Crop yield comparision and economic analysis for single-and double-crop systems

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Crop yield comparision and economic analysis for single-and double-crop systems
Series Title:
Research report (North Florida Research and Education Center (Quincy, Fla.))
Teare, I. D ( Iwan Dale ), 1931-
North Florida Research and Education Center (Quincy, Fla.)
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Quincy Fla
North Florida Experiment Station
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14 p. : ; 28 cm.


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Crop yields ( lcsh )
North Florida ( local )
City of Quincy ( local )
Corn ( jstor )
Soybeans ( jstor )
Wheat ( jstor )
bibliography ( marcgt )
non-fiction ( marcgt )


Includes bibliographical references (p. 14).
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Caption title.
Statement of Responsibility:
I.D. Teare ... et al.

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Crop Yield Comparisons and Economic Analysis
Single- and Double-crop Systems

I.D. Teare, D.L. Wright,
R.D. Barnett, D.W. Gorbet, T.D. Hewitt

Central Science

FEB 13 1990

University of Florida

North Florida Research and Education Center, Quincy, FL 32351 and
Marianna FL 32446 (Institute of Food and Agricultural Sciences,
Univ. of Fla., Gainesville, FL 32611). Research Report NF-90-6.


North Florida has been traditional an area of agronomic crop

production. While there have been short cycles in acreage

devoted to other specific crops, the majority of the acreage has

remained agronomic.

The low-energy-thrust program of the '70's speeded the

development of the no-till or minimum-till planting equipment and

technology that has been instrumental in reducing land prepara-

tion costs and increasing cash returns of both single- and

double-crop systems.

The most successful agronomic double-crop system in the

southeast has been fall planted wheat (primary-crop), harvested

between 24 May and 1 June, followed by a soybean crop (double-

crop) planted -around 12 June (Herzog et al., 1989, and Wright,

1984). There are presently two major problems associated with

the production and sale of soybean. The first is the low world

price of soybean. Soybean .prices for the last six years have

been: 1984\$6.20, 1985\$5.20, 1986\$4.90, 1987\$5.55, 1988\$7.50,

and 1989\(estimated)$6.00 (based on USDA Fla. Agric. Statistics

Service, Field Crops, 1222 Woodward Street, Orlando, FL 32803).

The. second is that nematodes numbers build-up under a soybean

crop (Whitty, 1988), not only affecting the soybean yield, but

the yield of following crops that are susceptible to nematodes

(especially root knot).

Nematode problems can be moderated using rotation crops with

low host suitability. Two crops with low host suitability for

nematodes are corn and sorghum, although host suitability varies

in relation to hybrid. Therefore a corn or sorghum crop in

rotation with a susceptible crop lowers the nematode numbers

available to feed upon the subsequent susceptible crops.

Sorghum has shown varying potential in double-cropping

(Sanford et al., 1986), but in Florida the use of sorghum as a

double-crop in relation to a primary-crop has not been reported.

The objective of this work was to compile information about

specific yields of crops that could be used with wheat in a

double-crop system or compared with other competitive single- or

double-crop systems in North Florida.

Materials and Methods

The research was conducted at the North Florida Research and

Education Center at Quincy, FL on a Norfolk sandy loam soil

(fine-loamy, -siliceous, thermic, Typic Paleudult) and/or

Marianna, FL on a Chipola loamy sand (loamy, siliceous, thermic

Arenic Paleudult).

The experimental design for all crops was a randomized

complete block with four replications.

WHEAT: Florida 302 and 303 were planted from 25 Nov to 10 Dec

from 1985 to 1988 at a planting rate of 1.5 to 2 bu/A. The

initial fertilization occurred one day prior to planting when 500

lb of 5-10-15 (N-P-K) was applied to the seedbed. Urea (46-0-0)

was applied according to fertilizer test from 22 Jan to 7 Feb

each year at approx. 50 lb N/A. All K was applied preplant.

Weeds were controlled according to species and number present in

relation to standard extension recommendations. Wheat yields

were corrected to 12% moisture.

