Recycling of crop wastes and green manure and their impact on yield and nutrient uptake of wetland rice

The potential for using crop wastes as a source of nutrients on the yields of rice grown under submerged conditions was studied in both field and pot experiments at the Experimental Farm of the Agricultural and Food Engineering Department, Indian Institute of Technology, Kharagpur during 1992/93 and 1993/94. The application of groundnut haulm at 3 0 t/ha, maize stover at 5.0 t/ha, mustard stover at 3.0 t/ha and green manure at 1.5 t/ha contributed considerable amounts of nutrients, which improved components of yield, yield and nutrient uptake by rice and also improved the organic carbon (OC)content and available N, P and K in the soil. Yields and soil fertility were both further improved when these organic materials were combined with inorganic fertilizer to supply the recommended amounts of nutrients, except that inorganic fertilizer alone did not cause an increase in the OC content of the soil. In the pot experiment, the production of NH4-N and NO3-N was both larger and more consistent when organic and inorganic nutrient sources were added together than when inorganic sources alone were used.