Progress Report Series No. 102 MARCH 1973 Agricultural Experiment Station R. Dennis Rouse, DirecLor Auburn, Alabama AUBURN UNIVERSITY ~~~I IIIILPI~ Soil Fertility Experiments with Tomatoes 1971-72 Clyde G. Evans, W. A. Johnson, and Dallas -lartzog 1 between tomato growers in Geneva County and Auburn University Agricultural Experiment Station was initiated in 1970 and continued in 1971 and 1972.2 Purpose of this continuing research is to define the fertility requirements and to improve soil test calibration for tomatoes. Three experiments were conducted in 1971. Cooperating growers were Billy Adkison, James Bedsole, Jr., and Leon Keel. Four experiments were conducted in 1972. These experiments were on the farms of James Bedsole, Jr., H. D. Green, Paul Kelly, and Leon Keel. Each grower prepared the land, layed off rows, subsoiled, cultivated, and sprayed for disease and insect control in the experimental test area just as he did in his tomato field. The researchers applied the fertilizer, planted, and harvested tomatoes from the test area. Each test area was marked off into 24 single-row plots 6 feet wide and 15 feet long and included six treatments replicated four times. Rates of nitrogen (N) from ammonium nitrate were 0, 50, 100, and 160 pounds per acre. Except for one phosphorus (P) "check" treatment that received no P and one potassium (K) "check" treatment that received no K, all plots received 80 pounds P (180 pounds P20 5 ) and 150 pounds K (180 pounds K2 0) per acre. Gypsum and a nematicide were used at recommended rates on all plots. Approximately one-third of the N, all the P, onehalf the K, and all the gypsum were applied before planting. They were applied on a 3-foot strip centered on the row and incorporated with the soil using a rototiller. The remaining N and K were sidedressed about 6 to 7 weeks after transplanting when A COOPERATIVE RESEARCH PROGRAM 1 Associate Professor, Department of Agronomy and Soils; Assistant Professor, Department of Horticulture; and Research Associate, Department of Agronomy and Soils. 2 Successful establishment of the research program was made possible through efforts of the Geneva County Extension Chairman. plants were well into the fruit set stage and first fruit were about one-half mature size. During the harvest period, ripe, pink, and mature green tomatoes were picked once each week. Tomatoes were sorted into three marketable size categories, and culls, and weighed. In reporting relative yields in the tables, treatment four was considered as the reference for 100 per cent yield. In some cases, however, it was not the highest yield as lower N rates produced more marketable tomatoes. INDIVIDUAL EXPERIMENTS-1971 In general 1971 was an unfavorable year for tomatoes and yields were low. Late cold weather with near freezing or light frost on several occasions after planting along-with excessive rain resulted in poor growth of plants. In spite of the low yields, however, the relative results showing the benefit of fertilizer were similar to other years. Adkison farm (Table 1.) Tomatoes at this location were not staked and were not irrigated. There was a large increase in yield from the applied N, P, and K fertilizer. Without N the yield was only 63 per cent; without P the yield was 72 per cent and without K the yield was 73 per cent of top yields for the respective elements. From 50 to 100 pounds of N per acre was adequate for top yields at this location. Most of the benefit from fertilizer appeared to be an increase in the yield of large (size 5 x 6 and larger) size tomatoes. TABLE 1. YIELD OF TOMATOES AT BILLY ADKISON's FARM, 1971 Treatment, lb. /acre K P N No. 1 2 3 4 5 6 0 50 100 160 160 160 80 80 80 80 0 80 150 150 150 150 150 0 Marketable fruit per acre & larger 5x6 Lb. 6x6 Lb. 3,037 4,296 4,465 4,368 3,303 3,860 6x7 Lb. 3,086 2,868 3,400 4,102 2,311 2,856 Total Relative yield 63 91 99 100 72 73 Lb. 12,064 17,363 18,900 19,045 13,746 13,818 r Pct. E 5,941 10,200 11,035 10,575 8,131 7,102 Soil test P -"medium"; Variety, Homestead. soil test K = "high." Bedsole farm (Table 2). Even though tomato yields were very low, the results show the benefit from applied fertilizer. Without N the yield was only 32 per cent; without P the yield was 82 per cent; and without K the yield was only 62 per cent of top yields. TABLE 2. YIELD OF TOMATOES AT JAMES BEDSOLE'S FARM, TABLE 4. YIELD OF TOMATOES AT BEDSOLE'S FARM, 1972 Treatment, lb./acre K P N No. 1971 Treatment, lb. /acre Marketable fruit per acre 1 2 3 4 5 6 0 50 100 160 160 160 80 80 80 80 0 80 150 150 150 150 150 0 Marketable fruit 6 x 6 6 x7 5x 6 &larger Lb. Lb. Lb. 6,620 8,160 8,160 10,240 8,170 11,260 9,430 8,200 12,210 9,740 8,580 11,830 3,530 4,420 5,900 7,830 8,230 9,780 per acre Total Relative yield Pct. Lb. 22,930 76 29,670 98 29,800 99 30,160 100 13,850 46 25,850 86 No. N 0 50 100 160 160 160 P 80 80 80 0 80 K 150 150 150 150 150 0 x 6er &largera Lb. 133 912 1,343 1,209 641 508 6x6 Lb. 314 1,748 1,779 1,464 871 859 Total Relative yield Pct. Lb. Lb. 32 1,283- 1,730 2,870 6,074 101 2,952 5,530 111 2,819 5,492 100 82 2,964 4,477 62 2,062 3,429 6 x7 "medium." Soil test P - "medium"; soil test K - "high." Variety, Floradel. Soil test P "medium"; soil test K- Variety, Floradel. Keel farm (Table 3). Tomatoes at this location were irrigated, yet yields were still low, apparently as a result of the unfavorably cold weather during