SOYBEAN: Braxton soybean were planted 12 June in 6-row plots x

20-m with 0.76-m row spacing. Yield estimates were made by

harvesting 12-m of row from 2 rows. Plots were sprayed about 29

Sept with Asana 1.9 EC at 0.025 lb(AI)/A each year to control

stink bugs and about 1 Sept with Dimalin 25W at 0.5 oz (AI)/A

each year to control velvet bean caterpillar. Spray applications

were made at 36 psi and with 25 gal water/A. Soybean were not

fertilized. Soybean yields were corrected to 13% moisture.

CORN: Tropical corn: Pioneer hybrid brand X-304C (coded X304C)

was planted in 4-row plots in a moderate-energy-input system

defined as: 1. nitrogen fertilization at 120 lb N/A (20 lb/A

applied on the surface at planting and 100 lb/A side dressed when

the crop was 24 inches high in 1985 and changed to 12 inches high

for 1986, 1987-, 1988; and 2. no irrigation. X304C was planted

with a no-till planter in 24 foot rows with 30-inch spacing

between rows at a population density of 18,000 plants/A.

Tropical corn yields were corrected to 15.5% moisture.

Temperate corn: Asgrow hybrid brand 5509 (coded A5509) was

planted in 4-row plots in a moderate-energy-input system

(described above) in 1988 to compare with the high-energy-input

system recommended in the Southeast and known as the plow-layer-

management system defined as; 1. Fertilizer applied for maximum

corn yields according to soil test results up to the rates of

300-100-300 lb/A of N-P-K; 2. irrigation as scheduled by

tensiometers placed at 6 inch depth reached 0.02 MPa. A5509 was

planted with a no-till planter in a prepared seedbed in 24 foot

rows with 30-inch spacing between rows at a population density of

30,000 plants/A. Grain yields were harvested by plot combine

from 2 row trimmed to 20 feet. Two hundred and sixty lb N/A was

applied at fixed amounts according to the following schedule:

1. prior to planting, 50 lb N/A was applied as 1,000 lb 5-10-15;

2. at planting 10 lb N/A was applied on the surface as ammonium

polyphosphate (10-34-0); 3. About 21 April when the corn was

24 inches tall, 120 Ib N/A was banded near the row; 4. on 13

May 100 lb N/A was injected through the overhead sprinkler with

boron. Total N applied was 280 lb N/A. Temperate corn yields

were corrected to 15.5% moisture.

