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Group Title: Bulletin University of Florida. Agricultural Experiment Station
Title: Effect of rotations, fertilizers, lime and green manure crops on crop yields and on soil fertility
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Permanent Link: http://ufdc.ufl.edu/UF00027033/00001
 Material Information
Title: Effect of rotations, fertilizers, lime and green manure crops on crop yields and on soil fertility
Series Title: Bulletin University of Florida. Agricultural Experiment Station
Physical Description: 32 p. : ill. ; 23 cm.
Language: English
Creator: Thompson, L. G ( Leonard Garnett ), 1903-
Robertson, W. K ( William Kendrick )
Publisher: University of Florida Agricultural Experiment Station
Place of Publication: Gainesville Fla
Publication Date: 1953
Copyright Date: 1953
 Subjects
Subject: Crop yields -- Florida   ( lcsh )
Soil fertility -- Florida   ( lcsh )
Crop rotation -- Florida   ( lcsh )
Genre: government publication (state, provincial, terriorial, dependent)   ( marcgt )
bibliography   ( marcgt )
non-fiction   ( marcgt )
 Notes
Bibliography: Includes bibliographical references (p. 32).
Statement of Responsibility: L.G. Thompson, Jr. and W.K. Robertson.
General Note: Cover title.
 Record Information
Bibliographic ID: UF00027033
Volume ID: VID00001
Source Institution: University of Florida
Holding Location: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: ltuf - AEN6698
oclc - 18270581
alephbibnum - 000926039

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Full Text


Bulletin 522 August 1953


UNIVERSITY OF FLORIDA
AGRICULTURAL EXPERIMENT STATIONS
WILLARD M. FIFIELD, Director
GAINESVILLE, FLORIDA







Effect of Rotations, Fertilizers, Lime and

Green Manure Crops on Crop Yields

and on Soil Fertility


L. G. THOMPSON, JR., and W. K. ROBERTSON



Fig. 1.-Corn and peanuts grown in rotation.










J. .
iAL-












BOARD OF CONTROL EDITORIAL
J. Francis Cooper, M.S.A., Editor 3
Hollis Rinehart, Chairman, Miami Clyde Beale, A.B.J., Associate Editors
J. Lee Ballard, St. Petersburg J. N. Joiner, B.S.A., Assistant Editors
Fred H. Kent, Jacksonville William G. Mitchell, A.B.J., Assistant Editor
Wm. H. Dial, Orlando
Mrs. Alfred I. duPont, Jacksonville ENTOMOLOGY
George W. English, Jr., Ft. Lauderdale A. N. Tissot, Ph.D.,Entomologist
W. Glenn Miller, Monticello A.. Tissot, Ph.D., Entomologist
W. F. Powers, Secretary, Tallahassee L. C. Kuitert, Ph.D., Associate
H. E. Bratley, M.S.A., Assistant
EXECUTIVE STAFF F. A. Robinson, M.S., Asst. Apiculturist
R. E. Waites, Ph.D., Asst. Entomologist
J. Hillis Miller, Ph.D., President
J. Wayne Reitz, Ph.D., Provost for Agr.3 HOME ECONOMICS
Willard M. Fifield, M.S., Director Ouida D Abbott Ph.D. Home Econ.1
J. R. Beckenbach, Ph.D., Asso. Director ia D.FenA o, Ph.D., och e Econ
L. O. Gratz, Ph.D., Assistant Director R. B French, Ph.D., Biochemist
Rogers L. Bartley, B.S., Admin. Mgr.3 HORTICULTURE
Geo. R. Freeman, B.S., Farm Superintendent HO ULU
G. H. Blackmon, M.S.A., Horticulturist1
F. S. Jamison, Ph.D., Horticulturist a
MAIN STATION, GAINESVILLE Albert P. Lorz, Ph.D., Horticulturist
R. K. Showalter, M.S., Asso. Hort.
R. A. Dennison, Ph.D., Asso. Hort.
AGRICULTURAL ECONOMICS R. H. Sharpe, M.S., Asso. Horticulturist
H. G. Hamilton, Ph.D., Agr. Economist V. F. Nettles, Ph.D., Asso. Horticulturist
R. E. L. Greene, Ph.D., Agr. Economist3 F. S. Lagasse, Ph.D., Horticulturist
M. A. Brooker, Ph.D., Agr. Economist R. D. Dickey, M.S.A., Asso. Hort.
Zach Savage, M.B.A., Associate L. H. Halsey, M.S.A., Asst. Hort.
A. H. Spureck, M..A Agr.sso economist C.B. Hall, Ph.D., Asst. Horticulturist
D. E. Alleger, M.S., Associate Austin Griffiths, Jr., B.S., Asst. Hort.
D. Allegerooke, M.S.., Associate S. E. McFadden, Jr., Ph.D., Asst. Hort.
M. L. Godwin, Ph.D., Associate3 C. H. VanMiddelem, Ph.D., Asst. Biochemist
. K. McPherson, M.S., Economist3 Buford D. Thompson, M.S.A., Asst. Hort.
Eric Thor, M.S., Asso. Agr. Economist3 M. W. Hoover, M.S.A., Asst. Hort.
Cecil N. Smith, M.A., Asso. Agr. Economist LIBRARY
Levi A. Powell, Sr., M.S.A., Assistant
Orlando, Florida (Cooperative USDA) Ida Keeling Cresap, Librarian
G. Norman Rose, B.S., Asso. Agri. Economist
J. C. Townsend, Jr., B.S.A., Agricultural PLANT PATHOLOGY
Statistician 2
J. B. Owens, B.S.A., Agr. Statistician W. B. Tisdale, Ph.D., Plant Pathologist 3
Phares Decker, Ph.D., Plant Pathologist
AGRICULTURAL ENGINEERING Erdman West, M.S., Botanist & Mycologist
Robert W. Earhart, Ph.D., Plant Path.S
Frazier Rogers, M.S.A., Agr. Engineers Howard N. Miller, Ph.D., Asso. Plant Path.
J. M. Myers, M.S.A., Asso. Agr. Engineer Lillian E. Arnold, M.S., Asso. Botanist
J. S. Norton, M.S., Asst. Agr. Engineer C. W. Anderson, Ph.D., Asst. Plant Path.
AGRONOMY POULTRY HUSBANDRY
Fred H. Hull, Ph.D., Agronomist 1 N. R. Mehrhof, M.Agr., Poultry Husb.1 3
G. B. Killinger, Ph.D., Agronomist J. C. Driggers, Ph.D., Asso. Poultry Husb.3
H. C. Harris, Ph.D., Agronomist
R. W. Bledsoe, Ph.D., Agronomist SOILS
W. A. Carver, Ph.D., Agronomist
Fred A. Clark, M.S., Associate 2 F. B. Smith, Ph.D., Microbiologist1 3
E. S. Horner, Ph.D., Assistant Gaylord M. Volk, Ph.D., Soils Chemist
A. T. Wallace, Ph.D., Assistant J. R. Neller, Ph.D., Soils Chemist
U. E. McCloud, Ph.D., Assistant 3 Nathan Gammon, Jr., Ph.D., Soils Chemist
G. C. Nutter, Ph.D., Asst. Agronomist Ralph G. Leighty, B.S., Asst. Soil Surveyor 2
G. D. Thornton, Ph.D., Microbiologist
ANIMAL HUSBANDRY AND NUTRITION C. F. Eno, Ph.D., Asst. Soils Microbiologist
T. J. Cunha, Ph.D., Animal Husbandman a3 H. W. Winsor, B.S.A., Assistant Chemist
G. K. Davis, Ph.D., Animal Nutritionist s R. E. Caldwell, M..A., Asst. Chemist u
R. L. Shirley, Ph.D., Biochemist V.W. Carlisle, B.S., Asst. Soil Surveyor
A. M. Pearson, Ph.D., Asso. An. Husb.s J. H. Walker, M.B.A., Asst. Soil Surveyor
John P. Feaster, Ph.D., Asst. An. Nutri William K. Robertson, Ph.D., Asst. Chemist
H. D. Wallace, Ph.D., Asst. An. Husb.3 0. E. Cruz, B.S.A., Asst. Soil Surveyor
M. Koger, Ph.D., An. Iusbandman 3 W. G. Blue, Ph.D., Asst. Biochemist
J. F. Hentges, Jr., Ph.D., Asst. An. Hus. J. G. A. Fiskel, Ph.D., Asst. Biochemist
L. R. HArrington, Ph.D., Asst. An. Hush. L.C. Hammond, Ph.D., Asst. Soil Physicist
H. L. Breland, Ph.D., Asst. Soils Chem.
DAIRY SCIENCE
DAIRY SCIENCE VETERINARY SCIENCE
E. L. Fouts, Ph.D., Dairy Technologist '3
R. B. Becker, Ph.D., Dairy Husbandman 3 D. A. Sanders, D.V.M., Veterinarian's
S. P. Marshall, Ph.D., Asso. Dairy Husb.3 M. W. Emmel, D.V.M., Veterinarian s
W. A. Krienke, M.S., Asso. Dairy Tech.3 C. F. Simpson, D.V.M., Asso. Veterinarian
P. T. Dix Arnold, M.S.A., Asso. Dairy Husb. 3 L. E. Swanson, D.V.M., Parasitologist
Leon Mull, Ph.D., Asso. Dairy Tech.3 W. R. Dennis, D.V.M., Asst. Parasitologist
H. H. Wilkowske, Ph.D., Asst. Dairy Tech.3 E. W. Swarthout, D.V.M., Asso. Poultry
James M. Wing, Ph.D., Asst. Dairy Husb. Pathologist (Dade City)











