稻田施用氮肥,由于硝化和反硝化作用交替进行,引起脱氮损失或淋失,氮素利用率很低。一些稻田氮素平衡研究指出,水稻对氮肥的利用率为20—62%,平均35%;土壤中残留3—21%,平均12%;损失31—61%,平均52%[1]。可见稻田中氮素损失相当严重。采用深层施肥和分期施肥等措施,对于提高氮肥利用 Nitrogen fertilizer applied to paddy field, due to nitrification and denitrification alternately, causing loss or leaching of nitrogen loss, nitrogen utilization is very low. Some paddy field nitrogen balance studies have shown that rice utilization of nitrogen fertilization is 20-62%, an average of 35%; soil residues 3-21%, an average of 12%; loss of 31-61%, an average of 52% [1]. It can be seen that the nitrogen loss in paddy fields is quite serious. The use of deep fertilization and staged fertilization and other measures to improve nitrogen use