SORGHUM: Planting date, hybrid, and previous crop is shown for

sorghum in table 4. Nitrogen was applied at 100 lb/A about 20

days after planting. Four row plots were 48 feet long with rows

30 inches apart. Sorghum was planted with a no-till planter and

subsoiler (set at 12 inch depth). Plant density was approxi-

.mately 45,000 sorghum plants/A. Grain yield was determined on 10

foot sections of center row. Late planted sorghum required irri-

gation which was scheduled as in corn. Late planted sorghum also

had bird problems. Bird feeders with corn soaked in Avinol and

broadcast sprayed Azodrin 5 (2 pt/A) were used for control with

varing degrees of success. Midge was a problem in sorghum in

1982 and was broadcast sprayed 21 July with a hiboy sprayer with

Sevin at 3 lb/A. Midge and webworm were problems in late Aug,

1983 but both were controlled with Lannate at 2 pt/A or Orthene

at 1 3/4 pt/A. Fall armyworm can also be a problem on sorghum

but did not reach economic threshholds requiring treatment during

the study. Weeds were controlled as necessary according to


extension recommendations. Sorghum yields were corrected to 12%


Results and Discussion

Wheat in North Florida in the past was used as a winter

grazing crop, but as cattle numbers dwindled in the 70's, wheat

acreage also dwindled to 17,000 acres in 1978. In 1979, the

Florida reporting service ceased reporting wheat acreage planted

or wheat yields for the state of Florida. With the release of

Florida 301 in 1980, wheat acreages increased to a high of

160,000 acres in 1985 and has averaged about 100,000 each year

since. By 1984, Florida 301 was grown on more than 1 million

acres, making it the most popular soft red wheat winter wheat in

the South. Florida 302 was released in 1984 and has become the

most popular wheat grown from East Texas To Virginia and Pennsyl-

vania. In 1988, nearly 3 million acres of Florida 302 were

grown. As successful as Florida 302 is, it has a problem in the

double-crop system, since it matures about 1 June or 10 days

to 1 week later than Florida 301. At present Florida 302 is the

predominant wheat cultivar grown in the southeast in double-crop

systems. However a new cultivar, Florida 303 was selected and

released in 1988 for its desirable trait of high yield coupled

with early maturity (reaching maturity about 12 to 16 May) and

resistance to leaf rust and powdery mildew (Barnett, et al.,

1988). This makes it a more ideal wheat cultivar for use in a

double-cropping system because earlier maturity provides a wider

window for the early planting of soybean, tropical corn, or

sorghum (using 15 June as the cut-off date, after which the fall


armyworm can cause devastating outbreaks on tropical corn).

Wheat yields are shown in Table 1.

Table 1. Wheat Yields1 (bu/A) for Florida 301, 302, and 303
during 1985 to 1988 at Quincy FL.
Year Florida 301 Florida 302 Florida 303


1985 56 45 49
1986 60 48 60
19872 57 55 64
19873 43 65 62
19884 65 63 70
19885 58 62 70

Mean 56 56 62

1 Agronomists of IFAS, Univ. of Fla., Florida Field and Forage
Crop Variety Reports: AY86-10, AY87-2, AY88-02, AY89-07.
2 State Variety Test
Uniform Southern Test
4 Early Planted State Test (12-1-87)
s Late Planted State Test (12-9-87)

Soybean is an ideal low-energy-input crop for double-cropping

after wheat in the south. Florida 302 wheat is harvested from 24

May to 10 June each year in North Florida. Soybean growing re-

quirements fit the environment at that time. Herzog (1988) has

shown that Braxton yields the best when planted 8 June. Soybean

has very few disease pests, but many insect pests, ie., velvet-

bean caterpillar, soybean looper, and stink bug. Therefore,

soybean fields must be scouted on a regular basis during the

growing season to monitor pests and determine when spray applica-

tion is necessary. Soybean yields in relation years and early

June planting date are shown in Table 2.

Table 2. Soybean (Braxton) yields' [early planted (15 May),
without nematodes] in relation to years, 1983 through 1988.
Year Mean

1983 42
1984 42
1985 35
1986 41
1987 55
1988 42

Mean 43

1 Agronomists of IFAS, Univ. of Fla., Florida Field and Forage
Crop Variety Reports: AY84-9, AY85-10, AY86-10, AY87-2,
AY88-01, AY89-07.

Table 3. Nematodes in relation to Braxton soybean yieldl for
specific locations2 during 1981 to 1988.



Javanese Soybean cyst Soybean cyst Southern
root-knot race 3 race 4 root-knot

Meliodogyne Heterodera Heterodera Meliodgyne
javanica glycines glycines incognita

bu/A (Location)

34 Jay
29 Jay
27 SA
5 SA

16 SA

16 SA

6 Jay
5 Jay

9 Jay

5 LO
19 LO

12 LO

2 LO

7 LO

32 Jay

30 Jay
30 Jay

24 Jay

19 JC
20 Jay

7 JC

45 Jay

42 Jay
42 Jay
27 Jay
38 Jay
24 Jay
21 Jay
17 MC
20 MC
26 Jay
32 Jay

1 Agronomists of IFAS, Univ. of Fla., Florida Field and Forage
Crop Variety Reports: AY82-7, AY83-13, AY84-9, AY85-10,
AY86-10, AY87-2, AY88-02.
2 LO=Live Oak, SA=Santa Rosa, JC=Jackson County, MC=Madison









Maize or corn [Zea Mays (L.)] has been bred along two dis-

tinct lines. The most well known in the US are the hybrids bred

for high yield and high-energy-inputs (ie., high fertility,

irrigation, weed control, disease and insect control) that we

will designate as temperate corn. Wright, et al.(1987) have

shown the effect of planting date on temperate corn when it is

grown in a singlecrop system from early Feb to early May. We've

chosen Asgrow brand hybrid 5509 from this group. Year, planting

dates, grain yields and problems are shown in Table 3.