BRANCH STATIONS F. T. Boyd, Ph.D., Asso. Agronomist
M. G. Hamilton, Ph.D., Asst. Horticulturist
NORTH FLORIDA STATION, QUINCY
W. C. Rhoades, Jr., M.S., Entomologist in SUB-TROPICAL STATION, HOMESTEAD
Charge Geo. D. Ruehle, Ph.D., Vice-Dir. in Charge
R. R. Kincaid, Ph.D., Plant Pathologist D. 0. Wolfenbarger, Ph.D., Entomologist
L. G. Thompson, Jr., Ph.D., Soils Chemist Francis B. Lincoln, Ph.D., Horticulturist
W. IH. Chapman, M.S., Agronomist Robert A. Conover, Ph.D., Plant Path.
Frank S. Baker, Jr., B.S., Asst. An. Hush. John L. Malcolm, Ph.D., Asso. Soils Chemist
Frank E. Guthrie, Ph.D., Asst. Entomologist R. W. Harkness, Ph.I., Asst. Chemist
Mobile Unit, Monticello Bruce Ledin, Ph.D., Asst. Hort.
Mobile Unit, Montiello J. C. Noonan, M.S., Asst. Hort.
R. W. Wallace, B.S., Associate Agronomist M. H. Gallatin, B.S., Soil Conservationist2
Mobile Unit, Marianna
R. W. Lipscomb, M.S., Associate Agronomist WEST CENTRAL FLORIDA STATION,
BROOKSVILLE
Mobile Unit, Pensacola
R. L. Smith, M.S., Associate Agronomist Marian W. Hazen, M.S., Animal usband-
man in Charge 2
Mobile Unit, Chipley
J. B. White, B.S.A., Associate Agronomist RANGE CATTLE STATION, ONA
CITRUS STATION, LAKE ALFRED W. G. Kirk, Ph.D., Vice-Director in Charge
CITRUS STATION, LAKE ALFRED E. M Hodges, Ph.D., Agronomist
A. F. Camp, Ph.D., Vice-Director in Charge D. W. Jones, M.S., Asst. Soil Technologist
W. L. Thompson, B.S., Entomologist
R. F. Suit, Ph.D., Plant Pathologist CENTRAL FLORIDA STATION, SANFORD
E. P. Ducharme, Ph.D., Asso. Plant Path.
C. R. Stearns, Jr., B.S.A., Asso. Chemist R. W. Ruprecht, Ph.D., Vice-Dir. in Charge
J. W. Sites, Ph.D., Horticulturist J. W. Wilson, SeD., Entomologist
H. 0. Sterling, B.S., Asst. Horticulturist P. J. Westgate, Ph.D., Asso. Hort.
H. J. Reitz, Ph.D., Horticulturist Ben F. Whitner, Jr., B.S.A., Asst. Hort.
Francine Fisher, M.S., Asst. Plant Path. Gee. Swank, Jr., Ph.D., Asst. Plant Path.
I. W. Wander, Ph.D., Soils Chemist
J. W. Kesterson, M.S., Asso. Chemist WEST FLORIDA STATION, JAY
R. Hendrickson, B.S., Asst. Chemist
Ivan Stewart, Ph.D., Asst. Biochemist C. E. Hutton, Ph.D., Vice-Director in Charge
II. S. Prosser, Jr., B.S., Asst. Engineer H. W. Lundy, B.S.A., Associate Agronomist
R. W. Olsen, B.S., Biochemist
F. W .Wenzel, Jr., Ph.D., Chemist SUWANNEE VALLEY STATION,
Alvin H. Rouse, M.S., Asso. Chemist LIVE OAK
H. W. Ford, Ph.D., Asst. Horticulturist
L. C. Knorr, Ph.D., Asso. Histologist' G. E. Ritchey, M.S., Agronomist in Charge
R. M. Pratt, Ph.D., Asso. Ent.-Pathologist
W. A. Simanton, Ph.D., Entomologist GULF COAST STATION, BRADENTON
E. J. Deszyck, Ph.D., Asso. Horticulturist
C. I. Leonard, Ph.D., Asso. Horticulturist E. L. Spencer, Ph.D., Soils Chemist in Charge
W. T. Long, M.S., Asst. Horticulturist E. G. Kelsheimer, Ph.D., Entomologist
M. H. Muma, Ph.D.. Asso. Entomologist David G. A. Kelbert, Asso. Horticulturist
F. J. Reynolds, Ph.D., Asso. Hort. Robert O. Magie, Ph.D., Plant Pathologist
W. F. Spencer, Ph.D., Asst. Chem. J. M. Walter, Ph.D., Plant Pathologist
R. B. Johnson, Ph.D., Asst. Entomologist S. S. Woltz, Ph.D., Asst. Horticulturist
W. F. Newhall, Ph.D., Asst. Entomologist Donald S. Burgis, M.S.A., Asst. Hort.
W. F. Grierson-Jackson, Ph.D., Asst. Chem. C. M. Geraldson, Ph.D., Asst. Horticulturist
Roger Patrick, Ph.D., Bacteriologist
Marion F. Oberbacher, Ph.D., Asst. Plant FIELD LABORATORIES
Physiologist FIELD LABORATORIES
Evert J. Elvin, B.S., Asst. Horticulturist
R. C. J. Koo, Ph.D., Asst. Biochemist Watermelon, Grape, Pasture--Leesburg
J. R. Kuykendall, Ph.D., Asst. Horticulturist J. M. Crall, Ph.D., Associate Plant Path-
ologist Acting in Charge
EVERGLADES STATION, BELLE GLADE C. C. Helms, Jr., B.S., Asst. Agronomist
L. H. Stover, Assistant in Horticulture
W. T. Forsee, Jr., Ph.D., Chemist in Charge Strt
R. V. Allison, Ph.D., Fiber Technologist Strawberry-Plant City
Thomas Bregger, Ph.D., Physiologist A. N. Brooks, Ph.D., Plant Pathologist
J. W. Randolph, M.S., Agricultural Engr.
R. W. Kidder, M.S., Asso. Animal Husb. Vegetables--Hastings
C. C. Seale, Associate Agronomist A. H. Eddins, Ph.D., Plant Path. in Charge
N. C. Hayslip, B.S.A. Asso. Entomologist E. N. McCubbin, Ph.D., Horticulturist
E. A. Wolf, M.S., Asst. Horticulturist T. M. Dobrovsky, Ph.D., Asst. Entomologist
W. H. Thames, M.S., Asst. Entomologist
W. G. Genung, M.S., Asst. Entomologist Pecans--Monticello
Frank V. Stevenson, M.S., Asso. Plant Path. A. M. Phillips, B.S., Asso. Entomologist2
Robert J. Allen, Ph.D., Asst. Agronomist John R. Large, M.S., Asso. Plant Path.
V. E. Green, Ph.D., Asst. Agronomist Frost Foreastin Lakeland
J. F. Darby, Ph.D., Asst. Plant Path. Frost Forecasting-Lakeland
V. L. Guzman, Ph.D., Asst. Short. Warren O. Johnson, B.S., Meteorologist in
J. C. Stephens, B.S., Drainage Engineer Charge 2
A. E. Kretschmer, Jr., Ph.D., Asst. Soils
Chem. 1 Head of Department
Charles T. Ozaki, Ph.D., Asst. Chemist 2 In cooperation with U. S.
Thomas L. Meade, Ph.D., Asst. An. Nutri. 3 Cooperative, other divisions, U. of F.
I. S. Harrison, M.S., Asst. Agri. Engr. 4 On leave














CONTENTS
PAGE

INTRODUCTION ................ . .............. .. ..... 5
EXPERIMENTAL PROCEDURE .......---...--..--. ---- .... ...... .............. ..... .5
ROTATION EXPERIMENT ----..... --..... ..........-- .--..-----.. .......---- ..-..- 6
Corn .......... .........-.......... ............................. ........ .... .... 9
Peanuts ............................ .....--- -....--... .-------...... ............ 9
Crotalaria and velvet beans ...........-.. .......--....--- ..--.-- ..-- ....... 12
Lupine --...------...-..-. -- ---------......-.-------.. ..----....- ... .. .....--- ... 12
Oats .........--.--.-... ..-- ....---... ..---...---....---......---.-........ 13
FERTILIZER EXPERIMENT ......... ---------.... .--------. ----- -----....-- ........ 13
Corn ......--- ..... ..--- ...- .. ..... ...........-......----------- ........ 13
Peanuts .-. ------- -- --........-.-.-..-.....-......- .....-.- ....-........--- .... 13
Crotalaria ...--- ..........-. .... ........ .........--. -- ----... ---. ..-.......... 16
Oats for green manure ......-.-- ...-- ..........-- .. ---------..--.......... ..... ...... 16
Lupine ...........--. --- ... --- --- ------ ------------..- --.--.--.... .--........ 16
Oats for grain --------.....-- -----.................. ----.-....-- 17
LIME EXPERIMENT .......... ....... ................ ........................ ........ 18
Corn ---....... ...........-- ------ -----------...... .... -..- .....-......-- .. ......--- ......... 18
Peanuts ...... .......----------- ..-------------. ..--.. ----.. ----... ..----- 18
Crotalaria ..............-..........---. ..... --- ....--------- .....-..--- ....- -----.......... 19
Oats for green manure ---... --............. -............ -- --- ..-...--- ..... 20
Lupine --...........--------- --- -------........ .. .......... ...... ...... 21
Oats for grain ------......--- ............-------------.... --......... 21
HARVESTING VERSUS HOGGING OFF PEANUTS ---...........--........................ 21
CHEMICAL STUDIES OF SOILS AND PLANTS ........----.......--- .................. 22
Peanut plots ...................- --. --. -- ---------- --... .... -......-- -..--..... 22
Corn plots .....-- ..----...... ..................----- .. --------....-- .......... 25
ORGANIC MATTER AND MOISTURE EQUIVALENT STUDIES .-............-- ............. 26
NEMATODE STUDIES .--.....-..-..-----..-..--.--. ..------....--.---..-- ........ 29
SUMMARY AND CONCLUSIONS ...........-----..---....-..- --... -... ........-- .... 30
ACKNOWLEDGMENTS -.....-..-------..-.....--...-..-- -........ ............. 32
LITERATURE CITED --.-........ ......--------------....------ ....- ......... 32









