2,4-DB directed post exhibiting the greatest energy productivity.
INTRODUCTION
The weed.control programs in this study were selected to compare the energy efficiences of preemergence and directed post herbicides in no-till soybean.production to that of preplant incorporated herbicides in combination with directed post herbicides or cultivation in conventional production.
Energy is an important factor in determining the efficiency of production. The importance of energy will increase in the future due to rising fuel costs and exhaustion of non-renewable resources. Energy conservation is a majpr reason for the increasing adoption of no tillage production systems.
There are many different energy units used throughout the world. One of the more common units is the joule which is of the metric (SI) system. This report will commonly refer to these energy units as megajoules (MJ) or lOb joules.
Fluck (1979) proposed that a new measure of productivity, the quantity of product per unit of input energy, be designated and that it be termed energy productivity. In the SI system of units, a convenient measure of energy productivity is kilogrammes per megajoule (kg/MJ).
Energy productivity is specific for each agricultural product, location and time. That is, energy productivity can be used only to compare alternative production systems and energy conservation practices which result in the same product, at the same place, at the same time. By calculating the energy productivity of various production systems, the most energy efficient system
may be determined.
I Research Assistant, Associate Professor, Assistant Professor, and Visiting Professor of Agronomy, and Professor of Agricultural Engineering, respectively. Institute of Food and Agricultural Sciences, University of Florida, Gainesville, Florida.
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RESULTS AND DISCUSSION
Results from these four weed control programs indicated that the no-tillage operations produced larger yields and required less energy input than the conventional operations. Therefore, the no-till production systems showed greater efficiency from an energy point of view due to larger values of energy productivity.
Many explanations exist for no-tillage efficiency. Robertson and Prine (1976) and Triplett and Van Doren (1977) listed numerous advantages:
(1) Less fuel is required due to fewer and less energy-intensive
field operations.
(2) Higher yields often result, particularly in dry land farming
and on well-drained land. Evidence of this report supports
the above statement.
(3) Less time and labor are required.
(4) Land use may be intensified.
(5) It is possible to farm lower quality land.
(6) Less erosion occurs.
(7) Moisture is conserved.
(8) Soil structure may be improved.
(9) There is lower investment for machinery.
The no-till weed control program that exhibited thegreatest energy productivity was the combination of paraquat + oryzalin + metribuzin at planting with metribuzin + 2,4-DB directed post. This herbicide program produced an efficiency rating 21.7% greater than that of the highest yielding conventional program and 27.3% greater than that of the lowest yielding conventional program.
The no-till preemergence application of paraquat, alachlor, and metribuzin contributed the second highest energy productivity. This weed control program was found to be 17.8% greater than that of the highest yielding conventional program and 23.7% greater than that of the lowest yielding conventional program which contained two cultivations.
Green and McCulloch (1976) stated that, in general, at least two mechanical weeding operations are required to achieve the effect of one chemical treatment. This statment is supported by the poor performance of the conventional program which contained two cultivations. It produced the lowest yield while requiring the greatest total energy input. When compared to the directed post-treatments in conventional production, the mechanical weeding again proved to be the least efficient. This comparison supports the statement that chemicals are an efficient use of fossil fuel.




63
The purpose of this research was to determine the energy requirements of various weed control programs in no-tillage and conventional production of soybeans and to compare their energy efficiencies.
MATERIALS AND METHODS
Field experiments to evaluate the energy productivity of weed control programs in no-till and conventional soybean production were initiated in June of 1979 at the Agricultural Research Center located in Jay, Florida. The soil type was a Tifton fine sandy loam. Preplant incorporated and preemergence herbicides were applied during the first week in June with the directed-post treatments applied August 1. Soybeans yields for these four weed control programs were obtained in the fall.
The energy inputs for manufacturing soybean herbicides are given in Table 1. This energy input is the product of the energy requirement for manufacturing times the application rate. The weed control programs in no-tillage and conventional soybean production are listed in Table 2. The no-till programs consist of preemergence applications with one program having additional directed-post treatments. The conventional programs include preplant incorporated treatments with the first program containing two cultivations and the second having directed-post treatments. The itemized energy inputs include the energy required for herbicide production, incorporation, cultivation, and application of directed-post treatments. The energy inputs for preplant and preemergence application are included with the incorporation and planting operations.
When examining energy productivity, all inputs of production must be considered. For conventional soybean production, the total energy input less the energy required for herbicide production, application, incorporation and cultivation equals a base energy input of 15,164 MJ/ha. The base energy input includes energy for fertilizer, fungicides, insecticides, labor, and machinery. This value must be added with the individual weed control inputs to give an accurate estimate of the total energy input.
No-till production systems require less energy inputs of production. Fluck and Baird (1980) state that fuel reductions result in an average saving of 1170 MJ/ha. Lower labor requirements also result in a decrease in energy consumption. Elimination of two field operations might reduce labor inputs
by one hour per hectare or labor energy requirements by about 75 MJ/ha. Lower energy requirements for less machinery will be in the order of 100200 MJ/ha. Total energy reductions for limited tillage as compared to conventional cultivation may be in the order of 1395 MJ/ha for the base energy input. This reduction of energy consumption in no-till production results in a base energy input of 13,769 MJ/ha as compared to 15,164 MJ/ha for conventional production systems.
The energy productivity (Table 3) is calculated by dividing the yield (kg/ha) by the total energy input (MJ/ha). Fluck and Baird (1980) state that energy productivity is intended to and can serve as an evaluator of how efficiently energy is utilized in production systems yielding a particular product. This value illustrates the quantity of soybeans produced per megajoule of input energy.




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The findings of this study strongly support the advancement of herbicide weed control programs in no-tillage soybeans over that of conventional tillage practices. The higher energy productivity of weed control in no-till soybeans illustrates the effectiveness of no-tillage in combination with proper weed control programs.
LITERATURE CITED i
1. Brecke, B. J. 1979. Weed Science annual research report. Institute
of Food and Agricultural Sciences, University of Florida.
pp. 79-83.
2. Fluck, R. C. 1979. Energy productivity: A measure of energy utilization in agricultural systems. Applied Science Publishers Ltd.,
England. p. 32.
3. Fluck, R. C. and C. D. Baird. 1980. Agricultural energetics. AVI
Publishing Company, Inc. Westport, Connecticut. pp. 51-54,
145-147.
4. Green, M. B. 1978. Eating oil. Westview Press, Boulder, Colorado. i
5. Green, M. B. and A. McCulloch. 1976. Energy considerations in the
use of herbicides. J. Sci. Fd. Agric. 27:95-100.
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Table 1. ENERGY INPUT FOR SOYBEAN HERBICIDE.PRODUCTION Energy Herbicide1
Rate Rate Requirements Energy Input
Herbicide lb/A kg/ha MJ/kg MJ/ha
Paraquat .25 .28 460 129
Trifluitalin .50 .56 150 84
Alachle 2.0 2.24 280 627
Oryzalin 1.0 1.12 150 168
Metribuzin .50 .56 410 230
2,4-DB .25 .28 87 24
Product of energy requirement times rate of application.




