Effect of integrated nutrient management on a Typic Haplaquant on yield and nutrient availability in a rice-wheat cropping system

A field experiment was conducted at Mithapur Farm, Patna Campus of the Rajendra Agricultural University, Bihar, India, with rice (cv. Mahsoori) and wheat (cv. UP 262) during 1992-96 in order to assess the integrated effect of chemical fertilizer (NPK) with farmyard manure (FYM) and blue-green algae (BGA) on grain yield and nutrient availability on a Typic Haplaquant. Both rice and wheat yields continued to increase significantly with increasing NPK level up to 100% of the recommended rate. However, maximum yields of rice and wheat were obtained where the recommended rate of NPK was applied along with FYM and BGA. The organic carbon content of the soil decreased up to the rate of 50% of the recommended NPK, either alone or in combination with FYM, BGA, or FYM+BGA. Available soil nutrients were enhanced up to rates of 75% of the recommended NPK dosage, alone or with FYM, BGA, or FYM+BGA, compared with initial values. The maximum build-up of available N, P, and K was measured under integrated use of 100% NPK along with FYM and BGA.