Carbon sequestration and yield of rice (Oryza sativa)–wheat (Triticum aestivum) soils amended with different organic manures and tillage practices

A field experiment was conducted during 2 kharif and rabi seasons during 2006–08 with rice (Oryza sativa L.)– wheat [Triticum aestivum (L.) emend. Fiori & Paol.] cropping system at New Delhi. The main plots comprised 2 tillage treatments, viz. puddled and non-puddled in rice and with tillage and no-tillage in wheat. The subplots included 7 fertilizer treatments including recommended doses of urea (120 kg N/ha), urea + farmyard manure (FYM), urea + green manure (GM), urea + municipal solid waste (MSW) compost. Yields of rice and wheat were higher under puddled/conventional tilled condition compared to non-puddled/no-tillage conditions. Application of organic matter with recommended dose of mineral fertilizer gave the highest grain and straw yields compared to other treatments. The carbon sequestration potential was 0.146, 1.31, 1.165, 1.238, 0.728, 1.019 and 0.874 tonne C/ha under 120 kg N, 120 kg N + 6 tonnes FYM, 60 kg N + 6 tonnes FYM, 120 kg N+ 3 tonnes GM, 60 kg N + 3 tonnes GM, 120 kg N + 60 kg N (MSW compost) and 120 kg N + 60 kg N (MSW compost) treatments respectively, under puddle/tilled rice–wheat cropping system. However, under non-puddled/no-tilled crops carbon sequestration potential were 0.291, 1.601, 1.456, 1.529, 1.019, 1.31 and 1.048 tonnes C/ha under treatment having 120 kg N, 120 kg N + 6 tonnes FYM, 60 kg N + 6 tonnes FYM, 120 kg N+ 3 tonnes GM, 60 kg N + 3 tonnes GM, 120 kg N + 60 kg N (MSW compost) and 120 kg N + 60 kg N (MSW compost) respectively. The addition of organic manures resulted in sequestration of carbon in rice–wheat cropping system. The carbon sequestration increased under reduced tillage conditions of soil.