66
Table 2. ENERGY INPUTS FOR WEED CONTROL PROGRAMS IN NO TILLAGE AND CONVENTIONAL SOYBEANS
U
Cultivation (one) 390 MJ/ha Application (one) 73 MJ/ha Incorporation (2-disc) 750 MJ/ha
Weed Control Itemized Energy Subtotal Energy
Programs Inputs MJ/ha Inputs MJ/ha
A. No Tillage
(1) Paraquat pre + 129
Alachlor pre + 627
Metribuzin pre 230 986
(2) Paraquat pre + 129
Oryzalin pre + 168
Metribuzin pre + 230
Metribuzin DP + 230 I
2,4-DB DP 24
Application (DP) 73 854
B. Conventional Tillage
(3) Trifluralin ppi + 84
Metribuzin ppi + 230 I
Incorporation + 750
Cultivations (2) 780 1844
(4) Trifluralin ppi + 84
Metribuzin ppi + 230
Incorporation + 750
Metribuzin DP + 230
2,4-DB DP + 24
Application (DP) 73 1391
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S Table 3. ENERGY PRODUCTIVITY OF WEED CONTROL PROGRAMS IN NO-TILLAGE AND
CONVENTIONAL SOYBEAN PRODUCTION.
Weed Control Yield Total EnergyI Energy2
Program kg/ha Input MJ/ha Productivity kg/MJ
(1) Paraquat +
Alachlor,
Metribuzin 2345 14755 .1589
(2) Paraquat, +
Oryzalin +,.
Metribuzin + Metribuzin +
2,4-DB 2439 14623 .1668
(3) Trifluralin +
Metribuzin +
Cultivations (2) 2063 17008 .1213
(4) Trifluralin +
Metribuz'in + Metribuzin +
2,4-DB 2164 16555 .1307
Conventional Tillage 15,164 MJ/ha + Weed Control Input.
No Tillage 13,769 MJ/ha + Weed Control Input.
2
Energy Productivity = Yield kg/ha
Total Energy Inputs MJ/ha
= Quantity ofsoybeans produced per megajoule of input energy.




ARE NO-TILL MULTICROPPING PRODUCTION METHODS
PROFITABLE FOR FLORIDA FARMERS?1
DAN L. GUNTER, NANCY MCCABE AND RAY GALLAHER
Increasing costs of agricultural inputs, especially energy and credit, are forcing farmers to evaluate their conventional production methods to determine if lower cost practices can be identified. No-till and multicropping are two practices being given increasing consideration. Benefits of these practices have been extolled in many of the agriculture publications. The benefits often mentioned include:
1. better utilization of land,
2. reduced fuel and labor costs,
3. spreading of fixed costs of machinery over more annual hours of use, and
4. possible increased yields.
New planting equipment designed to operate in unplowed stubble or mulch andI improved herbicides to control weeds and grasses reduce the problems farmers have found to be associated with no-till production practices.3
Scientists working for the Institute of Food and Agricultural Sciences (IFAS) at the University of Florida have been conducting research on no-till and multicropping methods for some of the more important Florida field crops.3
The purpose of this paper is to report an evaluation of the profitability of producing corn and soybeans using no-till, multicropping practices. A profitability comparison is also made to conventional corn and soybean production.
PROCEDURES
We used data collected from IFAS experiments which were first conducted during 1978 at the University farm near Williston. Multicropping was used in both the no-till and conventionally produced crops. Rye was harvested as hay and/or grain and followed by either corn or soybeans planted with conventional or notill methods.
Corn and soybeans were no-till planted in a single operation using a two row Brown-Harden Super Seeder with a subsoiler. Conventionally planted corn and soybeans required harrowing, plowing, harrowing and then planting. To compare the profitability of these enterprises we developed budgets which are a systematic listing of income and expenses for a production period. The3
Dan L. Gunter is an Extension Production Economist and Nancy McCabe is an undergraduate student, Food and Resource Economics Department, McCarty Hall, University of Florida, Gainesville, Florida 32611. Ray N. Gallaher is an Associate Professor of Agronomy, Department of Agronomy, Agronomy Research Support Lab, Wallace Building, University of Florida, Gainesville, FloridaI 32611.
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U 69
1 budgets show income, variable costs, harvest costs, fixed costs and net returns.
The budgeted costs are based on 1980 input price levels and the annual ownership
3 and operation costs of the following set of machinery and equipment:
Machinery and Equipment
USED IN NO-TILL USED IN CONV.
PRODUCTION PRODUCTION
Tractor, 55 hp X X
Truck, 2 ton X X
Grain Combine X X
Sprayer X X
IPlanter X
Super Seeder 2 row x x
MB Plow (4) x
Harrow x
IFertilizer Spreader X X
3 ESTIMATED COSTS FOR SOYBEANS
The budget for conventionally tilled soybeans is shown in Figure 1. Yield I from the experiment was 29 bushels per acre, variable costs are $78.87 and
harvest costs, which include labor and operating expenses associated with the machinery, are $7.81 per acre. The total variable costs which can be thought
of as "out-of-pocket" expenses totaled $86.68. The fixed costs are $21.52 and include the normal "DIRTI" five expenses associated with ownership of
machinery and equipment. The DIRTI five are: Depreciation, Interest, Repairs, Taxes, and Insurance. Total per acre costs are $108.20, which subtracted from
gross receipts leaves a net return to land and management of $65.80 per acre.
Budgeted costs and returns for no-till soybeans are shown in Figure 2. The
net returns for no-till production are $127.45 as compared to $65.80 using
conventional practices. As expected, machinery and tractor costs are lower
using the no-till practices. The addition of Furadan almost offsets the cost
savings from reduced machinery usage; however, increased yield is attributed I to its use. The difference in net revenue seen by comparing the budgets is
due to difference in yields. The no-till production method resulted in a 10
3 bushel higher yield than conventionally produced soybeans.
ESTIMATED COSTS FOR CORN
1 Budgets for no-till and conventionally produced corn are shown in Figures 3
and 4. The revenue and costs for alternative corn production methods are:
INO-TILL CONVENTIONAL
- Dollars- -- -Revenue 263.25 256.50
Total Costs 156.77 166.04
Returns to Land and
3Management 106.48 90.46




