Effects of green manure and compost of pea plant on wheat
Cereal based cropping systems have been established for food security in many countries where farmers use plenty of chemical fertilizers, but adoption of leguminous crop in the system is not popular. Excessive use of fertilizers is responsible for health and environmental hazards. Adoption of legume in cereal based cropping systems and improvement of organic fertilizer are needed to reduce chemical fertilizer use. Pot experiments in the greenhouse were carried out with green manure (GM) and compost of green pea (Pisum sativum L.) plant residue (PP) with dried chicken manure (CM) and/or rapeseed (Brassica napus L.) oil residue (RR) at Gifu University, Japan during 2004-2007. The goal of the experiments was to assess: the effectiveness of GM and compost on growth and yield of wheat and ii) the efficiency of GM and compost to supply nutrients. After pod harvest, PP was mixed with CM or RR or half of CM plus half of RR, or nothing was mixed with PP for making GM and compost for wheat. Results of two pea-wheat cycles revealed that composts of PP with CM and CM plus RR were enriched by higher microbial activity; maintained the activity at a higher rate in the soil and supplied sufficient nutrients to wheat. As a result, wheat harvested higher amount of N P K with efficient recovery rate, which improved yield components and yield. Apparent nutrient recovery efficiencies of the composts could save fertilizer use and environment. Although higher value was found from compost than GM of similar organic materials, but among the GM treatments, PP with CM plus RR also gave higher yield. Moreover, instead of having enough nutrients, RR can not supply nutrients satisfactorily due to delay release but CM itself is efficient and stimulates RR to release nutrients. Therefore, pea compost with CM or CM plus RR is recommended for wheat.