MUNICIPAL SOLID-WASTE COMPOST USE IN TOMATO WATERMELON SUCCESSIONAL CROPPING

Large-scale composting is a relatively new method of municipal solid waste (MSW) disposal in Florida. Addition of organic matter in large quantities to sandy soil can improve water and nutrient retention, and enhance crop production. The objective of this study was to evaluate growth and yield response of a tomato (Lycopersicon esculentum Mill.)/watermelon [Citrullus lanatus (Thunb.) Matsum. & Nakai] successional-cropping system to two MSW compost soil amendments, which were applied to increase soil organic C. Eweson compost (composed of household garbage and wastewater residuals) was added at 13 and 27 MT ha-1, and Earthlife compost (composed of household garbage only) at 75 and 112 MT ha-1 to plots which then received standard, University of Florida-recommended N-P-K fertilizer rates for tomato and watermelon production under micro-irrigation. Two standard-rate fertilizer programs, one including Plant Right(TM) composted chicken manure fertilizer, the other composed of only inorganic and synthetic organic fertilizers, were also included in the study. Irrigation was applied at 0.75, 1.00, and 1.25 times the estimated crop evapotranspiration (ET). Amending soil with Eweson compost resulted in a 16% greater extra-large tomato yield compared to nonamended soil. Amending soil with Earthlife compost produced smaller, N-deficient, lower-yielding tomato plants because it was not fully composted when incorporated. However, the Earthlife matured after 3 months in the soil and increased watermelon yield 54% compared to the non-amended soil. Earthlife produced greater watermelon yields than Eweson, possibly due to the higher rates at which it was applied. Plants treated with composted chicken manure fertilizer yielded equal to those with inorganic fertilizer. Tomato and watermelon yields decreased 20 and 10%, respectively, as irrigation decreased from 1.00 to 0.75 x ET. Composts increased soil water retention and Mehlich-1 extractable Ca, Mg, and P. Improved plant growth and yield in compost-amended sandy soil was most likely due to enhanced physical and chemical properties, especially where compost was applied at 75 MT ha-1 or more.