Relative efficiency of diammonium phosphate and mussoorie rock phosphate on productivity and phosphorus balance in a rice–rapeseed–mungbean cropping system

Abstract

The field experiments were conducted at the Indian Agricultural Research Institute, New Delhi, India for 3 years from 2001–2002 to 2003–2004 to study the relative efficiency of diammonium phosphate (DAP) and Mussoorie rock phosphate along with phosphorus solubilizing bacteria inoculation (MRP + PSB) at different rates of application on productivity and phosphorus balance in a rice-rapeseed-mungbean cropping system. Phosphorus application significantly increased the productivity of rice-rapeseed-mungbean cropping system and resulted in an increase in 0.5 M NaHCO3 extractable P content in soil. The relative agronomic effectiveness (RAE) of MRP + PSB in relation to DAP as judged by the total productivity was 53–65% in the first cycle but reached 69–106% in the third cycle of the cropping system. The P balance (application—crop removal) was generally more positive for MRP + PSB than DAP and the highest P balance was recorded with an application of 52.5 kg P ha−1 as MRP + PSB, resulted in highest 0.5 M NaHCO3 extractable P content in soil. The present study, thus, shows that MRP + PSB could be usefully employed as an alternative to DAP in long term in the rice–rapeseed–mungbean cropping system.