CONVENTIONAL TILL SOYBEANS IN RYE STUBBLE 70 1
WELL DRAINED ACIDIC SANDY LOAM
LEVY COUNTY# 1980 PRICES
PRICE OR VALUE OR
UNIT COST/UNIT QUANTITY COST
Io GROSS RECEIPTS FROM PRODUCTION $ I
BUe 6.00 29.00 4
TOTAL 1.
2. VARIABLE COSTS
PREHARVEST s
SOYBEAN SEED BU. 13.,00 1.00 13*00
TOXAPHENE LBS. 0.77 4.00 3.08
PARAQUAT PT. 5.30 2.50 13.25
LASSO LBS. 4.50 2.00 9.00
LEXONE LBS. 8.75 0*38 3.32
BASAGRAN QT. 7.75 2.25 17.44
ORTHO X 77 PT. 1.75 0.67 e1.17
INNOCULANT BU. 1.70 1.00 1.70 g
MACHINERY ACRE 2.46 1.00 2.46
TRACTORS ACRE 5.11 1.00 5.11
LA3OR(TRACTOR & MACHINERY) HOUR 3.50 1.65 5.79
INTEREST ON OP. CAP. DOL. 0.14 25.32 I
SUBTOTAL* PRE-HARVEST S .
-ARVEST COSTS $
MACHINERY ACRE 5.47 1.00 5.47
LABOR(TRACTOR &F MACHINERY) HOUR 3.50 0.67 _f!34
SUBTOTAL. HARVEST $ e$O
TOTAL VARIABLE COST $ 86.68
I
3. INCOME ABOVE VARIABLE COSTS $ 87.32
4. FIXED COSTS $
MACHINERY ACRE 17.21 1.00 17.21
TRACTORS ACRE 4.31 1.00 4__AI I
TOTAL FIXED COSTS $T 2.52
5. T3TAL COSTS S 108.20
6. NET RETURNS S 65.80
BROWN-HARDEN SUPERSEEDER
COBB SOYSEANSo SUBSOILED
NANCY MCCABE RAY GALLAHER 3/10/80
BUDGET IDENTIFICATION NUMBER--- 124438040 10118 ANNUAL CAPITAL MONTH 11
PROCESSED BY FARM SYSTEMS LAB FOOD & RESOURCE ECON. DEPTeU. OF FLORIDA PROGRAM DEVELOPED BY DEPT. OF AGo ECON. s OKLAHOMA STATE UNIVERSITY DATE PRINTED: 30 APRIL 1980 1
Figure 1.
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NO-T I L L, SOYaEANS IN RYE STUBBLE 71
WEL DRAINED ACIDIC SANDY LOAM LEVI' COUNTY, 1980 PRICES
PRICE OR VALUE OR,
UNIT COST/UNIT QUANTITY, COST
1, GROS$,RECEIPTS FROM PR0DVCT-ION suo. 6*00 39000 234*00
TOTAL s 234*00
2,0_ VAR.11A,8 ,E COSTS
PREHARVEST
SOYBEAWSEED, Buo 13*00 1000 13*00
TOX4PHENE L8So 0077 4*00 3*08
PARAQUAT, PTo 5*30 2*50 l3o 25,:
L*$,,SQ,, LBSo 4e5O 2*00 9*00,
LEXONE, LBSs, 8*75 0*38 3*32
BAsAORAN QTo 7075 2*25 17*44
ORTHO, X 77 PTo 1*75 0*67 tot?
,Ui,,ANT,, BUS 1*00 1*70
INNQC Is70
FURADW LBS* 0*72 tosoo 7*20,
.JNERYt ACRE 1600 2*01
MACH, 2*01
TRACTORS, ACRE 2*66 1000 2o66
LASORCTRACTOR: F, MACHINERY) HOUR 3*50 0986 3*02
INTERESTi ON, OPo CAP* DOL* 0014 27*11
S.UBTOTAL9 PRE-HARVEST *64
HARVEST COSTS s
MACHI.NERY: ACRE 5*47 1*00 59,47"
LABOR(TRACTOR. MACHINERY) HOUR 3*50 0*67 ___4Aa
SV5TOTAL9 HARVEST $ odv
V,,AR $ 88*45
TOTAL UABLE. COST
3* I.NCPMe : ABOVE VARIABLE COSTS. S 145*55
4*, ': VXED,, CO$Ts
MACHINERY ACRE 15o86 1000 15sa6
TRACTORS ACRE 2. 25 t*00
TOTAL, Fl ,XED COSTS, $
59, TOTAL CPSTS, S 106*55
6a-, NET',: R.TURNS, S 1271o 45
BRj3W+--HAR0,EN, SUPERSEEDER
SPYA3F,,ANSp.:, SUBSDILED* WITH FURADAN
N&NCY- MCCA ,SJE; RAY GALLAHER 3/10/80
BVOGET IO,&NTjf!ICATIOW NUMSER --- 124438040 101-18 ANNUAL, CAPITAL, MONTH Lt
PROC ESSED- BY FARM. SYSTEMS, LAB, FOOD RESOURCE ECONs DEPT*.9U9 OF FLORIDA',, PRO.qAAfC, DEVELOPED, BY ; IDEPT,* OF AG9 ECON* 9, OKLAHOMA STATE UNIVERSITY DATE, PRINTED: 30 APRIL 1980
Figure 2.




