Composts from various municipal solid waste feedstocks affect vegetable crops. II. Growth, yields, and fruit quality

Abstract

Compost (biosolids and yard trimmings at 134 t · ha-1) was applied to a sandy field soil with fertilizer at 0%, 50%, or 100% of the grower's standard rate (71N-39P-44K kg·ha-1) broadcast and 283N-278K kg· ha-1 banded in bed centers). Raised beds were constructed and covered with polyethylene mulch. and 'Elisa' bell peppers (Capsicum annuum L.) were transplanted into the plots. Foliage, samples taken at early harvest indicated that leaf N concentrations increased and Cu concentrations decreased with increasing fertilizer rates. Leaf concentrations of P, K, Ca, and Mg increased and Cu decreased in plots amended with compost. Marketable pepper yields from plants grown in plots amended with compost were 30.3, 35.7, and 31.1 t·ha-1 in plots with 0 %, 50 %; and 100 % fertilizer rate, respectively. Without compost, yields were 19.8, 31.1, and 32.0 t·ha-1 with 0%, 50%, and 100% fertilizer rate. 'Valient' cucumbers (Cucumis sativus L.) were seeded through the same polyethylene mulch into the previous pepper plots. Marketable cucumber yields were not affected by residual fertilizer, but were higher (26.8 t· ha-1) in plots amended wit h compost than without compost (22.7 t· ha-1). In a second experiment, a biosolids-yard trimming-mixed waste paper (MWP) compost and a biosolids-yard trimming-refuse-derived fuel (RDF) compost were applied at 0 or 134 t·ha-1 with fertilizer at 0%, 50%, or 100% fertilizer rates, respectively. With no fertilizer, total yields from pepper plants were higher in plots amended with composts than without composts. In 50% fertilizer plots, yields were similar between compost treatments. At 100% fertilizer rate, yields with MWP compost were significantly higher than yields with RDF compost or with no compost. In plots without fertilizer or with 50% fertilizer rates, mean fruit size (g/fruit)was largest with MWP compost, intermediate with RDF compost, and smallest without compost. With 100% fertilizer, mean fruit size was larger with either compost than without compost. Composts combined with low rates of fertilizer generally produced higher pepper yields than other treatments. Residual compost increased yields of a subsequent cucumber crop. Yields from pepper plants without fertilizer were higher when soil was amended with composts with added MWP or RDF, but, with fertilizer, yields were similar or only slightly increased.