Nitrogen losses in rice soils

A review of the literature on nitrogen losses in rice soils due to denitrification, ammonia volatilization, leaching and surface runoff, fixation by minerals and organic matter and immobilisation by micro-organisms is presented. The need to quantify nitrogen losses using 15N-labelled fertilizers in field experiments is suggested. The prospects of improving the efficiency of fertilizer nitrogen by split applications and placement of fertilizers, and by the use of slow release materials, nitrification inhibitors and urease inhibitors, are briefly discussed