Effect of Rotations, Fertilizers, Lime and

Green Manure Crops on Crop Yields

and on Soil Fertility

L. G. THOMPSON, JR., and W. K. ROBERTSON 1

INTRODUCTION
Two crops-corn and peanuts-occupy a large percentage of
the cultivated land in northwest Florida. The acute shortage
of edible oil during the war and reconversion period resulted
in high prices for peanuts, and consequently a substantial in-
crease in acreage for harvest. To obtain this increase in acre-
age, many farmers planted peanuts on the same land year after
year. This management practice resulted in serious depletion
of organic matter and fertility of the soil. On such soils both
peanut and corn yields have shown progressive declines.
It is extremely important to determine the best system of
soil management for rebuilding this depleted soil and maintain-
ing fertility of all the crop land.
This investigation was conducted to determine the effect of
various rotations, fertilizers, lime and green manure crops on
the yield of peanuts, corn and oats, and on the fertility of the
soil.
EXPERIMENTAL PROCEDURE
A 40-acre field of virgin wiregrass soil, which consisted mostly
of Norfolk loamy fine sand, was surveyed into field plots and
blocks during the winter of 1946-1947. Rotation, fertilizer,
lime and "hogged-off" peanut experiments, each in randomized
blocks, replicated four times, were initiated in the spring of
1947. A soil sample was taken from each individual plot be-
fore any fertilizer or lime was applied. As the experiment pro-
gressed soil samples were taken from time to time to study the
changes brought about in the soil.
Red Rustproof No. 14 oats were planted the first three years
and Southland oats the last year of the test. Bitter blue lupine
and Crotalaria spectabilis Roth were planted for green manure
crops. Florida W-1 hybrid corn was planted the first two years
and Dixie 18 hybrid corn the last three years of the experiment.
1Soils Chemist, North Florida Station, and Assistant Chemist, Main
Station, respectively.








6 Florida Agricultural Experiment Stations

Dixie runner peanuts were used throughout the experiment. All
corn received 10 pounds of zinc sulphate per acre annually. Pea-
nuts in all experiments were dusted each season with 60 to 80
pounds of elemental sulfur-DDT mixture per acre.
The lupine, crotalaria and, in some of the cropping systems,
oats were turned under for green manure. Corn was harvested
and stalks turned under. Both peanuts and vines were removed
from the land.
For the years 1947 to 1950, inclusive, the peanuts were dug
when they were ready, so that the loss in the ground was small
and was not measured. In 1951, excessive rain rotted the pegs
and many peanuts were left in the ground. These nuts were
scratched out of the ground by hand, dried, weighed, and in-
cluded in the yields.
The fertilizer used in all experiments was made from Uramon
(42 percent N), superphosphate (18% P205), and muriate of
potash (60 percent K20).

ROTATION EXPERIMENT
The rotation experiment consisted of six continuous 2 crops,
three two-year rotations and two three-year rotations. A list
of continuous crops and rotations appears with the yield data
in Tables 1 and 2. Each crop in the two- and three-year rotations
was grown every year. This was accomplished by alternating
the two-year rotations between two series of plots and the
three-year rotations among three series of plots.
At planting time corn and oats for grain received 500 pounds
per acre of 2-10-8 fertilizer. Corn was top-dressed with 32
pounds per acre of nitrogen from Uramon and oats with 32
pounds from nitrate of soda. Oats turned under received annual
applications of 500 pounds of 2-10-8 per acre the first three
years and no fertilizer the last year. Native cover turned under
was not fertilized. Peanuts were fertilized with 400 pounds
of 2-10-4 per acre for the first three years and 500 pounds of
2-10-8 fertilizer the last two years of the test.
Bitter blue lupine and Crotalaria spectabilis received 300
pounds per acre of 0-14-10 the first three years, but no fertilizer
during the last two years. Plowing was done with a pick-up
disk harrow the last four years. During the first two years,
the direction of plowing was clockwise around each block; it
In this bulletin the term "continuous" crop refers to a crop replanted
on the same area in successive seasons.






TABLE 1.-YIELDS OF CORN IN THE ROTATION AND CONTINUOUS-CROP EXPERIMENT.

Corn-Bushels per Acre
Rotation or Continuous Crop Length C I I
S__ 1947 1948 1949 1950 1951 Average
Corn, crotalaria under, oats under .................... 1 year 47.9 42.1 74.4 79.0 63.9 61.4

Corn, crotalaria under ................ .......... 1 year 47.9 38.6 69.9 82.3 61.7 60.1

Corn, lupine under ........................................ 1 year 42.2 40.9 67.4 75.0 57.1 56.5

Corn, native cover under .......... ....................... 1 year 42.5 35.6 58.0 57.8 49.4 48.7

Peanuts, lupine under
Corn, native cover under ..................................... 2 years 42.7 48.7 72.4 84.0 61.7 61.9

Peanuts, lupine under
Corn and velvet beans interplanted .................. 2 years 37.6 45.2 69.2 75.1 59.0 57.2

Peanuts, lupine under
Corn, crotalaria under ..................................... 2 years 45.4 50.1 73.5 83.4 63.7 63.2

Peanuts, lupine under o
Corn, lupine under ................ ........................... 42.2 48.3 73.7 87.2 63.2 62.9
Corn, oats under ................................ ..... 3 years 43.3 44.0 68.6 81.8 68.8 61.3

Peanuts, lupine under
Corn, oats for grain
Crotalaria under, oats under .................. ......... 3 years 45.2 44.0 79.7 93.2 63.8 65.2

L. S. D (.05) ..... .... ...... .. ...... .... .............. 4.9 6.0 5.1 8.1 5.8
L. S. D. (.01) .. ............. ........................................ 6.7 8.1 6.9 10.9 7.9
Florida W-1 hybrid corn was planted the first two years and Dixie 18 hybrid corn the last three years.
-









00

TABLE 2.-YIELDS OF PEANUTS IN THE ROTATION AND CONTINUOUS-CROP EXPERIMENT.


Unshelled Peanuts Pounds per Acre
Rotation or Continuous Crop Length e
1947 1948 1949 1950 1951 Average

Peanuts, native cover under .........-.- -........... 1 year 1,904 1,474 818 1,365 2,010 1,514

Peanuts, lupine under .......-----..............-....-. 1 year 1,938 1,359 898 1,365 1,887 1,489

Peanuts, lupine under
Corn, native cover under ..-..---.... -......... 2 years 1,736 1,661 1,080 1,391 2,221 1,618

Peanuts, lupine under
Corn and velvet beans interplanted .--...-......-.. 2 years 1,889 1,671 994 1,361 2,412 1,665

Peanuts, lupine under
Corn, crotalaria under ............................ .... 2 years 1,806 1,695 1,065 1,688 2,343 1,719

Peanuts, lupine under
Corn, lupine under
Corn, oats under ..---... ------------............... ..... 3 years 1,965 1,802 1,048 1,444 2,197 1,691

Peanuts, lupine under
Corn, oats for grain
Crotalaria under, oats under ..-.......................... 3 years 1,924 1,734 1,022 1,539 2,309 1,706 q

L. S. D. (.05) ---........... ........... .................... . Not sig. 230 184 276 224
L. S. D. (.01) ......- .... ..-.... .-.......................... 316 253 Not sig. 307







Effect of Rotations and Fertilizers on Crop Yields 9

was counter-clockwise the last two years to minimize border
effect.
Corn.-Yields of corn in the rotation and continuous-crop
experiment are given in Table 1. In the second year there
was as much as seven bushels increase in the yield of corn
grown in rotation, but a decrease of one to nine bushels in the
yield of corn grown continuously. The yield of corn in the
third year was 22 to 34 bushels higher than in the second year,
largely because of more favorable weather and the use of a
higher yielding hybrid. Native cover made little growth, but
where good crops of lupine and crotalaria were turned under corn
yields were nine to 32 bushels higher. This was partly due to
extra fertilizer used on the cover crops.
In the fourth year there was a five- to thirteen-bushel increase
over the third year in the yield of corn in all instances except
where corn followed a poor growth of native cover. Corn yields
in the fifth year were eight to 29 bushels lower than in the
third and fourth years, largely because of a less favorable sea-
son. The residual effect of the good growth of green manure
crops in the first four years of the experiment produced an
eight- to 19-bushel increase over corn following native cover.
After the first year of the experiment the yield of corn was
higher in the rotation plots than in the continuous corn plots
following a good green manure crop. Yields were about the
same in the two- and three-year rotations. In the fourth year
the cover crops were not fertilized, yet the rotation corn yielded
24 to 35 bushels per acre more than continuous corn following
native cover, Fig. 2. The stand of corn was not reduced, but
velvet beans interplanted with corn reduced the corn yield three
to nine bushels. Velvet beans yielded 304 to 1,472 pounds of
dry shelled beans per acre (Table 3); consequently the total
yield of both crops was on the average much larger.
Peanuts.-Yields of peanuts in the rotation and continuous-
crop experiment are shown in Table 2. The yield of peanuts
in all plots decreased in the second and third years, but the
largest decrease was in the continuous peanut plots. The low
yield of peanuts in 1949 was partly caused by the wet weather
in August (Table 25). During the next two years the yields
increased.
For five years the yield of peanuts was 100 to 200 pounds
higher on the rotation than on the continuous peanut plots.
Yields were about the same in the two- and three-year rotations.









0


TABLE 3.-YIELDS OF CROTALARIA AND VELVET BEANS IN THE ROTATION AND CONTINUOUS-CROP EXPERIMENT.