NO-TILL CORN GRAIN IN RYE HAY STUBBLE 72 1
WELL DRAINED ACIDIC SANDY LOAM
LEVY COUNTY, 1980 PRICES
PRICE OR VALUE OR
UNIT COST/UNIT QUANTITY COST
Ie GROSS RECEIPTS FROM PRODUCTION $ I
CORN BU. 2.25 117.00 $26
TOTAL S 263.25
2. VARIABLE COSTS PREHARVESTs
CORN SEED LBS. 0.85 19.00 16.15
N&P&K CWTo 6.00 6.00 36.00
NITROGEN LBS. 0.24 120.00 28.80
FURADAN LBS. 0.e72 20.00 14.40
ATRAZINE LBS. 1.83 2.00 3.66
PARAQUAT PT. 5.30 1.50 7.95
ORTHO X 77 PT. 1.75 0.66 1.15
LOROX LBS. 4.50 1.00 4.50
MACHINERY ACRE 2.06 1.00 2.06
TRACTORS ACRE 3.36 1.00 3.36
LABOR(TRACTOR & MACHINERY) HOUR 3.50 1.09 3.80
INTEREST ON OP. CAP. DOLe 0.14 41.78 5&85
SUBTOTAL, PRE-HARVEST SF12768
HARVEST COSTS S
MACHINERY ACRE 6.45 1*00 6.45
LABOR(TRACTOR & MACHINERY) HOUR 3.50 0.85 2*97
SUBTOTAL, HARVEST s 9.42
TOTAL VARIABLE COST $ 137.10
3. INCOME ABOVE VARIABLE COSTS $ 126.15
4. FIXED COSTS $
MACHINERY ACRE 16.84 1.00 16.84
TRACTORS ACRE 2.83 1.00 0g3
TOTAL FIXED COSTS S 19.67
5. TOTAL COSTS S 156.77
6. NET RETURNS S 106.48
BROW4-HARDEN SUPERSEEDER
FUNKS G-4507 CORN* SUBSOILED, 5-10-5 NANCY MCCABE RAY GALLAHER 3/10/80
BUDGET IDENTIFICATION NUMBER--- 104438040 10118 ANNUAL CAPITAL MONTH 7
PROCESSED BY FARM SYSTEMS LAB FOOD & RESOURCE ECON. DEPTeeU. OF FLORIDA PROGRAM DEVELOPED BY DEPT. OF AGo ECON. OKLAHOMA STATE UNIVERSITY DATE PRINTED: 30 APRIL 1980 F
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Figure 3.
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CONVENTIONAL TILL CORN IN RYE HAY STUBBLE 73
WELL DRAINED ACIDIC SANDY LOAM
LEVY COUNTY. 1980 PRICES
PRICE OR VALUE OR
UNIT COST/UNIT QUANTITY COST
1. GROSS RECEIPTS FROM PRODUCTION $
CORN B3U. 2.25 114.00 S
TOTAL S 256.50
2. VARIABLE COSTS
PREHARVEST $
CORN SEED LBS. 0.85 19.00 16.15
N&P&K CWTo 6.00 6.00 36.00
NITROGEN LBS. 0.24 120.00 28.80
FURADAN LBS. 0.72 20.00 14.40
ATRAZINE LBS. 1*.83 2*00 3.66
PARAQUAT PT. 5e30 1.50 7.95
ORTHO X 77 PT. 1.75 0.66 1.15
LOROX LBS. 4.50 1*00 4.50
MACHINERY ACRE 2.52 1.00 2.52
TRACTORS ACRE 5.81 1.00 5.81
LABOR(TRACTOR & MACHINERY) HOUR 3.50 1.88 6.58
INTEREST ON OP. CAP. DOL. 0.14 42.99 (a
SUBTOTAL, PRE-HARVEST $ 133.*3
HARVEST COSTS $
MACHINERY ACRE 6.45 1.00 6.45
LABOR(TRACTOR & MACHINERY) HOUR 3.50 0.85 $ a97
SUBTOTAL. HARVEST S 942
TOTAL VARIABLE COST $ 142.95
3. INCOME ABOVE VARIABLE COSTS $ 113.55
4. FIXED COSTS $
MACHINERY ACRE 18.19 1.00 18.19
TRACTORS ACRE 4.90 1.00 4&
TOTAL FIXED COSTS
5. TOTAL COSTS $ 166.04
6. NET RETURNS S 90.46
BROWN-HARDEN SUPERSEEDER
FUNKS G-4507 CORN, SUBSOILED. 5-10-5 NANCY MCCABE RAY GALLAHER 3/10/80
BUDGET IDENTIFICATION NUMBER--- 104438040 10118 ANNUAL CAPITAL MONTH 7
PROCESSED BY FARM SYSTEMS LAB FOOD & RESOURCE ECON. DEPT.,U. OF FLORIDA
PROGRAM -DEVELOPED BY DEPT. OF AG* ECON. OKLAHOMA STATE UNIVERSITY DATE PRINTED: 30 APRIL 1980
Figure 4.




741
Yields observed were three bushels per acre higher in the no-till field while the machinery operating costs were lower accounting for the $16.02 difference in net revenue.
FUEL AND LABOR COSTS COMPARISONS
With increased interest in energy conservation, producers can compare fuel use for the alternative production methods. Figure 5 shows the gallons per acre of gasoline and diesel fuel. The no-till practices require almost three gallonsI less fuel than the conventional practices. This translates into more than a $3 per acre cost savings at 1980 fuel price levels. However, fuel savings alone may not provide enough incentive for farmers to adopt a new set of cultural practices.
In addition to the fuel savings, labor and machinery requirements are reduced with no-till practices. Figure 6 shows a labor savings of almost 0.8 of anI hour/acre for both corn and soybeans produced using no-till production methods. Likewise, machinery hours required are lower using no-till. For example, the variable costs per acre for the tractor is $5.11 for conventionally planted soybeans and $2.66 for no-till (Figure 7). The variable costs for the tractor for no-till corn production is $3.36 per acre as compared with $5.81 if produced conventionally.3
PROFITABILITY OF MULTICROPPING
Other fixed or variable cost comparisons can be made, but the real test is whether or not net returns are higher? If we compare net returns per acre where corn and soybeans are multicropped with hay, yielding both rye grain and hay, the total net returns are as follows:
NO-TILL CONV. TILL NO-TILL CONV. TILL
CORN CORN SOYBEANS SOYBEANS
Single crop $106.48 $ 90.46 $127.45 $65.80
Rye grain and hay 14.29 14.29 14.29 14.29
Total returns/acre $120.77 $104.75 $141.74 $80.09
CONCLUSIONS
The results of the experiments and budget analysis show that no-till and multicropping are more profitable than conventional cultural practices to produce the same crops. Differences in profits are due to reduced costs and higher yields using no-till production.3
These results stem from one year's experiment. Further experimental work needs to be undertaken to evaluate the effectiveness of no-till practices under farm conditions. Farmers considering no-till practices should do some careful feasibility analyses before they trade their mold board plow and disk for onepass planting equipment.




75
II
1 GallIons
110 8-0Gas
_ _1 2Diesel
0
no- conv. no- cony.
till till till till
CORN SOYBEANS
Figure 5. Fuel Used Per Acre.
Hours Dollars
Labor 3.0 6
1 5
2.0 4
3
1.94 2.75 1.53 2.32 3.36 5.81 2.66 5.11
11.0 2
no- conv. no- cony. no- conv. no- conv.
till till till till till till till till
CORN SOYBEANS CORN SOYBEANS
Figure 6. Labor Requirements For Figure 7. Variable Costs of
Conventional and No- Tractor Per Acre.
Till Corn and Soybeans.




