Evaluation of crop residue management practices for improving yields, nutrient balance and soil health under intensive rice-rice system

Field experiments were conducted during 1998 - 2000 on a sandy clay loam soil (Deep Aquic Ustorthent) to evaluate the influence of different crop residue management practices on rice yields, nutrient balance and soil health/quality indicators. Incorporation of 100 and 50% paddy straw in both seasons, incorporation of 100% straw+green manure, GM (in situ grown Sesbania aculeata) in kharif season and 100% straw burning in both seasons were compared with a control (straw removal). Significant improvement in rice productivity was observed with recycling of 100% straw directly or its ash or straw+GM over straw removal or 50% straw addition after two crop cycles. Recycling of crop residues substantially improved partial N balance in the system by 123, 33 and 24% with 100% straw+GM, 100 and 50% straw, respectively over straw removal or burning indicating nutrient addition to soil reserves. Partial K balance was positive with crop residue treatments and negative when straw was removed (−107 kg ha ⁻¹). A decrease in bulk density and increase in infiltration rate was observed by crop residue incorporation over control or straw burning. Available K increased significantly with incorporation of straw or its ash (440–519 kg ha⁻¹) over control (377 kg ha⁻¹) with no significant change in available N and P. Soil organic carbon (SOC) content and soil respiration rate increased significantly in all the crop residue treatments over control with maximum values in straw+GM treatment. Thus, incorporation of paddy straw alone or in combination with green manure improved yields, nutrient balance and soil health under intensive rice mono-cropping conditions.