Green Weight of Crotalaria-Pounds per Acre
Rotation or Continuous Crop Length ]
1947 1948 1949 1950 1951

Corn, crotalaria under
Oats under ........................................ ........ 1 year 13,605 23,631 10,661 5,565 1,459
Corn, crotalaria under ............................... ...... 1 year 12,720 22,347 10,041 2,527 1,187
Peanuts, lupine under
Corn, crotalaria under ...-........------ .. --......... ... 2 years 12,778 17,925 11,294 8,320 5,140
Peanuts, lupine under
Corn, oats for grain
Crotalaria under, oats under ........................... 3 years 22,601 34,253 27,977 11,707 6,643

L. S. D. (.05) ....--......-- ...--- ..- -....-....................... 1,622 2,979 2,779 3,347 4,122
L. S. D. (.01) ......................---- ...................... -....... 2,333 4,284 3,997 4,813 Not sig.

Dry Shelled Velvet Beans-Pounds per Acre
Length
1947 1948 1949 1950 1951

Peanuts, lupine under
Corn and velvet beans interplanted ............-.... 2 years 941 420 304 1,472 859








TABLE 4.-YIELDS OF LUPINE IN THE ROTATION AND CONTINUOUS-CROP EXPERIMENT.

Green Weight of Lupine-Pounds per Acre
Rotation or Continuous Crop Length I
1948 1949 1950 1951 1952 o

Peanuts, lupine under ................-------------....... 1 year 11,696 2,694 15,794 2,229

Corn, lupine under ....................................... .... .. 1 year 11,652 5,634 17,572 6,967
Peanuts, lupine under
Corn, native cover under .................................... 2 years 12,044 8,785 15,037 3,587

Peanuts, lupine under
Corn and velvet beans interplanted .................... 2 years 11,442 9,220 15,662 3,478

Peanuts, lupine under
Corn, crotalaria under ........................................... 2 years 11,609 9,199 14,856 2,578
Peanuts, lupine under
Corn, lupine under .................................................... 3 years 12,095 9,946 18,268 4,952 C
Corn, oats under ........................................... ........ 14,541 2,890 16,302 7,326 0

Peanuts, lupine under
Corn, oats for grain
Crotalaria under, oats under ................................ 3 years 10,157 10,179 18,979 8,371

L. S. D. (.05) ........................ .............................. 2,498 2,520 2,807 2,189
L. S. D. (.01) .............................. ...................... 3,398 3,429 3,820 2,778
A severe freeze in February completely killed the lupine.

I-A








12 Florida Agricultural Experiment Stations

The average yield of continuous peanuts with native cover was
slightly higher than continuous peanuts with lupine.
Where lupine followed peanuts each year plant nutrient defi-
ciencies and diseases killed many of the plants; this caused a very
low yield of lupine in the fifth year. Diseases common to both
crops, such as Rhizoctonia spp. and Sclerotium rolfsii Sacc., may
make it necessary to grow peanuts and lupines only once in a
three-year rotation instead of once in a two-year rotation. In
1952 lupine following peanuts in a two-year rotation made poor
growth because of diseases, while lupine following peanuts in a
three-year rotation made good growth (Table 4).
Crotalaria and Velvet Beans.-Yields of crotalaria and velvet
beans in the rotation and continuous-crop experiment are pre-
sented in Table 3. The highest yield of crotalaria was obtained
the second year, probably because of residual fertilizer from the
first two crops. Competition from native weeds, especially crab
grass, reduced the yield of crotalaria each year after the second.
The yield was very low in 1951.
Lupine.-Yields of lupine in the rotation and continuous-crop
experiment are shown in Table 4. Lupine made a fair growth
in the winter of 1947-1948. The next year the yield was lower
because of brown spot (Ceratophorium setosum Kirchn.).
In 1949 it was observed also that lupine following continuous
peanuts made the lowest yield because of diseases common to
both crops, such as Rhizoctonia spp. and Sclerotium rolfsii Sacc.

Fig. 2.-Left: Corn grown in a three-year rotation of peanuts, lupine
turned under, corn, oats for grain, crotalaria turned under, oats turned
under. Yield 93 bushels. Right: Corn grown successively for four years.
Yield 58 bushels.

















C- I, W.







Effect of Rotations and Fertilizers on Crop Yields 13

When lupine was grown only once in a two-year rotation the
increase in yield was highly significant. In the fifth year lu-
pine yielded higher following corn each year than in peanut rota-
tations, except where lupine and peanuts were each grown only
once in three years.
Oats.-Yields of oats in the rotation and continuous-crop ex-
periment are given in Table 5. Oats following crotalaria turned
under for green manure made higher green weight yields than
oats following corn, but the difference was significant only in
the first year. The green weight yield of oats in 1951 was so
low because of cold weather that it was not measured.

FERTILIZER EXPERIMENT
The fertilizer experiment was a randomized block designed
with four replications and three levels each of nitrogen (N),
phosphoric acid (PO.) and potash (KO2) applied to all crops
in a three-year rotation. The rotation used was as follows:
First year-peanuts, lupine under; second year-corn, oats for
grain; third year-crotalaria under, oats under. The fertilizer
applied to each crop appears with the yield data in Tables 6
to 11. All six crops were grown each year in each replication.
This was accomplished by alternating the six crops among three
sets of plots each year.
Corn.-Yields of corn with various rates of fertilizer are
shown in Table 6. Since this experiment was started on virgin
soil, the highest response to fertilizer in the yield of corn was
shown in the first year. During the five years there was a
build up of residual fertilizer in all plots. By the last year the
response to higher rates of fertilization was not significant.
Probably about 20 percent of the increase in yield in all plots
for the last three years was caused by the use of a higher-yield-
ing hybrid, Dixie 18.
Because of favorable weather, corn yields were exceptionally
high in 1949 and 1950 (Table 25). Phosphorus gave a signifi-
cant response in yield for the first four years, nitrogen for the
first three years, and potash for the third and fourth years
only. Correlated soil tests not otherwise reported confirmed the
phosphorus build up and indicated a decrease in potash level
of the virgin soil.
Peanuts.-Yields of peanuts with various rates of fertilizer
are shown in Table 7. Superphosphate gave a highly significant









14 Florida Agricultural Experiment Stations

TABLE 5.-YIELDS OF OATS IN ROTATION AND CONTINUOUS-CROP
EXPERIMENT.

Green Weight of Oats-Pounds
Rotation or Continuous Crop Length 1 1per Acre
__1948 1 1949 1 1950 1951 *
Corn, crotalaria under
Oats under ............................ 1 year 8,860 17,969 14,770 -

Peanuts, lupine under
Corn, lupine under
Corn, oats under .............. 3 years 7,011 11,231 10,686 -
Peanuts, lupine under
Corn, oats for grain
Crotalaria under, oats under 3 years 10,550 20,964 17,356 -

L. S. D. (.05) ..................- .. 966 3,425 4,404
L. S. D. (.01) ...................... 1,462 5,187 6,669

Length Oats for Grain-Bushels per Acre
________1948 1 1949 1 1950 1 1951

Peanuts, lupine under
Corn, oats for grain
Crotalaria under, oats under 3 years 25.9 20.9 23.4 86.3

A severe freeze in February killed the top growth, making harvest impractical.
Red Rustproof No. 14 oats were planted the first three years and Southland oats the
last year.

TABLE 6.-YIELDS OF CORN WITH VARIOUS RATES OF FERTILIZER.

Fertilizer-Pounds per Acre Yield of Corn-Bushels per Acre
Nitrogen I PO KIO 1 1947 1948 1949 1 1950 1951

21 25 20 28.7 37.5 60.4 79.5 63.8
42 50 40 42.5 47.6 75.0 96.8 66.8
63 75 60 50.1 50.3 84.3 99.7 68.1

21 75 60 40.7 44.2 77.8 96.1 70.7
42 75 60 47.1 49.5 82.3 102.3 68.0
63 75 60 50.1 50.3 84.3 99.7 68.1
63 25 60 33.0 40.9 73.1 87.7 65.7
63 50 60 43.1 47.1 82.4 95.1 69.1
63 75 60 50.1 50.3 84.3 99.7 68.1
63 75 20 47.0 47.0 78.8 90.1 69.2
63 75 40 46.8 48.0 83.7 97.9 69.6
63 75 60 50.1 50.3 84.3 99.7 68.1

L. S. D. (.05) .......................... 4.9 6.0 5.1 8.1 5.8
L. S. D. (.01) ...................... 6.7 8.1 6.9 10.9 Not sig.
Florida W-1 hybrid corn was planted the first two years and Dixie 18 hybrid corn the
last three years.








Effect of Rotations and Fertilizers on Crop Yields 15

increase in yield of peanuts the first year on virgin soil. Re-
sponse for other years was not significant. Nitrogen and potash
gave no significant increase for any of the years.

TABLE 7.-YIELDS OF PEANUTS WITH VARIOUS RATES OF FERTILIZER.
Fertilizer-Pounds
per Acre Yield of Unshelled Peanuts-Pounds per Acre
"Nitrogen PO K20 ) 1947 | 1948 1949 1950 1951

4 20 8 1,656 1,924 1,421 1,673 2,620
8 40 16 2,140 2,239 1,208 1,635 2,367
12 60 24 2,248 2,104 1,148 1,523 2,336
4 60 24 2,445 1,991 1,279 1,526 2,353
8 60 24 2,449 2,002 1,189 1,534 2,299
12 60 24 2,248 2,104 1,148 1,523 2,336
12 20 24 1,740 2,033 1,290 1,489 2,106
12 40 24 2,155 2,029 1,271 1,545 2,260
12 60 24 2,248 2,104 1,148 1,523 2,336
12 60 8 2,301 2,126 1,264 1,684 2,249
12 60 16 2,404 2,063 1,193 1,703 2,387
12 60 24 2,248 2,104 1,148 1,523 2,336

L. S. D. (.05) ...........-........... 170 246 Not sig. Not sig. Not sig.
L. S. D. (.01) .-.........---- ..-.... 227 Not sig.

