Effect of Silkworm Pupae Compost on Soil N mineralization, Nutrient Uptake, Crop Yield and Plant Nutrient Contents of French Bean ( Phaseolus vulgaris L.)

Abstract

A field experiment was conducted during the period of December 2007 to March 2008 on a sandy clay loam soil in Bangalore, India to study the effect of silkworm pupae compost as a nutrient source for French bean. Four different mixtures of seri-compost were prepared using raw pupae wastes of silkworm and evaluated for soil N mineralization, plant nutrient content, nutrient uptake and yield of French bean. Soil incubation and a field experiment was conducted using 11 treatment combinations containing different ratios of inorganic fertilizers, farm yard manure and seri-compost. The NH4+-N release in soil increased rapidly up to 28 days after incubation (DAI) and thereafter, it decreased. At 0-28 days after incubation, the highest increase in NH4+-N was recorded in treatment 8 (T8) which contained 50% N RDF (Recommended dose of fertilizer) +50% N seri-compost 3(C3) prepared with silkworm pupae waste and 10% cowdung slurry (5.6 to 92.2 mg kg-1). The lowest increase was in treatment 5 (T5) in which 100% N supplied through Seri-compost 4 (C4) prepared with silkworm pupae waste with 10% cow dung slurry, 5% rock phosphate and microbial inoculant (14 to 28 mg kg-1). At 0-21 days after incubation, the highest increase in NO3--N release was recorded in treatment 2 (T2); 100% N through seri-compost 1 (C1) prepared with silk worm pupae waste and farm yard manure (16.8 to 112 mg kg-11) and lowest in treatment 4 (T4); 100% N through seri-compost 3 (C3) (50.4 to 92 mg kg-1). The NO3--N release in soil increased rapidly up to 21 DAI and thereafter it decreased. All the silkworm pupae compost treatments incorporated with 50% N RDF improved yield and highest bean yield of 5793 kg ha-1 was in treatment 7 (T7) which contained 50% N RDF+50% N Seri-compost 2. The highest N, P and K content of French bean plants at maturity was noticed in T6 (50% N RDF+50% N silkworm pupae compost 1), T7 (50% N RDF+50% N seri-compost 2) and T3 (100%N through Seri-compost 2) treatments respectively. Application of seri-compost increased available N, P2O5 and K2O status of the postharvest soil. Highest N, P and K uptake was recorded from 50% N RDF with seri-compost 2 (T3), seri-compost 3 (T8) and 100% N through seri-compost 3 (T4) respectively. Therefore seri-compost could be used to obtain higher yields of French bean than the recommended package of practices with inorganic fertilizer.