Large amounts of N fertilizer are applied annually to cropland because N is the most limiting nutrient for crop production.  Therefore, N leaching into groundwater and N₂O emission could have major environmental implications on water quality and global warming.  In general, agricultural practices contribute about 70% of global N₂O emissions. This session will address management practices, such as types and rates N fertilization, cover crop, crop rotation, tillage, etc. that enhance crop N-use efficiency, reduce N losses through emission or leaching, and maintain crop yields.