Predicting potential Anaerobic Nitrogen mineralization of rice-rice and rice-wheat soils of Asia

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 long-term 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°C (N0) and with 7-d production of NH4 at 40°C (N-7-d). Nitrogen mineralization was only weakly correlated with TON or TOC if the initial large flush during the first 14 d was ignore...