Table 4. Temperate corn (A5509) in relation to sowing date, har-
vest date, water use (ppt/irr), grain yield and some problems
when grown in a high-energy-input system and low-energy-input

Year Sowing Harvest Applied Water ppt/ Grain Problems
Date Date N Mgt. irr yield'
(Ib/A) (in.) (bu/A)


1985 28 Mar 5 Aug 260 irr. 22/5 196
1986 24 Mar 4 Aug 260 irr. 11/10 244
1987 16 Mar 10 Aug 260 irr. 22/6 175
1988 24 Mar 5 Aug 260 irr. 15/12 182


1987 16 Mar 10 Aug 260 dryland 22/0 48
1988 15 June 27 Oct 120 dryland 23/0 29 earworm and
rice weevil

Tropical corn has an interesting history. Plant breeding

knowledge was exported during the 50's and 60's (Abington, 1975)

to third world countries, hybrid seed company's picked up the

idea in the 70's and 80's and developed tropical hybrids for

third world countries that have caught the interest of farmers

and scientists in subtropical parts'of the US. Tropical hybrids

are now being imported back to the original source of knowledge.

The desirable characteristics of tropical corn are the moderate

yields that can be attained with relatively small amounts of

nitrogen fertilizer, reduced insect, disease, and weed problems,

and reduced grain storage problems in the field and granary. The

most dependable yielder that we've found in this group (recog-

nizing that we haven't extensively tested all tropical hyrids) is

Pioneer brand hybrid X-304C. Years, sowing date, harvest date,

grain yield, and some problems observed in tropical corn are

shown in Table 5.

Table 5. Tropical corn in relation year, sowing date, harvest
date, applied N, water use (water mgt., ppt/irr), grain yield,
and some problems in a low-energy-input system.

Year Sowing Harvest Applied Water ppt/ Grain Problems
Date Date N Mgt. irr Yield'
(Ib/A) (in.) (bu/A)

1985 13 June 23 Oct 120 Dryland 16/0 64 Sidedressed
late, lodging
1986 16 June 21 Oct 120 Dryland 25/0 97
1987 24 June 27 Oct 120 Dryland 15/0 96
1988 15 June 27 Oct 120 Dryland 23/0 88

1 Yields with same letter are not significantly different at the
1 % level of probability.

Planting sorghum in late May through late July results in

lower yields, because sorghum is likely to be damaged by midge,

webworm, and anthracnose during this period (Table 5). Although,

late July sorghum plantings have been been grown successfully, it

is best utilized in double-crop systems following temperate corn

or wheat (Wright and Gorbet, 1985) in the southeast. Sorghum

planted in late July matures around 20 Nov, and will probably

need supplemental irrigation during the predictable drought in

the Southeast in Sept, Oct and Nov This and bird, insect, and

disease problems encountered with late planting can move sorghum

into the high-energy-input category.

Table 6. Sorghum (Funk G 522DR) yield in relation to early plant-
ing (around 15 April) and late planting (around 15 June) in bu/A
from 1983 through 1988.

Year Early Planting Late Planting
1983 92 48
1984 80 44
1985 90 24
1986 94 46
1987 88 48

Mean 89 40

1 Agronomistis of IFAS, Univ. of Fla., Florida Field and Forage
Crop Variety Reports: AY84-9, AY85-10, AY86-10, AY87-2,
AY88-02, AY89-07.

Table 7. Sorghum yields in relation to date of planting (DOP),
harvest date (HD), irrigation (I), and problems (BD=bird damage,
M=midge) for decision-making in single- or double-cropping

Funks Funks Funks Funks Funks Funks
G 522DR G 522DR G 522DR G 522DR G 522DR G 522DR

DOP 4-14-81 5-18-81 6-5-81 7-13-81 7-28-81 8-11-81

Rep bu/A

I 102 68 43 112 102 71
II 103 64 49 106 104 73
III 105 72 41 103 108 78
IV 104 72 43 107 105 74

Mean 104 69 44 107 106 74


BD 8/27 9/28 10/8 10/8
M 7/21
I none none none Irr Irr Irr
HD 7/28 8/18 9/14 11/6 11/23 11/25

Yield, cost, price, and net return for single- and double-

crops are shown in Table 8. To calculate returns from double-

cropping, add the net returns of the two crops selected.

Double-cropping reduces production costs of the following-crop

because it can utilize residual fertility from the previous crop.