ALTERNATIVE TILLAGE IN JEFFERSON COUNTY, FLORIDAU
Larry A. Halsey and Phil Worley
Pine Seedling No Til Site Preparation Demonstration
A significant portion of the pine timber and pulpwood industry in North Florida is on farm land. Private landowners receive technical assistance from the Florida Department of Agriculture, Division of Forestry,I as well as the County Cooperative Extension Service.
It is estimated that in Jefferson County 20% of the acreage planted in relatively small blocks by private landowners is on abandoned sod orU pasture. Various methods of conventional site preparations are employed, including plowing and discing, roto-tilling, or bedding. All constitute a significant portion of the total cost of planting pines. SeedlingsI
occasionally are planted in sods with no mechanical preparation. Pines planted directly in sod or in poorly prepared sites must compete with extensive grass root systems for moisture and nutrients during estab-I lishment and early growth years.
The Forester and the County Extension Director initiated a demonstration "no-till' pine seedling block to determine if chemical site preparationI would eliminate a number of the production problems associated with conventional methods.
Together with Kent Frost, Product Development Specialist of Monsanto, and landowner Ferd Naughton, a 1.25 acre site was selected for the demonstration, The site was an abandoned Pensacola Bahiagrass pasture.I Roundup (glysophate) herbicide was applied at 3 pounds active ingredient per acre (broadcast basis) over 4 foot strips on 12 foot middles on October 22, 1979. Seedlings were transplanted in the herbicide treated strips on 12' x. 5' spacings on January 29, 1980. Spring regrowth of the sod was uniform in the untreated middles between treated strips. Perennial grass control under the treatment approached 100%, with virtually no regrowth. Germination of spring annual weeds in theI strip was observed. As of the middle of April, following the January planting, a preliminary estimate of seedling survival was 97%.
The site was established on small acreage for observation only. On the basis of the apparent effectiveness of this chemical site preparation methods, a follow-up trial on 8-10 acres is anticipated in fall and winter of 1980-81. Side-by-side plantings under conventional site preparation and Roundup treatment will be conducted. The following data will be compiled in the experiment: 1) Comparative fuel consumptions of the various techniques; and equipment, material, labor, andI other costs for accurate budget comparisons. 2) Penitrometer comparisons
Larry Halsey is County Extension Director, Jefferson County, Cooperative3 Extension Service, IFAS, University of Florida. Phil Worley is County Forester, Jefferson County, Division of Forestry, Florida Department of Agriculture and Consumer Services,
76g




1 77
3 of the various site preparations methods, as an index of the ease of
entry of the coulter of the seedling planter unit. 3) Growth characteristics at various intervals following planting, as well as survival and
mortality counts. 4) Observations of root systems of sample seedlings
under each of the various preparation methods.
Assumed advantages of the "no-till' or chemically prepared site include reduction of cost of site preparation, better survival and early growth
due to reduced competition for nutrients and moisture, and reduced erosion and pollution from runoff due to the mulch cover. It should be
noted that the Roundup label for use does not include this specific
application. The trial is being conducted in cooperation with Monsanto
Company representatives for experimental use only.
Minimum Tillage in Row Crops
I During 1978, 135,163 acres of cropland on 2,135 farms in the United
Stat es were assisted through cost share practices involving conservation
tillage systems (SL9) under the Agricultural Stabilization and ConserI vation Service (USDA-ASCS). In Florida, 1978 acreage totaled 535 acres
on three farms. In 1979, 37 farms received cost-share assistance under Agricultural Conservation Program (ACP) totalling 2,182 acres to demonstrate minimum or reduced tillage systems in farming. Jefferson County growers are receiving cost-share on 5 farms with over 320 acres in 1980,
for minimum tillage demonstrations, with total acreage in non-conventional
3 planting or tillage at 3-4,000 acres.
Jefferson County is located along the Florida-Georgia border. Farm land is gently sloping to hilly, with predominate soil type of Ultisols, with I sandy to loamy sand textures of 6.5-8% clay fraction and 2-4% organic
matter. Corn, soybeans, peanuts, tobacco and small grains for seed and forage are the main agronomic crops. Up to 25,000 acres of small grains
or small grains with clover are planted annually for winter and spring
grazing. Corn and soybean crops often are planted behind winter annual
pastures. Corn under better than average high yield management yields
80-85 bu/A; soybean yields of 30-33 bu/A are normal. Both crops are planted under minimum tillage; however, a yield history using reduced
tillage is unavailable.
I Various alternative planting and tillage systems are currently being
employed, from strict "no-till' planting in rye or oats in an absolute "once over" operation to discing once or twice prior to planting with
no-til equipment. Reduction of erosion, reduction of time spent in
planting, reduction in fuel consumption and increased moisture availability during droughty periods around corn tassle and silking stage are most often referenced by farmers using reduced tillage m ethod s as I justification for employing the systems. Farmers are assisted in alternative tillage techniques by the ASCS, the Soil Conservation Service,
* and equipment and chemical suppliers.




