Predicting potential Anaerobic Nitrogen mineralization of rice–rice and rice–wheat soils of Asia uri icon

abstract

  • Nitrogen (N) supplying capacity of soils in rice (Oryza sativa L.)based cropping systems has been reported to be in decline in some sites in Asia. Studying the relationship between N mineralization, rice cropping intensity and soil properties may help us understand changes in N supplying capacity. We conducted short- and longterm laboratory incubations in flooded, anaerobic conditions to measure N mineralization in a range of rice-rice and rice-wheat (Triticum aestivum L.) cropped soils. Our objectives were to determine: (1) what soil properties affect potential anaerobic N mineralization, and (2) whether potential anaerobic N mineralization is affected by rice cropping system. Several soil properties, especially total organic N (TON) and total organic C (TOC), were Positively correlated with N mineralization potential at 30 degreesC (N(0)) and with 7-d production of NH(4) at 40 degreesC (N-7-d). Nitrogen mineralization was only weakly correlated with TON or TOC if the initial large flush during the first 14 d was ignored. Rice-rice soils on average had greater N mineralization than rice-wheat soils. mostly due to higher TON concentrations. Seven-day production of NH(4) at 40 degreesC was so similar to N(0) estimated after 84 d of anaerobic incubation at 30 degreesC that the 7-d incubation could possibly substitute for the long-term one in developing N fertilizer recommendations.

publication date

  • 2001
  • 2001
  • 2001