The results show that 400 pounds of 2-10-4 fertilizer was
the most economical for the first two years. For the last three
years 200 pounds per acre of 2-10-4 fertilizer was best for rota-
tion peanuts. There seemed to be enough residual fertilizer
from the other crops grown in the rotation to produce good crops
of peanuts with only the minimal application of fertilizer.

TABLE 8.-YIELDS OF CROTALARIA WITH VARIOUS RATES OF FERTILIZER.
Fertilizer-Pounds
per Acre Green Weight of Crotalaria-Pounds per Acre
POs K2O 19 47 1 1948 1 949 1950 1951
21 15 10,484 27,051 25,025 4,661 5,707
42 30 15,101 38,587 27,770 8,233 10,454
63 45 22,522 38,923 29,505 11,086 10,694
21 45 11,238 31,929 26,855 7,188 8,691
42 45 20,880 37,745 28,728 9,082 9,540
63 45 22,522 38,923 29,505 11,086 10,694
63 15 21,983 39,574 26,833 11,609 11,369
63 30 22,187 37,854 29,164 9,453 10,368
63 45 22,522 38,923 29,505 11,086 10,694

L. S. D. (.05) ------ 1,796 4,492 1,986 2,981 3,845
L. S. D. (.01) .-------. 2,463 6,161 2,724 4,089 Not sig.








16 Florida Agricultural Experiment Stations

Crotalaria.-Yields of crotalaria with various rates of fer-
tilizer are given in Table 8. Phosphorus gave a significant in-
crease in yield of crotalaria for each year except the last. The
results show that when crotalaria was grown in a rotation where
the other crops were well fertilized, there was probably enough
residual fertilizer, except for phosphate, to produce a good
growth.
Oats for Green Manure.-The yield of oats for green manure
with various rates of fertilizer for 1948, 1949 and 1950, are pre-
sented in Table 9. These results show that nitrogen and phos-
phate gave a significant increase in yield of oats in each of the
three years, while potash gave an increase for two years only.

TABLE 9.-YIELDS OF OATS WITH VARIOUS RATES OF FERTILIZER.

Fertilizer-Pounds per Acre Green Weight of Oats-Pounds per Acre
"Nitrogen PO KsO 1 1948 1949 1950 1951

5 25 20 5,309 7,896 9,801 -
10 50 40 6,943 14,157 15,881 -
15 75 60 10,618 22,461 19,874 -
5 75 60 8,576 15,383 16,063 -
10 75 60 9,121 19,194 17,243 -
15 75 60 10,618 22,461 19,874 -
15 25 60 6,671 12,115 11,888 -
15 50 60 9,256 17,424 19,693 -
15 75 60 10,618 22,461 19,874 -
15 75 20 10,482 17,016 15,428 -
15 75 40 9,937 19,330 17,878 -
15 75 60 10,618 22,461 19,874 -

L. S. D. (.05) ............. ............. 740 3,382 3,758
L. S. D. (.01) ............. ........ 1,006 4,597 5,108
A severe freeze in February killed the top growth, making harvest impractical.
Red Rustproof No. 14 oats were planted the first three years and Southland oats the
last year.

Lupine.-Yields of blue lupine with various rates of fertilizer
are given in Table 10. Superphosphate gave a highly significant
increase in yield of blue lupine for 1948 and 1950, and the in-
crease was almost significant in 1949. Since there was con-
siderable potash in the virgin soil, response to added potash
increased each year from very slight in 1948 to significant in
1950. When both phosphate and potash were increased, response
was highly significant for all the years.








Effect of Rotations and Fertilizers on Crop Yields 17

TABLE 10.-YIELDS OF BLUE LUPINE WITH VARIOUS RATES OF FERTILIZER.
Fertilizer-Pounds I
per Acre Green Weight-Pounds per Acre
P._O j K O 1948 1949 1950 1951 *

21 15 6,737 2,788 11,210 -
42 30 11,188 7,101 17,003 -
63 45 12,363 7,006 19,079 -
21 45 7,405 4,850 12,792 -
42 45 12,328 6,883 17,337 -
63 45 12,363 7,006 19,079 -
63 15 11,602 6,650 16,988 -
63 30 11,689 8,364 18,368 -
63 45 12,363 7,006 19,079 -

L. S. D. (.05) ..-............ 2,162 2,486 1,994
L. S. D. (.01) .......---..... 2,965 3,409 2,734
A severe freeze in February completely killed the lupine.

Oats for Grain.-Yields of oats for grain with various rates
of fertilizer are shown in Table 11. Complete fertilizer or phos-
phate alone gave significant increases for three of the first four
years. Potash and nitrogen gave a significant increase in yield
of oats for 1951 only. These results show that, when oats for
grain were grown in rotation with green manure crops, corn, and
peanuts, phosphate was the most needed fertilizer. The overall
increase in yield for 1951 was due to the introduction of the
higher yielding Southland variety.
TABLE 11.-YIELDS OF OATS FOR GRAIN WITH VARIOUS RATES OF
FERTILIZER.

Fertilizer-Pounds per Acre Dry Oats for Grain-Bushels per Acre
Nitrogen I P2O ] KO 1948 1949 1950 1951

21 25 20 15.3 10.9 7.6 48.4
42 50 40 24.6 14.9 22.7 72.9
63 75 60 26.2 14.5 26.1 88.9
21 75 60 26.1 18.9 26.1 70.6
42 75 60 25.4 15.7 21.8 71.9
63 75 60 26.2 14.5 26.1 88.9
63 25 60 16.6 10.5 16.3 59.5
63 50 60 23.6 14.1 21.0 72.3
63 75 60 26.2 14.5 26.1 88.9
63 75 20 19.8 10.4 22.3 67.1
63 75 40 20.4 14.8 23.2 80.8
63 75 60 26.2 14.5 26.1 88.9

L. S. D. (.05) ....................-........---... 7.1 Not sig. 10.5 12.9
L. S. D. (.01) ......-.......-.. ....-..-- ...------ 9.5 14.0 17.2







18 Florida Agricultural Experiment Stations

LIME EXPERIMENT
The lime experiment was a randomized block design with four
replications and four rates of lime on a three-year rotation. The
rates of application were 0, 2,000, 4,000 and 6,000 pounds of
dolomitic lime per acre, applied once at the beginning of the
experiment. The crops in the three-year rotation were the same
as those for the fertilizer experiment. Each crop was grown
every year as previously explained.
At planting time corn and oats for grain received 500 pounds
per acre of 2-10-8 fertilizer. Corn was top-dressed with 32
pounds per acre of nitrogen from Uramon and oats with 32
pounds from nitrate of soda. Oats turned under received an-
nual applications of 500 pounds of 2-10-8 per acre. Peanuts
were fertilized with 400 pounds of 2-10-4 per acre the first three
years and 500 pounds of 2-10-8 fertilizer the last two years of the
test. Bitter blue lupine and Crotalaria spectabilis received an-
nually 300 pounds per acre of 0-14-10 fertilizer.
Corn.-Lime gave a slight increase in the yield of corn (Table
12), but the increase was not significant, except when 4,000
pounds per acre in 1950 and 6,000 pounds per acre in 1949 pro-
duced significant increases over no lime. In 1948 and 1951 lime
at 2,000 pounds per acre gave almost significant increases.
TABLE 12.-YIELDS OF CORN WITH VARIOUS RATES OF LIME.

Dolomitic Lime-Pounds Yield of Corn-Bushels per Acre
per Acre 1947 1 1948 i 1949 1950 1951
0 39.3 41.4 78.2 98.5 69.4
2,000 41.4 45.3 81.9 100.8 74.3
4,000 41.5 42.2 82.4 105.2 69.2
6,000 40.1 43.6 84.7 103.2 70.9

L. S. D. (.05) ......-.............--.......... Not sig. Not sig. 6.1 4.5 Not sig.
Florida W-1 hybrid corn was planted the first two years and Dixie 18 hybrid corn the
last three years.
Peanuts.-Yields of peanuts in the lime test are presented
in Table 13. Lime gave a significant increase in yield for the
first year, probably because of calcium nutrition. Since the
lime was applied at planting time, it did not have time to change
the pH of the soil much during the first growing season. After
the lime had been in the soil over a year the pH increased con-
siderably (Table 14). The increase in pH above 6.48 and the








Effect of Rotations and Fertilizers on Crop Yields 19

possible tie up of minor elements may account for the unfavor-
able growth of peanuts which reduced the yield in 1948. In
1951 lime gave a small but not significant increase in yield of
peanuts, while in 1950 it gave no increase in yield. The low
peanut yields in 1949 probably were caused by wet weather in
August (Table 25), which produced excessive vine growth.
TABLE 13.-YIELDS OF PEANUTS WITH VARIOUS RATES OF LIME.

Dolomitic Lime-Pounds Yields of Unshelled Peanuts-Pounds per Acre
per Acre 1947 1 1948 1 1949 1 1950 1951
0 1,631 1,763 1,099 1,650 1,914
2,000 1,890 1,661 1,133 1,631 2,346
4,000 1,911 1,526 1,001 1,609 2,123
6,000 1,986 1,515 I 1,095 1,639 2,020

L. S. D. (.05) ............... 214 158 Not sig. Not sig. Not sig.
L. S. D. (.01) .................... 296 Not sig.

Peanuts were dusted with about 60 to 80 pounds of elemental
sulfur-DDT mixture per acre each year to control leaf spot. The
sulfur made the soil more acid. Twenty-seven months after one
ton of lime had been applied, the soil had reached about the
same pH as before the liming (Table 14). This would indicate
that lime should be applied about every two or three years to
maintain the initial reaction in the soil, but less frequently if no
sulfur is applied.
TABLE 14.-THE PH OF THE SOIL OF PEANUT PLOTS WITH VARIOUS
RATES OF LIME.