MINIMUM TILLAGE DEMONSTRATION PROJECT AGRICULTURAL CONSERVATION PROGRAM (ACP) By
Betty P. Jones, County Executive Director, Alachua County ASCS Office
ACP Program ObjectivesI
The Agricultural Conservation Program (ACP) provides cost-sharing as an incentive to encourage farmers and ranchers to carry out conservation measures that:
1. control erosion and sedimentation from agricultural
land and conserve the water resources on such land;
2. control pollution from animal wastes;
3. conserve wildlife habitat;
4. facilitate sound resource management systems through
soil and water conservation;I
5. contribute to the national objectives of assuring a
continuous supply of food and fiber necessary for theI
maintenance of a strong and healthy people and
economy; andI
6. assures performance of the type conservation measures
needed to improve water quality in rural America.
ACP is a joint effort by agricultural producers and GovernmentI to restore and preserve the environment and basic land resources. Cost-share assistance is available under annual or long-term agreements.I Program Administration
The ACP is administered by Agricultural Stabilization and Conser-I vation (ASC) State, county and community committees, working under the general direction of the Agricultural Stabilization and Conservation Service (ASCS) of the U.S. Department of Agriculture. County andI community committee members are elected by farmers within the local county. Funds for cost-sharing are appropriated annually by the Congress. In recent years, the appropriation has been about $190,000,000.
The ASCS county committee in the local county approves cost-sharing on the basis of requests filed by individual producers. After receiving the official practice approval, performance is done according to specifications developed for the specific practice. All expenses incurred during performance are paid by the farmer. Later, after the practice has been certified as being performed according to practice specifi-I cations, the farmer is reimbursed on an average of from 50 to 75 percent of the out-of-pocket cost of performing the practice.
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1 79
Technical Assistance for Farmers
Farmers are provided necessary technic al assistance to perform
engineering type practices by the Soil Conservation Service (SCS).
Forestry practices are performed under the supervision of the
Florida Division of Forestry personnel located in the county where
the participating farm is located.
3 Demonstration Project Concept
Demonstration type special projects are authorized under the
3 ACP. The purpose of such projects is-to help achieve enduring soil
and water conservation and environmental benefits through the use of
innovative, up-to-date methods for treating conservation problems.
Cost-share assistance is provided under approved projects as an
incentive to encourage farmer participation.
3 Alachua County Demonstration Project
Based on past experience, farmers generally consider minimum
tillage farming ineffective and conducive to crop failure. With
the availability of existing herbicides, insecticides, and pesticides,
and improved planting equipment, the Alachua County ASC Committee
recognized the potential and the advantages of conservation tillage
farming. The Committee, working closely with the Alachua County
I ACP Development Group, recommended the special project to the Florida
State ASC Committee for approval and funding. The project was designed to demonstrate on a community-wide basis the techniques to be I followed when using a minimum tillage operation to grow corn and
soybeans.
Cost-share assistance was provided under the project for farmers
to utilize ACP practice SL9 Conservation Tillage Systems. (See Exhibit 1 for practice specifications.) A 70 percent cost-share
rate was approved which reimbursed the participating farmer for most of*-the out-of-pocket expense incurred above those expenses normally
associated with "standard" row-cropping methods.
3 In order for farmers to become familiar with and to utilize the
most recent developments in multi-cropping minimum tillage and notillage, a farm visit was made to each participating farm to inspect
the fields and to develop a plan of operation. The plans were developed in consultation with Dr. Raymond Gallaher, Associate Professor*
of Agronomy, Institute of Food and Agricultural Services, University
of Florida; the Cooperative Extension Agent; and the SCS District U Conservationist, and included specific recommendations for farmers
to follow in planting and providing necessary weed control (see Exhibit 2). A
follow-up inspection was made by ASCS to check compliance.
Farm tours were held in connection with the project to demonstrate
planting techniques, and to evaluate plant growth and weed control
* during the growing season.




80
Farmer Participation3
A total of 20 farmers participated in the demonstration project. These producers grew 940 acres of corn and grain sorghum and 412 acres of soybeans. Yields were comparable to those for crops grown usingI the "standard" row-cropping system.
SummaryI
Participating farmers were generally successful in carrying out their first-year minimum tillage operation. Yields were satisfactory. Most farmers reported a reduction in fuel cost. However, several farmers indicated that fuel savings were offset by the increased expense incurred for weed control. Overall, most participating farmers believe crops can be grown with less expense using multi-I cropping minimum or no-tillage systems than with the "standard" row-cropping system.
Additional experience is needed, however, for producers to realizeI the maximum benefits. They believe that the system should be tested over a period of years -- i.e. three to five years -- in order for them to assess benefits. Some farmers are concerned about the impactI that a wet growing season or an unusual dry growing season would have on yields. Most participants believe that weed control would be a serious problem during wet years.
The SL9 Conservation Tillage System ACP practice specifications have been changed to permit farmers to receive cost-sharing for three consecutive years. This change will permit farmers to do demonstrationI planting to help them further evaluate minimum tillage operations, to gain the necessary experience, and to develop techniques that will. be most effective under the system.I
Acknowledgments: The'author and the Alachua County ASC Committee
wish to express their appreciation to Dr. Raymond
N. Gallaher, Coordinator, Agronomy Research Support
Laboratory, University of Florida; Mr. A. T. Andrews,
Alachua County Agent; and Norman Porter, SCS
District Conservationist for their technical assis-I
tance; and to those participating farmers who were willing to expend their resources at considerable risk to demonstrate conservation tillage systems
during the 1979 crop year. We learn by doing.
Thank you for sharing your experience with
Alachua County farmers.3




1 81
I IEXHIIT 1
1 L9 CONSERVATION TILLAGE SYSTEMS
A -Purpose. To demonstrate a method of installing tillage
systems and residue management systems of farming that
I Protect soil from wind and water erosion and improve
soil permeability.
2 Prevent or reduce pollution from sediment and chemically
I 'contaminated runoff from agricultural non-point sources.
B Applicability. To cropland needing erosion or sediment
I control while being devoted to the production of intertilled
or small grain crops.
3C Policies.
1 Cost-sharing is not authorized where the farmer has already adopted a satisfactory conservation tillage system of farming.
2 Cost-sharing for this practice may be approved for no more than 3 years with the same person.
3 The land involved must be protected by crop residue,
temporary cover, or other permitted management methods from harvest until the next planting. 54 Eligible tillage operations may consist of:
a Chisel plowing with other limited operations, or Ib Plow-plant, or
c Light tillage without plowing, or Id Approved slot or strip tillage operations ahead
of planting, or
5e Planting on chemically killed sods, or
*f Other similar methods.
5 All tillage operations must be performed as nearly as practicable on the contour or parallel to terraces, except where the committee determines that this is not necessary.




82
EXHIBIT I
6 Chemicals used in performing this Practice must be
Federally, State and locally registered and must be applied strictly in accordance with authorized uses directions on the label, and other Federal or State
policies and requirements.
7 Cost-sharing is not authorized for designated setaside acreage.
8 Cost-sharing is not authorized for acreages where
the crop is cultivated unless prior approval of the method of cultivation is approved in advance by the
county committee.
D Specifications.
1 Performance of this practice shall be carried out
according to the plan developed in consultation
with the Cooperative Extension Agent, a representative of the Institute of Food and Agricultural Sciences, Department of Agronomy, University of
Florida, and the SCS District Conservationist.
2 Cost-sharing is authorized on a per-acre basis for
the following:
a Planter and related equipment. (Excludes
tractor).
b Planting operation. (Includes tractor and
labor).
c Applying herbicide. (Includes material).
d Insecticide -- material only.
e Applying post directed application of
herbicide. (Includes material).
3 Performance shall be verified by a representative
of the county committee before approval of costshare payment.
E Maximum Cost-sbare Rates.
1 Regular Rates.
a 3.50 per acre for planter and related equipment.




