Effect of long - term integrated nutrient management on crop yield, nutrition and soil fertility under rice-wheat system

Abstract

Long-term effect of nitrogen substitution (25 to 50%) through different organics, viz., FYM (farm yard ma-nure), GM (green manure) and WS (wheat straw) on crop yield, nutrition and physico-chemical properties of soil was studied under rice-wheat system. The data of long term experiment revealed that maximum grain yield of 46.83 qha-1 in wheat was obtained when 100% RDF applied through mineral fertilizers after 50% N of RDF being substituted with FYM in rice. Grain yield of wheat declined under control and sub-optimal fertilizer inputs (50% or 75% recommended fertilizer NPK), whereas positive yield increment was observed under treatments receiving organic supplements. The analysis of soil samples showed that soil pH reduced from initial value of 7.40 to 7.22, organic carbon build-up from 0.46% to 0.76%, available N from 194.00 to 225.95 kgha-1 available P2O5 from 23.60 to 49.54 kgha-1 and available K2O from 155.00 to 189.95 kgha-1 However, available Sulphur and DTPA-Zn increased from 7.74 to 14.41 kg ha-1 and 0.75 to 1.37 mg kg-1 respectively due to long-term (29 years) integrated nutrient management practices under rice-wheat system in alluvial soil. In conclusion, substitution of 50% and 25% N of RDF to rice through organics either FYM / Green manure / Wheat straw significantly increased the crop yield and nutrient uptake of wheat as well as build up the organic carbon, available N, P2O5, K2O, Sulphur, DTPA extractable Zn, Cu, Fe and Mn of post harvest soil after 29 years of the experiment.