Balance sheet of nitrogen and phosphorus as influenced by integrated phosphorus management in soybean-wheat cropping system in Southern Rajasthan.

摘要

Field trials were conducted during 1999-2000 and 2000-01 in Udaipur, Rajasthan, India, to workout the balance sheet of nitrogen and phosphorus in soyabean-wheat cropping system under the influence of phosphorus (sources and levels), farmyard manure (FYM) and phosphate solubilizing bacteria (PSB) application. Phosphorus fertilizer application through either source (urea phosphate + single superphosphate (SSP) and SSP) and increasing levels (30, 60 and 90 kg P2O5/ha) to soyabean increased the N status of soil at the end of the cropping system, while a slight decrease in soil P content was recorded. The gains in nitrogen fertility due to increasing levels of phosphorus ranged between 8.7 and 13.7 kg N/ha. Although P application up to 90 kg P2O5/ha to soyabean could not maintain the initial P status of soil up to the end of the system but the magnitude of depletion decreased over higher levels. Application of FYM at 10 tonnes/ha (with and without PSB) improved the N status of the soil but the P status at the end of system was less over initial status. Application of 60 kg P2O5/ha to the succeeding wheat crop maintained the soil P status up to the end of cropping system. Thus, for maintaining proper soil health P fertilizer application to both the crops was required.