Dolomitic Lime- pH Before pH of Soil Months After Treatment
Pounds per Acre Treatment With Lime
1947 15 21 27
0 5.53 5.60 1 5.46 5.14
2,000 5.59 6.13 5.99 5.71
4,000 5.58 6.48 6.62 6.07
6,000 5.54 6.69 6.90 6.54

Crotalaria.-Yields of crotalaria are shown in Table 15. In the
first year of the test lime produced a significant increase; this
was probably caused by an increase in available calcium. For
the next four years lime gave no increase in yield of crotalaria.








20 Florida Agricultural Experiment Stations

Oats for Green Manure.-Yields of oats for green manure are
presented in Table 16. One ton of lime gave an almost significant
increase in yield of oats for green manure in 1948, but only

TABLE 15.-YIELDS OF CROTALARIA WITH VARIOUS RATES OF LIME.

Dolomitic Lime- Green Weight of Crotalaria-Pounds per Acre
Pounds per Acre 1947 1 1948 1949 I 1950 1951

0 18,208 34,587 25,472 15,311 13,634

2,000 24,379 30,550 25,526 14,527 13,961

4,000 22,753 31,407 24,306 12,262 14,680

6,000 22,564 32,075 24,394 13,973 13,612

L. S. D. (.05) ........- 3,641 Not sig. Not sig. Not sig. Not sig.
L. S. D. (.01) .......... 5,236

TABLE 16.-YIELDS OF OATS FOR GREEN MANURE WITH VARIOUS RATES
OF LIME.

Dolomitic Lime- Green Weight of Oats-Pounds per Acre
Pounds per Acre 1948 1949 1950 1951 *

0 7,623 16,013 14,248 -

2,000 9,121 18,922 15,518 -

4,000 8,712 15,655 16,970 -

6,000 9,665 14,157 13,885 -

L. S. D. (.05) ...........-. 1,541 Not sig. 2,521
A severe freeze in February killed the top growth, making harvest impractical.
Red Rustproof No. 14 oats were planted the first three years and Southland oats the
last year.

TABLE 17.-YIELD OF LUPINE WITH VARIOUS RATES OF LIME.

Dolomitic Lime-- Green Weight-Pounds per Acre
Pounds per Acre 1948 1949 1950 1951 *

0 9,607 7,841 17,439 -

2,000 12,081 7,275 18,498 -

4,000 12,458 8,131 20,895 -

6,000 11,601 5,735 19,210 -

L. S. D. (.05) ............ 1,684 Not sig. Not sig.
L. S. D. (.01) ............ 2,421
A severe freeze destroyed the lupine crop.








Effect of Rotations and Fertilizers on Crop Yields 21

slight increases in 1949 and 1950. Yields were slightly lower
at higher rates of lime for the last two years.
Lupine.-Yields of lupine are given in Table 17. One ton of
lime per acre gave a highly significant increase in yield of lupine
the first year. Two tons of lime gave an increase in yield of
blue lupine in the second and third years of the test, but the
difference was not significant at the 5 percent level.
Oats for Grain.-Yields of oats for grain (Table 18) showed
no significant response to lime during the experiment.
TABLE 18.-YIELDS OF OATS FOR GRAIN WITH VARIOUS RATES OF LIME.

Dolomitic Lime-- Dry Oats for Grain-Bushels per Acre
Pounds per Acre 1948 1949 1950 1951

0 21.1 17.0 38.8 79.4
2,000 25.0 17.3 29.8 77.4
4,000 23.2 1 18.0 27.9 88.5
6,000 23.1 24.6 24.0 76.2

L. S. D. (.05) ............ Not sig. Not sig. Not sig. Not sig.
Red Rustproof No. 14 oats were planted the first three years and Southland oats the
last year.

HARVESTING VERSUS HOGGING-OFF PEANUTS

The harvesting versus hogging-off peanut experiment was
a comparison of two systems of soil management with continuous
peanuts. One system was hogging-off; the other was harvesting
nuts and hay and following with lupine. Peanuts were fertilized
the same as those in the rotation experiment, and lupine re-
ceived 300 pounds of 0-14-10 per acre for each of the five years.
TABLE 19.-YIELDS OF CONTINUOUS PEANUTS IN THE "HOGGED-OFF" AND
HARVESTED PEANUT EXPERIMENT.

Continuous Crop _Unshelled Peanuts-Pounds per Acre
1947 1948 1949 1950 1951 Average

Hogged-off*
peanuts .-- 2,548 1,161 857 1,869 2,033 1,694
Harvested
peanuts ... 2,548 1,202 960 1,371 2,044 1,625

L. S. D. (.05) .... Not sig. Not sig. Not sig. 162 Not sig.
L. S. D. (.01) .... 297
Average yields based on measured yields from small fenced plots.







22 Florida Agricultural Experiment Stations

Yields of peanuts are shown in Table 19. Continuous peanuts
harvested and followed by lupine for green manure made about
the same average yield as continuous peanuts hogged-off for the
five-year period.

CHEMICAL STUDIES OF SOILS AND PLANTS
Plots were selected from the rotation, fertility and lime ex-
periments for chemical study. The object was to compare the
concentration of some of the important nutrients in soil and
plants and to correlate these findings with crop yield. The
treatments used are shown in Tables 20 and 21. All the rotation
plots sampled were planted in peanuts in 1949 and corn in 1950.
The continuous peanut plots were sampled in 1949 and the con-
tinuous corn plots in 1950.
Plant and soil analyses data (3) appear in Tables 20 and 21.
Soils were extracted with ammonium acetate buffered at pH 4.7.
Potassium, calcium and magnesium were determined by the
flame photometer and phosphorus colorimetrically. Plant ma-
terial was ashed and then analyzed in the same manner.
Peanut Plots.-Soils of duplicate peanut plots were sampled
nine times at two-week intervals beginning May 5, 1949, and
ending September 1, 1949. The average of the eighteen samples
was used. Plant samples were taken on August 12 and Septem-
ber 12 from duplicate plots and the average of four samples
was used.
Chemical analyses of soil and plants from the peanut plots
and yield of peanuts for 1949 are given in Table 20. Increasing
the rate of phosphate and of potash increased the phosphorus
and potassium contents of the soil and peanut plants, but did
not increase the yield of peanuts. When the rate of dolomitic
lime was increased, phosphorus, calcium and magnesium contents
of the soil and phosphorus and magnesium contents of the pea-
nut plants were increased, but yield was not affected.
Potassium and calcium contents of soil and plants and yield
of peanuts were lower where peanuts were grown continuously
than where peanuts were grown every other year in a rotation.
Potassium, calcium, and magnesium contents of the soil and
potassium content of the plants were lower where peanuts were
grown every other year than where peanuts were grown every
third year in a rotation. Results indicate that continuous pea-
nuts more rapidly deplete the soil of potassium, calcium and mag-
nesium than do the rotations.






TABLE 20.-CHEMICAL ANALYSES OF SOIL AND PLANTS FROM PEANUT PLOTS AND YIELDS OF PEANUTS FOR 1949.

Fertilizer*-Pounds per Acre Soil Analyses-Parts per Million Plant Analyses-Percent Unshelled Peanuts
SPounds per Acre Z
N PO, KO Dolomite pH P K Ca Mg _P K CaI Mg

12 20 24 0 5.19 1.9 64.7 228 3.3 0.170 2.63 1.00 0.49 1,290
12 40 24 0 5.14 3.8 67.5 260 4.0 0.205 2.49 0.95 0.52 1,271
12 60 24 0 5.14 6.4 58.8 295 4.3 0.220 2.11 0.95 0.50 1,148
12 60 8 0 5.08 7.3 46.2 321 4.5 0.220 1.40 1.24 0.63 1,264
12 60 16 0 5.08 6.6 50.9 277 2.8 0.210 1.97 1.01 0.53 1,193
12 60 24 0 5.14 6.4 58.8 295 4.3 0.220 2.11 0.95 0.50 1,148

8 40 16 0 5.25 5.0 53.4 237 6.2 0.220 2.25 0.87 0.56 1,099
8 40 16 2,000 5.82 5.3 52.1 371 40.3 0.215 1.81 0.79 0.69 1,133
8 40 16 4,000 6.13 8.9 58.5 513 69.7 0.250 2.01 0.79 0.73 1,001
8 40 16 6,000 6.69 10.2 55.3 634 113.7 0.300 1.99 0.93 0.85 1,095

Rotation or
Continuous Crop Length
Peanuts, native cover 1 year 4.95 4.1 33.1 176 0.4 0.215 0.94 0.74 0.58 818

Peanuts, lupine under
Corn, native cover.... 2 years 5.05 4.1 39.8 185 0.6 0.200 1.51 0.87 0.51 1,080
Peanuts, lupine under
Corn, oats for grain
Crotalaria under, oats
under ......................... 3 years 5.21 4.6 54.6 257 6.4 0.210 2.05 0.87 0.56 1,022

Rotation or continuous-crop plots received 8 pounds nitrogen, 40 pounds PsOs and 16 pounds of KXO per acre.
42% uramon, 18% superphosphate, and 60% muriate of potash were used as sources of nitrogen, P2Os and K2O, respectively.
WS









LO
TABLE 21.-CHEMICAL ANALYSES OF SOILS AND PLANTS FROM CORN PLOTS AND YIELDS OF CORN FOR 1950.