EXHIBIT 1 83
b $ 4..20 per acre for planting.
c $12.25 per acre to apply herbicide.
d $ 8.40 per acre for the insecticide.
e $ 7.70 per acre to apply post directed
application of herbicide. 2 Rates for Low-income Farmers.
a $ 4.00 per acre for planter and related
equipment.
b $ 4.80 per acre for planting.
C $14.00 per acre to apply herbicide.
d $ 9.60 per acre for the insecticide.
e $ 8.80 per acre to apply post directed
application of herbicide.




84
EXHIBIT 2
CONSERVATION TILLAGE SYSTEMS
NAME FSNI
Performance of practice SL9 must be carried out according to a plan 3
developed by ASCS in consultation with the Extension Agent; Department of Agronomy, University of Florida; and the SCS District Conservationist. The following recommendations are to be used as a guide. If for any 3
reason they cannot be followed, contact the County Executive Director for other recommendations. Crop: I
Acreage: Photograph Number:
Irrigated: LIII
Non-irrigated: f --J 3
Succeeding Crop or Land Use:
I
Contour Planting:
Conventional Planting: Apply Herbicide: 5
Suggested Material: 1/
Apply Insecticide: I
Suggested Material: 1/ Apply Postemergency Herbicides:
Suggested Material: 1/ 3
1/ Identify material that should be used for the crop to be planted.
Attach any pamphlet, written guidelines, etc., applicable to the
use of the material to the farmer's copy of the plan before delivery
to the farmer.
I
I




85
EXHIBIT 2
Equipment to be Used: Land Preparation Authorized:
General Comments and Additional Guidelines:




ESTABLISHMENT OF LEGUMES IN BAHIAGRASS SOD
R. S. KALMBACHER
Bahiagrass (Paspalum notatum) is widely grown from Texas through the Carolinas, and in Florida is a major pasture grass. It is a tough competitor ihich forms an extremely dense sod crowded with stubby stolons. Bahiagrass is popular because it resists encroachment from weeds, has few disease and insect problems, withstands close grazing, establishes from seed, and does not require high soil fertility. However, grazing studies indicate that bahiagrass is lower in nutritional value when compared with bermudagrass or digitgrass. By midsummer protein and digestibility are low, suggesting that animal intake and performance are adversely affected. In addition bahiagrass is a warm season species that produces 85% of its annual dry matter from May to October. In spite of the valuable attributes of bahiagrass its forage quality is low, and it produces little winter forage.
An ideal method of overcoming these deficiencies is to manage bahiagrass with legumes that provide needed quality and biological nitrogen. At present there are no commercially available perennial legumes adapted to south Florida, but ranchers can use a combination of winter and summer annual species. Florida's summer annual legumes are jointvetch or aeschynomene (Aeschynomene americana), hairy indigo (Indigofera hirsuta), and alyce clover (Alysicarpus vaginalis), and the winter species (which act as annuals in south Florida) are alfalfa (Medicago sativa), red clover (Trifolium pratense ) and white clover (T. reopens .
Since natural reseeding is not always reliable with summer annuals or impossible with most winter annuals (except Dutch clover), reseeding is a frequent practice. Establishment by conventional tillage, which involves chopping or disking, is expensive and energy intensive. An alternative is sod-seeding, which Kentucky workers have shown to use only 20% of the energy input of conventional (prepared seedbed) tillage. However, widespread use of sod-seeding in Florida has been limited by a low probability of success in establishment. At the University of Florida's Ona Agricultural Research Center in south Florida considerable research effort has been devoted to sod-seeding in the past 4 years. We have identified several reasons why legume stands often fail even when water and fertility are adequate.
Forage legumes are slow to establish, and it is extremely important to control bahiagrass competition. A grass competes with a developing legume seedling for light, water, and nutrients: in this order of importance. Although little is known about the competitive effects for water and
nutrients, we have found that having sufficient light available to legume
w R. S. Kalmbacher is Assistant Professor of Agronomy, Ona Agricultural
Research Center, Ona, Florida 33865.
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87
seedlings when they emerge is quite important. Twenty five percent shade did not inhibit aeschynomene seedling growth, and seedling weight was equal to that of plants grown in full sunlight, but when 90% of the light was shaded from aeschynomene seedlings, there was: a 94% reduction in seedling weight; a 45% reduction in weight from seedlings grown under 73% light reduction; and a 19% reduction in seedling weight was found when plants were grown under 55% light reduction.
There are two forms of competition from bahiagrass: 1) competition from previous grass growth present at the time of seedling emergence; and 2) competition resulting from new grass growth during seedling development. Sod management for these forms of competition is different for -winter and summer annual legumes.
Controlling competition before seeding.
Removal of sod cover can be accomplished in several ways, and the choice may be dictated by economics. Some alternatives are disking, mowing, grazing, and fire.
When bahiagrass sod was heavily disked and seeded in early December to red or white clover as compared to drilling seed directly into a thick, untreated sod, the average dry matter yield of the legumes after 2 years was 27% lower in the drilled plots as compared to disk and broadcast seeded plots (Table i). The number of legume seedlings was 52% higher in the disk and broadcast plots. In another study aeschynomene yields were also much greater where bahiagrass was heavily disked as compared to drilling in untreated grass (1300 vs 600 kg/ha). The reason for the difference was the removal of the bahiagrass canopy by disking. Since most sod-seeding drills simply cut a slot in the sod and deposit the seed with a minimum of disturbance, they do not remove the grass canopy. If a drill is used or if there is too much cover to allow for a good disking, then some other sod canopy elimination practices must be used.
Table 1. Comparison of method of seeding on dry matter yield of red and
white clover in bahiagrass sod. Ona ARC. 1977-78.
Year Zip(R) Sod Seeded Disk and Broadcast
3--------------- kg/ha -------------------1977 3500 6230
1978 5500 6030
Average 4500 6130
Harvesting excess forage as hay is best, as this justifies cost of mowing and eliminates the cover. Mowing seems to defeat the purpose of sod-seeding as it requires more time and energy, and the thatch can result in as much competition as uncut grass.




