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~/:' Agricultural Research and Education Center
IFAS, University of Florida
S AREC Bradent'?n Research Report GC1978-1 July 1978
UTILIZATION OF RESIDUAL FERTII OF A FALL 'TOMATO
CROP BY DIRECT SEEDED AND TA LA TED VEQgTALES
A. A. Cs 4nszkyz)
Soil analyses of harvested tomato elds sed substantial amounts of resid-
ual fertilizers remaining in the land in e fq. of soluble salts. Soil surveys
of tomato fields also revealed a gradual acc tion of salt in the soil where
tomatoes were planted for several seasons. Gr vers have three methods available
to prevent the buildup of soluble salts in the soil caused by the application of
high amounts of fertilizers:
1) move to new land which has a low total soluble salt (TSS) content
2) leach out the excess salt from the fields between growing seasons, and
3) grow catch crops utilizing the residual salts.
Abandoning cultivated field and moving to new land is not always feasible
or practical. In the future, pending proposals on water quality by regulatory
agencies will make it difficult to remove the residual fertilizers from the soil
by leaching. These agencies claim that fertilizers in the runoff waters contam-
inate surrounding lands and waterways. Thus, planting of a catch crop to reduce
the TSS control of the soil and to prevent the buildup of salts in tomato fields
seems to be the correct solution, both from an environmental as well as economic
Economic studies by IFAS indicate that in 1976, $476 per acre was spent for
plastic mulch and fertilizers in the production of one crop of full-bed-plastic
mulch staked tomatoes. Part of this amount could be saved if the tomato fields
were second cropped after harvest of the fall crop.
In this report the results of an experiment are summarized in which direct
seeded and transplanted vegetable crops were grown in the spring season following
a fall tomato crop. The vegetable crops were grown with and without additional
fertilizer to investigate the possibility of utilizing residual fertilizers.
Materials and Methods
In the spring of 1976 nine different vegetable crops, four direct seeded and
five transplanted, were grown in land previously planted to a staked, full bed
plastic mulch, fall tomato crop. The fall tomato crop received 14.5 lbs of
18-0-25-2 and 5.2 Ibs of 20% superphosphate with micronutrients per 100 row feet.
In order to compare the effect of residual and added fertilizers on the vegetable
crops, one half of each plot was treated in the spring with the equivalent of 1.23
Ibs NH4N03, 5.2 Ibs superphosphate with micronutrients and 11.7 lbs KN03 per 100
row feet. Plant materials and plastic mulch were removed approximately 3 weeks
before spring planting and beds 30 in. wide were reformed in place and covered
with new plastic. The superphosphate was applied broadcast on top of the bed;
the rest of the fertilizer was worked into the top 2 in. of the soil.
Seeds of radish (Scarlet Globe), lettuce (Bibb), green onions (Evergreen
White Bunching), and carrots (Danvers Half Long) were sown in rows after cutting
a slit approximately 1 inch wide in the plastic mulch Cbver. Green onions and
lettuce were sown in double rows, carrots and radish in triple rows.
Five-week old seedlings of broccoli (Greeh Comet Hybrid), cabbage (Golden
Acre), cauliflower (Snow King Hybrid, kohlrabi (Early White Vienna), and zucchini
squash (Fordhook) were transplanted the first week of March. Within row planting
distances between plants were: 18 inches for broccoli, cabbage, and cauliflower,
6 inches for kohlrabi and 30 inches for zucchini.
Soil samples for TSS and pH determinations were taken from the nonfeftilized
and fertilized plots before and after the fertilizer application. Water was pro-
vided by seep irrigation throughout the growing season. Plants were sprayed twice
weekly with approved pesticides.
Results and Discussion
Seeds of carrots, green onion and lettuce failed to germinate in the ferti-
lized plots and radish germinated very poorly. In the plots which had residual
fertilizers only, carrot and lettuce seed germination was also inhibited by the
high TSS content of the soil. Green onions and radish yielded satisfactorily on
the residual fertilizers when compared to the reported Florida average yields for
these crops (Table 1).
Table 1. Total soluble salt content of soil at sowing time and yields of direct
Carrots 1 Green onions Lettuce 1 Radish
Treatment Treatment Treatment Treatment
R F R F R F R F
TSS, 0-6 in. soil
depth (ppm) 12,475 26,150 13,575 30,575 13,150 27,900 14,900 23,950
Yield/acre 7112 0 17,3762 0 1.063 0 31,5562 5,356
Treatment: R = residual fertilizer, F = fertilized
2Bunch, 6 plants per bunch
Seedling survival of the cole crops in the fertilized plots was poor. Further-
more, the yield of individual plants in these plots was also less than the yield
per plant in the nonfertilized plots. The combination of lower per plant yield
and reduced seedling survival in the fertilized plots resulted in significantly
lower per acre yields compared to nonfertilized treatments (Table 2).
Kohlrabi had the least tolerance to the high soil TSS content; only 21% of
the transplants survived. Cabbage had a transplant survival of 65%, cauliflower
55% and broccoli 45% in the fertilized plots. Zucchini squash transplants sur-
vived the high soil salt content; however, in the early stages of development
the plants were stunted and often wilted during the daytime.
Plants grown on residual fertilizer also showed signs of salt injury. None
of the cole crops had a 100% seedling survival (Table 2). The present work shows
that residual fertilizers remaining in the soil after a fall tomato crop may be
sufficiently high for the production of a spring crop. A survey of the land for
soil TSS content should be made, however, in every case when planting of a catch
crop is attempted after a fall crop, to determine the intensity (i.e. the amount)
and the balance (i.e. the types) of residual plant nutrients.
ACKNOWLEDGMENTS: This work was supported by a grant from the Florida Tomato
Exchange which is gratefully acknowledged.
Geraldson, C. M.
with plant gr
Geraldson, C. M.
Soil soluble salts determination of and association
Proc. Fla. State Hort. Soc. 70:121-126.
1966. Effect of salt accumulation in sandy spodosols on tomato
Proc. Soil and Crop Sci. Soc. of Fla. 26:6-12.
Hayslip, M. C., E. M. Hodges, D. W. Jones, and A. E. Kretschmer, Jr. 1964. Tomato
and pangolagrass rotation for sandy soils of south Florida. Univ. of Fla.
Agri. Exp. Sta. Circ. S-153.
Kretschmer, A. E., Jr., N. C. Hayslip, and W. T. Forsee,
corn and sorghum production after fall vegetables.
Sta. Circ. S-145.
Jr. 1963. Spring field
Univ. of Fla. Agri. Exp.
Marlowe, G. A., Jr., and C. M. Geraldson. 1976. Results of a soluble salt survey
of commercial tomato fields in southwest Florida. Proc. Fla. State Hort. Soc.
Otte, J. A. 1976. Calculating costs and breakeven prices for full bed plastic
mulch staked tomatoes. Univ. of Fla., IFAS Economic Info. Report 59.
Westgate, P. J. 1950. Effects of soluble soil salts on vegetable production at
Sanford. Proc. Fla. State Hort. Soc. 63:116-123.
Table 2. Total soluble salt content of soil at planting time and yields of transplanted vegetables.
+ Zucchini 1
Total soluble salts
0-6 in. soil depth
% of seedling
Yield per plant (Ibs)
Yield per acre (tons)
Treatment: R = residual fertilizer, F = fertilized