Fertilizer*-Pounds per Acre Soil Analyses-Parts per Million Plant Analyses-Percent Yield of Corn
S I I | | Bushels per Acre
N P2O K2O Dolomite pH P K aCa Mg P K Ca Mg re

63 25 60 0 5.28 2.25 38.8 216 14.5 0.175 2.17 0.91 0.320 87.5
63 50 60 0 5.25 4.20 37.9 282 13.5 0.205 1.93 1.04 0.320 95.1
63 75 60 0 5.23 5.60 36.2 393 14.0 0.220 1.79 1.07 0.395 99.7
63 75 20 0 5.19 6.00 33.4 318 13.0 0.200 1.28 1.31 0.515 90.1
63 75 40 0 5.26 6.90 39.5 308 13.5 0.200 1.53 1.19 0.415 97.9
63 75 60 0 5.23 5.60 36.2 393 14.0 0.220 1.79 1.07 0.395 99.7

42 50 40 0 5.40 6.95 33.2 335 19.0 0.200 1.60 1.04 0.460 98.5
42 50 40 2,000 5.77 7.85 32.9 452 30.5 0.220 1.52 0.97 0.600 100.8
42 50 40 4,000 6.04 8.75 36.4 622 54.5 0.235 1.51 1.02 0.685 105.2
42 50 40 6,000 6.64 15.60 33.0 735 90.0 0.245 1.45 0.99 0.765 103.2
Ti
Rotation or ,
Continuous Crop Length .

Corn, native cover .... 1 year 5.50 6.75 29.0 251 12.5 0.145 1.53 0.58 0.350 57.8
c+t
Peanuts, lupine under
Corn, native cover .... 2 years 5.21 4.35 30.0 260 13.0 0.175 1.40 0.86 0.490 84.0
R.
Peanuts, lupine under '
Corn, oats for grain
Crotalaria under, oats
under .................. 3 years 5.21 5.85 33.5 310 13.5 0.180 1.42 0.98 0.460 93.2

Rotation or continuous-crop plots received 42 pounds nitrogen, 50 pounds P0Os and 40 pounds K2O per acre.
42% uramon, 18% superphosphate and 60% muriate of potash were used as sources of nitrogen, P-Os and KnO, respectively.








Effect of Rotations and Fertilizers on Crop Yields 25

Corn Plots.-Soil samples were taken from duplicate corn
plots March 28, May 18, June 26, July 13 and August 31, 1950,
for chemical analysis; the average of 10 soil samples was used.
Plant samples were taken from duplicate corn plots on May
18, June 26, July 13 and August 31. The average chemical
composition of eight plant samples was used.
Chemical analyses of soils and plants from corn plots and
yield of corn for 1950 are shown in Table 21. As the rate of
phosphate was increased the phosphorus and calcium contents
of the soil and corn plants and the yield of corn increased. When
the rate of potash was increased the potossium contents of the
soil and plants and the yield of corn increased. As the po-
tassium content of the corn plants increased the calcium con-
tent decreased. When the rate of dolomitic lime was increased
the phosphorus, calcium and magnesium contents of the soil, the
phosphorus and magnesium contents of the corn plants, and the
yield of corn increased slightly.
Calcium and magnesium contents of soil and plants and yield
of corn were lower in continuous corn than in corn in rotation.
The phosphorus content of the corn plants was much lower in
the continuous than in the rotation corn. However, the available
phosphorus content of the soil was much higher in the continuous
than in the rotation corn. While the chemical method used
(extracting with .002 N H2SO) (6) showed the phosphorus to
be available, plant analysis showed that the continuous corn
was unable to use as much of the phosphorus as the rotation
corn.
It seems that legumes in the rotations used phosphorus; and
when they were turned under, they added to the soil considerable
organic phosphorus that did not show in the chemical soil test
for available phosphorus. As this organic phosphorus decom-
posed, it was used by the corn plant, resulting in a higher phos-
phorus content. Part of the inorganic phosphorus was fixed by
the soil before it could be used by the corn, while the organic
phosphorus decomposed slowly during the growing season and
could be used by the corn before it became unavailable. Also
the decomposition of the organic matter tended to make some
of the fixed phosphorus available.
In another experiment (4) soil tests showed that this soil
type fixed a very large amount of inorganic phosphate, which
was partly made available later. This may explain why corn
shows phosphorus deficiency symptoms early in the spring and








26 Florida Agricultural Experiment Stations

then later recovers. Because this soil has the capacity to fix
large amounts of phosphorus, most crops need more phosphorus
than nitrogen or potassium fertilizers.

ORGANIC MATTER AND MOISTURE EQUIVALENT
STUDIES

The moisture equivalent (1) and organic matter (Walkley
Method) (7) of the soils from the plots of the fertility experiment
for the first and fifth years of the test are shown in Table 22.
The moisture equivalent and organic matter decreased in all
plots for the five-year period. The loss in organic matter was
considerable in all plots.
TABLE 22.-MOISTURE EQUIVALENT AND ORGANIC MATTER OF SOIL FROM
PLOTS OF THE FERTILIZER EXPERIMENT FOR 1947 AND 1951.

Fertilizer-Pounds Percent Moisture
per Acre Percent Organic Matter Equivalent
Nitro-
gen I PO, I KO 1947 1951 Loss 1947 1951 Loss
21 25 20 2.47 1.78 0.69 8.1 6.50 1.60
42 50 40 2.09 1.80 0.29 8.0 6.37 1.63
63 75 60 2.40 1.81 0.59 8.1 6.53 1.57
21 75 60 2.16 1.98 0.18 8.0 6.60 1.40
42 75 60 2.29 1.80 0.49 7.7 6.37 1.33
63 75 60 2.40 1.81 0.59 8.1 6.53 1.57
63 25 60 2.44 1.82 0.62 7.9 6.46 1.44
63 50 60 2.52 1.80 0.72 7.7 6.17 1.53
63 75 60 2.40 1.81 0.59 8.1 6.53 1.57
63 75 20 2.41 1.86 0.55 7.6 6.49 1.11
63 75 40 2.42 1.83 0.59 8.0 6.51 1.49
63 75 60 2.40 1.81 0.59 8.1 6.53 1.57


The moisture equivalent and organic matter of the soil from
the plots of the rotation and continuous crop experiment for the
first and fifth years of the test are given in Table 23. The
greatest loss of organic matter in continuous cropping systems
occurred in the peanuts plots with poor lupine crops or none
turned under. The smallest loss took place in the continuous
corn plots.
The three-year rotation (peanuts, lupine under, corn, oats
for grain, crotalaria under, oats under) showed the smallest loss
of organic matter of all the rotations tested. In this rotation
five crops of vegetation (lupine, corn stalks, oats straw, cro-





TABLE 23.-MOISTURE EQUIVALENT AND ORGANIC MATTER FROM PLOTS OF THE ROTATION AND CONTINUOUS-CROP
EXPERIMENT FOR 1947 AND 1951.

Percent Moisture Equivalent Percent Organic Matter
Rotation or Continuous Length I I I
Crop 1947 1951 Plot Loss IRotation Loss 1947 1951 Plot Loss jRotation Loss

Peanuts, native cover .... 1 year 8.61 6.36 2.25 2.25 2.12 1.37 0.75 0.75
Peanuts, lupine under .... 1 year 8.59 6.06 2.53 2.53 2.11 1.31 0.80 0.80
Corn, crotalaria under,
Oats under ................... 1 year 8.59 6.57 2.02 2.02 2.03 1.61 0.42 0.42
Corn, crotalaria under .. 1 year 8.58 6.52 2.06 2.06 2.08 1.51 0.57 0.57
Corn, lupine under ....... 1 year 8.62 6.57 2.05 2.05 1.95 1.57 0.38 0.38
Corn, native cover ........ 1 year 8.65 6.49 2.16 2.16 2.07 1.49 0.58 0.58
Peanuts, lupine under .... 2 years 8.55 6.63 1.92 2.21 2.09 1.54 0.55 0.57
Corn, native cover ........ 8.62 6.12 2.50 2.03 1.44 0.59
Peanuts, lupine under .... 2 years 8.62 6.44 2.18 2.37 2.12 1.50 0.62 0.62
Corn and velvet beans
interplanted .................. 8.58 6.02 2.56 1.98 1.37 0.61
Peanuts, lupine under .... 2 years 8.62 6.49 2.13 2.15 2.13 1.54 0.59 0.55 S
Corn, crotalaria under .. 8.58 6.42 2.16 2.06 1.56 0.50 o
Peanuts, lupine under .... 3 years 8.59 6.56 2.03 2.17 1.94 1.52 0.42 0.62
Corn, lupine under ........ 8.58 6.11 2.47 2.12 1.32 0.80
Corn, oats under .......... 8.59 6.58 2.01 2.17 1.52 0.65
Peanuts, lupine under .... 3 years 8.58 6.71 1.87 1.93 1.99 1.68 0.31 0.47
Corn, oats for grain .... 8.59 6.33 2.26 2.08 1.48 0.60
Crotalaria under,
Oats under ................. 8.59 6.94 1.65 2.23 1.74 0.49

L. S. D. (.05) ............... Not sig. 0.48 0.30 Not sig. 0.20 0.05
L. S. D. (.01) ................. 0.63 0.39 0.27 0.07







TABLE 24.-NEMATODE POPULATION, SOIL ORGANIC MATTER AND YIELD OF PEANUTS AND CORN IN THE ROTATION AND
CONTINUOUS-CROP EXPERIMENT FOR 1951.
00

Rotation or Continuous Crop Length Nematode Percent Or- Peanuts Lbs. Corn Bushels
Count ganic Matter per Acre per Acre

Peanuts, native cover under .---.------- 1 year 48 1.37 2,010

Peanuts, lupine under .....--...............-.---- 1 year 161 1.31 1,887

Corn, crotalaria under, oats under .---........... 1 year 346 1.61 63.4

Corn, crotalaria under -- ............... .........---- 1 year 345 1.51 61.7

Corn, lupine under .....---..--....--.........- ....... 1 year 354 1.57 57.1

Corn, native cover under- .-...-.................-.... 1 year 333 1.49 49.4

Peanuts, lupine under .................... ... ......... 2 years 229 1.54 2,221
Corn, native cover under ............. ....... 153 1.44 61.7 t

Peanuts, lupine under ..................... ....... .... 2 years 234 1.50 2,412
Corn and velvet beans interplanted .................. 359 1.37 59.0

Peanuts, lupine under .--........ -.---.......-...-- 2 years 241 1.54 2,343
Corn, crotalaria under ................ .... ........ -------356 1.56 63.7

Peanuts, lupine under ........--............- ........ 3 years 242 1.52 2,197
Corn, lupine under ................ ........... .. .......... 601 1.32 63.2
Corn, oats under ..... ......................... ........ 390 1.52 68.8

Peanuts, lupine under ....................--.. -......... . 3 years 214 1.68 2,309
Corn, oats for grain .........--........... -----................ 368 1.48 63.8
Crotalaria under, oats under ................................ 442 1.74

L. S. D. (.05) ........... --.... ........-----------.... ......226 0.20 224 5.8
L. S. D. (.01) ...........-..........- ----...... ...... 296 0.27 307 7.9

Soil sampled for nematode population April 30, May 20 and May 26, 1952.








