Influence of long-term integrated nutrient management on productivity and soil properties in rice (Oryza sativa)rice cropping system in an acidic soil

Abstract

A permanent plot experiment on integrated nutrient supply system with 12 treatments replicated thrice in rice (Oryza sativa L.)rice cropping system was conducted during 198384 to 201314 at Chiplima in a sandy loam soil. The soil had pH 5.4 and organic carbon 0.62%. Application of 50% recommended dose of nutrients through chemical fertilizers (RDF, i.e. N:P:K @ 100-22-41.3 kg/ha) coupled with 50% recommended N through green ma- nuring of Sesbania cannabina to the rainy season (kharif) rice followed by supply of 100% RDF through chemical fertilizers to summer rice resulted in higher average (of 31 years) system yield of 9.32 t/ha/year. This treatment combination increased average system yield by 7, 25 and 122% over application of RDF, farmers practice (N:P:K @ 50-11-20.7 kg/ha + 2 t FYM/ha for both crops) and control (without application of any fertilizer) respectively. This treatment also recorded the highest system gross returns ( 115,030/ha), net returns ( 59,284/ha) and ben- efit: cost ratio (2.06). Application of 50% RDF through fertilizers coupled with 50% recommended N through FYM to kharif rice followed by supply of 100% RDF through chemical fertilizers to summer rice was the second best treatment combination with system grain yield 9.21 t/ha/year, system gross returns ( 113,520) and net returns ( 54,874/ha). These were also most sustainable and improved soil physico-chemical properties with respect to bulk density, soil organic carbon, available NPK, microbial biomass carbon and soil nutrient balance.