Effect of phosphorus management on production and phosphorus balance in a rice (Oriza sativa L.)-wheat (Triticum aestivum) cropping system

摘要

The present study was carried out at the Indian Agricultural Research Institute, New Delhi, for three crop years (2000-2001 to 2003-2004) to find out the effect of rates and sources of phosphorus on production and phosphorus balance in a rice-wheat system. Phosphorus application significantly increased productivity and P uptake of rice-wheat cropping system and resulted in an increase in extractable P (0.5 M NaHCO₃) content in soil. Mussoorie rock phosphate with phosphorus solubilizing bacteria inoculation (MRP + PSB) at 35 and 52.5 kg P ha−1 was similar to 17.5 and 35 kg P ha−1, respectively, as diammonium phosphate (DAP) in terms of productivity and P uptake of rice-wheat cropping system but significantly superior in terms of PSB population and CO₂ evolution in soil. The P balance was generally more positive for MRP + PSB than for DAP and the highest P balance was observed with the application of 52.5 kg P ha−1 as MRP + PSB. At the end of three cycles of rice-wheat cropping system,net change in extractable P content in soil increased with increasing rate of P application and was highest with the application of 52.5 kg P ha−1 asMRP + PSB to each crop of every year of the three years of study. The present study, thus, indicates that P requirement of a rice-wheat cropping system can be met with 35-52 kg P ha−1 as MRP to each crop with PSB inoculation.