Table 8. Cost analysis of some agronomic crops grown in single- or double-crop systems in

Variable cost/acre

Fixed cost/acre

Total cost/acre

Yield (bu/A)17

Total cost/bu

Mean price ($/bu)

Net return/bu

Net return/acre

Wheat Soybean1-/


82 90

30 30

112 120

62 43

1.81 2.73

2.91 5.87

1.10 3.14

68.20 138.16

Tropical Corn


Double Single Double1/ Doublel/

120 140 125 190

30 40 30 110

150 180 155 300

94 94 40 90

1.60 1.92 3.88 3.33

2.48 2.48 2.23 2.23

0.88 0.56 -1.65 -1.10

82.72 52.64 -66.00 -99.00

















the Southeast.

Temperate Corn

Single5/ Singlei/

240 125

110 30

350 155

200 30

1.75 5.17

2.48 2.48

-0.73 -2.69

22.75 -83.23 -199.27 -80.70

L/Nematode free yield trials at Quincy, FL.

2/Double-cropped after wheat for grain, dryland.

1/Double-cropped after corn for grain with irrigation.

!/Double-cropped after wheat for grain, dryland.


6/Single-cropped dryland spring grown during dry year.

!/Single-cropped dryland spring grown during wet year.

I/Yields based upon research in north Florida.













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Our thanks to E. Brown, Agric. Tech. IV, and B.T. Kidd, Biol.
Sci. II: North Fla. Res. and Educ. Ctr., Univ. of Fla.,
Quincy,FL; for data collection, computer processing, and data
Abington, J.B. 1975. Development of a maize breeding program in
Zambia. I. Evaluation of introduced material and formation of
Zambia Composite Z. Trop. Agric. (Trinidad) 51:31-38.

Barnett, R.D., P.L. Pfahler, H.H. Luke, and A.R. Zimet. 1988.
Florida 303 a new early maturing wheat for North Florida.
Univ. of Fla., North Fla. Res. and Educ. Ctr., Quincy FL. Res.
Rep. NF-88-5.

Herzog, D.C., D.L. Wright, F.M. Shokes, and I.D. Teare. 1988.
Planting date influence on yield, height, and harvest date of
selected soybean cultivars. Univ. of Fla., North Fla. Res. and
Educ. Ctr., Quincy FL. Res. Rep. NF-88-9.

Jones, D.W., R.A. Dunh, D.H. Teem, F.A. Johnson, and T.C.
Skinner. 1982. Field corn Production Guide. Fla. Coop. Ext.
Ser., Inst. of Food and Agric. Sci. Univ. of Fla., Gainesville.
Cirular 144-F.

Teare. I.D., D.L. Wright, and D.J. Zimet. 1989. Four years
experience with tropical corn in a doublecrop system. Univ. of
Fla.. North Fla Res. and Educ. Ctr., Quincy FL Res. Rep.

.Whitty, B. 1988. History of crop production and rotations used
in North Florida. Univ. of Fla., Dept of Agron., In-service
Training Program "Utilizing crop rotations for profitable
agronomic enterprises", 18-19 Nov. at Quincy FL.

Whitty, E.B. 1974. Soybean recommendations. Fla. Coop. Ext.
Ser. Agronomy Facts 50: 1-2.

Wright, D.L., 1984. Considerations for Multicropping and No-till
Soybeans. Univ of Fla., North Fla. Res. and Educ. Ctr., Quincy
FL. Agron Mimeo.

Wright, D.L., and D.W. Gorbet. 1985. Grain sorghum production
guide. Fla. Coop. Ext. Ser., Inst. of food and Agric. Sci. Univ
of Fla. Gainesville, FL. Circular 346-B.

Wright, D.L., and F.M. Rhoads. 1981. High corn yields with
intensive management. Fla. Coop. Ext. Ser., Univ. of Fla.
Agronomy Facts 116:1-7.

Wright, D.L., F.M. Shokes, M.C. Lutrick, and W.B. Tappin. 1982.
Principle of wheat and no-till soybean production. Fla. Coop.
Ext. Ser., Inst. of Food and Agric. Sci., Univ. of Fla. Circular

Wright, D.L., I.D. Teare, and B.T.Kidd. 1987. Ontogeny of maize
in relation to sequential cropping. Trop.