Effect of Rotations and Fertilizers on Crop Yields 29

talaria and oats) were added to the soil in the three-year period.
In the, Walkley Method, the content of organic matter was de-
termined by multiplying the amount of organic carbon in the
soil by the conventional factor of 1.724. Since the carbon/nitro-
gen ratio in virgin soil may differ from that in soil cultivated
for five years, the loss of carbon for the five-year period may
have been more than the loss of nitrogen.
These results show that, even with the best cropping sys-
tems, it was not possible to maintain the organic matter content
in Norfolk loamy fine sand for the first five years after the virgin
soil was put under cultivation. Corn yields increased during
the five years, indicating a build up of limiting plant nutrients.
With the best cropping systems, it is believed that there prob-
ably will not be an additional loss of organic matter during the
next five years of cultivation. However, with continuously har-
vested peanuts the soil might continue to lose organic matter.
There was a correlation- between the loss in moisture equiva-
lent and the loss in organic matter for the five-year period. This
could be expected, since the moisture equivalent is largely de-
pendent on the organic matter content of a loamy fine sand.
The three-year rotation given above showed the smallest loss
in moisture equivalent, while continuous corn plots with a green
manure crop had the next smallest loss. Continuous peanuts
with lupine in winter showed the largest loss in moisture equiva-
lent.
Since most soils in Florida are very low in clay content, the
humus or decomposed organic matter constitutes the main part
of the base exchange capacity of these soils (5). Therefore a
23-percent average loss of decomposed organic matter (Table
23) results in a large loss of base exchange capacity.

NEMATODE STUDIES
Samples were collected from all plots of the rotation experi-
ment and the nematode population was determined by the modi-
fied Baermann funnel method (2). Total nematode population,
content of soil organic matter, and yield of peanuts and corn
in the rotation and continuous crop experiment for 1951 are
given in Table 24.
Soil in continuous peanuts has a significantly lower number
of nematodes than soils in continuous corn. In the rotations,
peanut plots had a lower nematode population than the corn
plots. Native cover seems to depress the nematode count in the








30 Florida Agricultural Experiment Stations

soil, while lupine and crotalaria increase the count. Since there
was some positive relationship between percent organic matter
of the soil and nematode population, the populations in all likeli-
hood contained many saprophitic nematodes. This may have
concealed response to the type of cover crop as well as cash
crop.

TABLE 25.-MONTHLY RAINFALL IN INCHES AT THE NORTH FLORIDA
EXPERIMENT STATION.

Month 1947 1948 1949 1950 1951

January .... ....... 6.16 5.05 1.89 0.66 1.59
February .....-........... 3.31 1.02 4.90 1.21 1.63
March ...................... 6.08 13.58 5.47 5.44 10.28
April ................... .. 9.17 14.25 7.60 5.29 2.06
May ......................... 7.80 2.35 1.54 5.19 8.02
June .......................... 5.89 4.71 6.76 6.41 3.88
July .......................- 4.96 11.24 8.03 5.76 4.18
August ................ 4.89 6.63 9.36 4.69 4.84
September .............. 5.00 6.27 1.35 2.81 3.54
October .................... 3.68 3.33 4.98 1.54 1.69
November -............... 12.26 4.60 1.93 0.39 6.65
December ............- 5.56 4.41 3.78 3.47 7.76

Total ................... 74.76 77.44 57.59 42.86 56.12

SUMMARY AND CONCLUSIONS

Field plots in replicated randomized blocks were established
on virgin soil consisting mostly of Norfolk loamy fine sand to
determine the effect of various rotations and continuous crops,
fertilizers, lime and green manure crops on yield of peanuts,
corn and oats, and on the fertility of the soil.
Corn grown in rotation with green manure crops yielded sig-
nificantly higher than continuous corn with native cover. Pea-
nuts grown in rotation with corn and green manure crops yielded
an average of about 100 to 200 pounds per acre more than con-
tinuous peanuts.
In 1952 continuous lupine following peanuts yielded 2,220
pounds per acre of green weight, compared to 8,371 pounds for
lupine grown once in a three-year rotation. Diseases common
to both peanuts and lupine, such as Rhizoctonia spp. and Scle-
rotium rolfsii Sacc., made it appear desirable to grow lupine
following peanuts not oftener than once in three years.
Corn, peanuts, crotalaria, oats and lupine showed a response
to fertilizer. After four years there was a buildup of residual








Effect of Rotations and Fertilizers on Crop Yields 31

fertilizer in the soil, so that the increase in yield was small as the
rate of fertilizer was increased above the minimal application
used.
Corn, crotalaria, lupine and oats gave significant responses
to phosphate fertilizer for the five-year period. Corn and oats
for green manure gave a significant response to nitrogen, but
only a small response to potash. Peanuts gave no response to
nitrogen, while peanuts, crotalaria and lupine gave a small,
non-significant response to potash.
Lime gave a significant increase in the first year in the yield
of peanuts, crotalaria, lupine and oats for green manure.
For the five-year period, continuous peanuts hogged-off, fol-
lowed by native cover, yielded about the same as continuous pea-
nuts harvested and followed by lupine for green manure.
Increasing the rate of phosphate and potash applied to the soil
increased the phosphorus and potassium contents of the soil and
peanut plants, but did not increase yield of peanuts.
As the rate of dolomitic lime applied to the soil was increased,
the phosphorus, calcium and magnesium contents of the soil and
the phosphorus and magnesium contents of the peanut plants
were increased, but yield was not increased. The potassium and
calcium contents of the soil and plants as well as the yield of
peanuts were lower where peanuts were grown continuously than
where peanuts were grown once in a three-year rotation.
Chemical analysis showed soil phosphorus to be available,
but plant analysis showed that continuous corn did not take
up as much of the phosphorus as corn in the rotation. It may
be that legumes could use this phosphorus; when they were
turned under, they added to the soil considerable organic phos-
phorus that did not show in the chemical soil test for available
phosphorus. As this organic phosphorus decomposed slowly,
it was used by the corn plants before it could be fixed in un-
available form. On the other hand, part of the inorganic phos-
phorus was fixed by the soil before it could be used by the corn
crop.
The soils of all plots declined in moisture equivalent and in
organic matter content for the five-year period, even though com-
paratively large amounts of plant residue were returned to the
soil. The greatest loss of organic matter in continuous cropping
systems occurred in the peanut plots. The smallest loss took
place in the corn plots.








32 Florida Agricultural Experiment Stations

The smallest loss of organic matter of all the rotations tested
was in the three-year rotation (peanuts, lupine under, corn,
oats for grain, crotalaria under, oats under). There was a
smaller loss of organic matter in the continuous corn with lu-
pines, or with crotalaria and then oats for green manure, than
any of the two-year rotations.
As diseases, such as Rhizoctonia spp. and Sclerotium rolfsii
Sacc., were carried from the continuous peanuts to the lupine
crop following, many of the seedlings were killed. The yield of
lupine was very low for 1949 and 1952. This poor growth of
lupine had about the same influence as native cover on yield of
peanuts.
Where peanuts were grown continuously, the nematode popu-
lation of the soil was significantly lower than with continuous
corn.
ACKNOWLEDGMENTS
The authors are indebted to: Dr. F. B. Smith for his constructive
criticism throughout the experiment; Dr. G. M. Volk for his assistance
in the initial planning of the experiment; Dr. J. R. Neller and Dr. Nathan
Gammon, Jr., for their participation on the project in 1947 and 1948;
Dr. W. L. Pritchett for his assistance in 1949; Dr. R. W. Prevatt for
chemical analyses of 1949 and 1950 samples; and to Mr. Joseph M. Good,
Jr., for nematode studies. Professor W. D. Hanson was consulted relative
to the statistical analysis. Criticisms and suggestions by the late J. D.
Warner are gratefully acknowledged.

LITERATURE CITED
1. BRIGGS, L. J., and J. W. McLANE. The moisture equivalent of soils.
U.S.D.A. Bur. of Soils., Bul. 45. 1907.
2. CHRISTIE, J. R., and V. G. PERRY. Removing nematodes from the soil.
Proceedings of Helminthology Society of Washington. Vol. 18, No.
2. July 1951.
3. PREVATT, R. W. Unpublished Master's Thesis. Soils Dept., Univ. of
Fla. 1951.
4. PRITCHETT, W. L. Unpublished data. Soils Dept., Univ. of Fla. 1949.
5. THOMPSON, L. G., JR., and F. B. SMITH. Organic matter in Florida
soils. Fla. Agr. Exp. Sta. Bul. 433. 1947.
6. TRUOG, E. The determination of readily available phosphorus of soils.
Jour. Am. Soc. Agron. 22: 974-982. 1930.
7. WALKLEY, ALLEN. A critical examination of a rapid method for deter-
mining organic carbon in soils. Effect of variations in digestion
conditions, and of inorganic constituents. Soil Science 63: 251-264.
1947.





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