the early part of the growing season. Before planting about 300 pounds of 15-15-15 fertilizer was apTABLE not receive P fertilizer being only 46 per cent of maximum. Without K fertilizer the yield was 86 per cent of maximum. Green farm (Table 5). Yields of marketable tomatoes ranged from about 8,500 pounds to about 20,000 pounds at this location. Yield was more than doubled by N fertilizer with the highest yield resulting from application of 100 pounds of N. The yields from both 50 and 160 pounds of N were lower and were similar to each other. Without P fertilizer the yield was 75 per cent of maximum and without K fertilizer was 89 per cent of maximum. TABLE 3. YIELD OF TOMATOES AT LEON KEEL'S FARM, 1971 5. YIELD OF TOMATOES AT GREEN'S FARM, 1972 No. 5 160 6 Treatment, lb./acre Marketable fruit per acre N P 80 80 150 0 150 3,715 4,780 4,465 3,073 3,545 28698 4,622 3,812 3,848 11,410 12,136 11,011 104 110 100 4 160 160 80 I I~I~ r "high"; soil test K Soil test P Variety, Floradel. "high." 1 2 3 4 5 6 0 50 100 160 160 160 80 80 80 80 0 80 5 6er &larger Lb. 150 2,920 150 6,110 8,120 150 150 6,470 150 4,140 0 5,870 K 6 x6 Lb. 2,230 5,290 5,390 5,090 3,590 5,030 6 x7 Lb. 3,410 5,320 6,460 5,380 5,030 4,200 Total Relative yield Pct. Lb. 8,550 50 16,730 99 19,970 118 16,940 100 75 12,760 89 15,110 Soil test P - "high"; soil test K Variety, Floradel. "medium." plied broadcast to all of the area. This probably was adequate for tomatoes on this soil as no yield difference was obtained from the additional fertilizer treatment applied to the plots. Generally, yields would not be increased by added P and K fertilizer on soils testing this high in these elements. INDIVIDUAL EXPERIMENTS-1972 Tomatoes in all the experiments in 1972 were staked and at the Keel farm supplemental irrigation was used. In general, weather conditions were favorable and yields were higher than in 1971. The Floradel variety was used in three of the experiments and Homestead in one. Bedsole farm (Table 4). Yields ranged from a low of about 14,000 pounds to a high of about 30,000 pounds per acre. Without N fertilizer the yield was 76 per cent of maximum. Yields were about the same for the three rates of 50, 100, and 160 pounds N per acre. Lowest yield was from the treatment that did Kelly farm (Table 6). The variety Homestead was used at this location. Yields ranged from about 18,000 to 24,000 pounds of marketable tomatoes. Without N fertilizer the yield was 80 per cent of maximum. Each of the other three rates of N (50, 100, and 160 pounds per acre) resulted in about the same yields. Without P fertilizer the yield was 93 per cent of maximum. Leaving K fertilizer off at this location made little or no difference in the yield. TABLE 6. YIELD OF TOMATOES AT KELLY'S FARM, 1972 Treatment, lb./acre K N P No. 5 xer 6 x 6 Lb. 7,570 10,310 8,760 Marketable fruit per acre 6 x 7 Total Relative Lb. 4,190 5,660 5,540 Lb. 6,380 6,670 6,720 Lb. 18,140 22,630 21,020 Pct. 80 100 93 1 4 5 0 160 160 80 80 0 150 150 150 "low"; soil test K - "medium." Soil test P Variety, Homestead. Keel farm (Table 7). Harvest of plots was discontinued at this location when about one-half of the tomatoes had been picked; therefore, yields do not include the last part of the harvest season. The yield of marketable tomatoes ranged from about 12,000 to over 17,000 pounds. Without N fertilizer the yield was about 78 per cent of maximum. Lowest yield, 70 per cent of maximum, was from the treatment receiving no P fertilizer. Without K fertilizer the yield was 92 per cent of maximum. TABLE 7. YIELD OF TOMATOES ATKEEL'S FARM, The results showed that yields without P fertilizer were generally only about 70 to 90 per cent of maximum with yield at one location being only 46 per cent. Without K fertilizer the yields were generally about 85 to 90 per cent of maximum and one soil "low" in soil test K yielded only 62 per cent. These results show the importance of applying fertilizer P and K for tomatoes on these soils. The benefit from nitrogen fertilizer varied from one farm to another but generally 50 to 100 pounds N per acre resulted in maximum yields. Tomatoes are grown in rotation following corn, peanuts or some other well fertilized crop; thus, the value of residual or carryover of fertilizer N from the previous crop or of legume N from peanuts might influence the response of tomatoes to applied N. In most cases the yields for 50, 100, and 160 pounds added N were similar indicating that the grower has a relatively wide range for N fertilization and may safely apply up to 160 pounds without reducing yields. Experiments with higher rates of N at other locations in the State indicate that yields may be reduced by N rates of 180 pounds or more. Also there has been no evidence of a reduction in quality of tomatoes, including storage life and firmness, from rates of N up to 180 pounds per acre. 1972 Treatment, lb. /acre No. N P K Marketable fruit per acre &larger 6 x 6 6 x 7 Total RelatiVed Lb. 4,860 6,620 6,320 6,240 4,910 6,040 Lb. Lb. 4,480 4,270 5,060 4,550 3,980 5,300 6,170 4,990 3,680 3,550 4,560 5,330 medium." Lb. 13,610 16,230 15,600 17,400 12,140 15,930 Pct. 78 93 90 100 70 92 1 2 3 4 5 6 0 50 100 160 160 160 80 80 80 80 0 80 150 150 150 150 150 0 Soil test P "low"; soil test K Variety, Floradel. SUMMARY Test areas were located on growers fields with most of them on "low" or "medium" P or K soils.