Effect of organic fertilizer applications on growth, yield and pests of vegetable crops

Dan O. Chellemi, George Lazarovits

Abstract


Field experiments were conducted to measure the yield response of Cantaloupe (Cucumis melo), pepper (Capsicum annuum), and tomato (Lycopersicon esculentum) to an organic fertilizer derived from hydrolyzed feather, meat, bone, and blood meal, sulfate of potash and langeinite (Nature Safe 10-2- 8). The effects on soilborne pests, soil nutrient concentrations, and soil microorganism populations were also determined. The field site had been previously cropped to tomato using conventional production practices and was judged to have low soil fertility. Application of 560 N, 110 P, 440 K (kg·ha[sup-]) resulted in an increase in soil pH, ammonia concentrations and counts of total soil fungi, but not total soil bacteria. Based on observations of growth, necrosis and mortality an application rate of 440 N, 88 P, 352 K (kg·ha[sup-]) was phytotoxic to pepper. Phytotoxicity on tomato was observed at an application rate of 1120 N, 220 P, 880 K (kg·ha[sup-]). A quadratic effect of application rate was observed for yield of pepper (r= 0.83) and tomato (r= 0.98). Optimum yields were projected to occur at 310 N, 62 P, 248 K (kg·ha[sup-) for pepper and 400 N, 80 P, 320 K kg·ha[sup-] for tomato. A second location that had been previously cropped to vegetables under certified organic production guidelines and had moderate levels of soil fertility, was used to test the effect on cantaloupe yields. An application rate of 110 N, 22 P, 88 K (kg·ha[sup-]) of Nature Safe increased early yields as compared to a formulation of dried poultry manure (NOPI 5-4-5) applied at 112 N, 90 P, 112 K (kg·ha[sup-]) or an unfertilized control. However, final total yields of cantaloupe were similar among the three treatments. The effect of fertilizer rates on emergence of yellow (Cyperus esculuntus) and purple nutsedge (C. rotundus) was erratic with suppression observed at rates phytotoxic to pepper. Reductions in the incidence of southern blight, caused by Sclerotium rolfsii, occurred on tomato and pepper at application rates below the rates required for optimum yields. This study demonstrates that organic fertilizers can provide multiple benefits for Florida vegetable production systems including improving fertility, increasing soil microbial populations, and reducing the incidence of a soilborne disease.

Keywords


cantaloupe; organic agriculture; pepper; purple nutsedge; sclerotium rolfsii; soil quality; tomato; yellow nutsedge

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Proc. Fla. State Hort. Soc.     ISSN 0886-7283