88 5
I
Grazing is an excellent alternative, and research has shown that yields of red and white clover seeded in bahiagrass that had been grazed to a 5 cm (2 inch) stubble were equal to the yield of legumes seeded in I
a bahiagrass sod which had been burned. Burning has most often resulted in the best legume stands in our research. Grazing is probably a more useful tool for removing sod cover before seeding winter legumes because i
after weaning calves in the fall, cows can be concentrated on bahiagrass until the canopy is removed. In June when summer annuals are seeded, the nutritional requirement of cows with calves is probably too high to 3
allow the kind of prolonged bahiagrass grazing which promotes good summer annual legume growth. When compared with burning prior to seeding, grazing as a method of canopy elimination resulted in aeschynomene stands and yields that were comparable. Grazing or disking, followed by broadcasting I
seed resulted in 1500 and 1300 kg/ha, respectively, vs 600 kg/ha for untreated bahiagrass. 3
Fire is an excellent way to prepare bahiagrass for inter seeding of legumes. Often a dense bahiagrass canopy can be burned after a frost in December, but sometimes chemical desiccation is necessary. The herbicide Paraquat(R) has been applied at 0.56 kg/ha (0.5 lb/A) to kill and dry out the canopy in order to allow burning. The result was excellent stands of both winter and summer annual legumes (Table 2). 3
Table 2. Dry matter yield of winter or summer legumes seeded with a
Zip(R) sod seeder in bahiagrass treated with various herbicides.
Ona ARC. 1977-78.
Canopy control
Before After Herbicide Legume yield
seeding seeding treatment Winter annualt Summer annual,
------------kg/ha-------yes no Paraquat (R) + burn 6640 2970 3
no yes Dowpon(R) M 3840 2810
no no no herbicide 1310 260 I
Red and white clover.
t Aeschynomene, hairy indigo, alyce clover. 3
Divide kg/ha by 1.121 to get lb/A.
Burning 12 to 14 cm tall (4.7 to 5.5 inch) bahiagrass resulted in temperatures i that reached 83 C (182 F) at the soil surface. The value of this heat is demonstrated in the control of insects and other pests that eat legume seedlings. At the Ona ARC a small land snail (Polygyra cereolus) has been found to be responsible for decimating stands of sod-seeded clovers. Burning resulted in 98% mortality of this pest, resulting in successful legume establishment.
I
U




89
Controlling competition after seeding.
Control of sod growth after legume emergence can be accomplished with grazing or herbicides. Herbicides are valuable for controlling competition after seeding because they can stop grass growth. When herbicides were applied
to 7 to 10 cm tall (2.8 to 4 inch) bahiagrass in late June, better yields of summer legumes were obtained as compared to untreated grass (Table 3). Successful stands of legumes resulted when canopy cover was slight at seeding and sod control was employed during legume development.
Table 3. Dry matter yield of summer legumes sod-seeded in bahiagrass
treated with various herbicides. Ona ARC. 1977-78.
Legume yield*
Herbicide Sod control Aeschynomene Alyce clover Hairy indigo
-----------------kg/ha--------------Round-up Excellent 4950 5030 1900
Dowpon(R) Good 2920 4130 1380
Paraquat(R) Poor 100 970 140
No herbicide Poor 210 450 120
Divide. kg/ha by 1.121 to get lb/A.
Using herbicides to control competition after seeding winter legumes has questionable value. Delaying seeding date in south Florida until after November 15 usually assures that bahiagrass growth will be slowed by cool temperatures. When night temperatures fall below 15 C (59 F) bahiagrass growth almost stops. If competition at seeding time has been removed, little growth will develop after seeding. Hence,with winter annuals it is much nore important to remove competitionat seeding than to control competition after seeding.
To demonstrate this point, the canopy was removed at seeding by paraquat and burning, and the grass canopy regrew slowly, but was unchecked through the late fall and winter. (Table 2). Excellent yields were obtained from red and white clover (6640 kg/ha) in this burn treatment, but poorer yields (3840 kg/ha) resulted in a Dowpon M treatment where the grass canopy ;emained at seeding, but all new growth was stopped. Similar summer annual yields resulted with a burn vs Dowpon M treatment (2970 vs 2810 kg/ha) but yields produced from untreated grass were poor (260 kg/ha). Both types of competition control are necessary when sod seeding summer legumes in bahiagrass, but removing sod cover prior to seeding is most important for winter legumes.
Sod-seeding machines.
if a good job is done controlling grass competition and adequate fertility and water are supplied (for winter legumes), then the type of sod-seeding drill that you use makes little difference in the legume establishment. (Rye have used very simple, relatively inexpensive machines, such as the Zip




90
seeder; intermediately priced machines, such as the John Deere Powr-till(R) i
and Tye(R) seeder; or very expensive, sophisticated machines like the Bettison 3-D seeder and have had success with all of these. If the practices for successful establishment are followed, then machine preference is a personal and economic matter. As pointed out earlier, disking sod and broadcasting seed can result in good establishment. i
The following are steps recommended for establishing winter or summer annuals in bahiagrass in south Florida.
Winter annuals (alfalfa, red and white clover).
1. Limit the use of nitrogen on bahiagrass after September 15. Raise
the soil pH to 6.0 for clover and 6.5 for alfalfa.
2. Before seeding graze, remove as hay, or burn off all excess
bahiagrass leaving a maximum of 7.6 cm (3 inches). I
3. Inoculate seed with proper strain of fresh Rhizobium and seed
legumes after November 15 to take advantage of cool temperatures which limit bahiagrass growth. Waiting until November 15, also
increases the chances of rain from cold fronts.
4. Fertilize legumes at seeding with 340 to 450 kg/ha (300 to 400 lbs/A) i
of 0-10-20 and after the first cutting (about March 15) apply another
340 to 450 kg/ha of 0-10-20. Apply micronutrients if none were
applied in the past 4 years. I
5. Irrigate if necessary. Irrigation may be more important with disk
and broadcast methods of seeding than sod drill methods because
of poorer seed-to-soil contact with the former.
6. Bahiagrass growth may be grazed or mowed during legume establishment, provided seedlings are not clipped.
Summer annuals (aeschynomene, alyce clover, hairy indigo).
1. Limit the use of nitrogen fertilizer on bahiagrass after April 15.
Raise soil pH to 5.5 to 6.0.
2. Before seeding, graze, remove as hay, or burn (after desiccation with paraquat) all excess bahiagrass, leaving a maximum of 7.6 cm
(3 i I
3. If herbicides are used to control sod growth after seeding, best results will result if the chemicals are applied 2 to 3 weeks
before seeding so that sod-control is in effect. Dowpon M, especially I
if part of a smutgrass control program, is recommended at 2.5 kg/ha
active (3.0 lb/A).
4. Inoculate seed with proper strain of fresh Rhizobium and seed legumes i
after June 15 to increase the probability of favorable moisture
conditions. Seed naked aeschynomene (de-hulled), and for all legumes it is desirable to use seed rates that are 20 to 25% higher than used
I