Effect of organic nutrient sources on yield, nutrient uptake and soil biological properties of rice (Oryza sativa)-based cropping sequence

A field experiment was carried out at Varanasi for two years (2005–2007) to study the effect of organic nutrient sources on yield, nutrient uptake and soil properties of rice (Oryza sativa L.) based cropping sequence. Seven rice–based cropping sequences viz. rice–potato (Solanum tuberosum L.)–onion (Allium cepa L.); rice–green pea (Pisum sativum var. hortense)–onion; rice – potato–cowpea (Vigna unguiculata subsp. sesquipedalis); rice–green pea–cowpea; rice–rajmash (Phaseolus vulgaris L.)–onion; rice–rajmash–cowpea and rice–maize (Zea mays L.)– cowpea were assigned to main plots and three treatments of nitrogen application viz. control; organic manure; organic manure + biofertilizer were allotted to sub plots. Highest rice equivalent yield (35.57 t/ha), monetary net returns ( 268.7×10³/ha), production efficiency (96.81 and 98.11 kg/ha/day) and irrigation efficiency (504.8 and 511.6 kg/ha-cm) were found under rice–potato–onion cropping sequence. Among the organic treatments, the highest rice equivalent yield (35.3 t/ha), production efficiency (95.7 and 97.8 kg/ha/day), irrigation efficiency (515.7 and 527.4 kg/ha-cm) and soil biological indictors like dehydrogenase activities, urease activities, soil microbial biomass carbon and soil microbial biomass nitrogen were obtained under organic nutrient management combined with biofertilizers.