太湖地区高产稻田氮肥施用与作物吸收利用的研究

APPLICATION AND CROP RECOVERY OF N-FERTILIZER IN HIGH-YIELDING PADDY FIELDS OF TAIHU REGION

本文讨论长期高量偏施氮素化肥的高产稻田氮肥施用与作物产量、作物对养分吸收利用之间的关系。研究结果表明：化学氮肥施用量（养分量，下同）300kg／ha·yr.,作物增产显著，每公斤氮增产13．5kg粮食，氮素利用率达40．3％，省肥、经济、合理；施用量达450kg／ha·yr.,作物产量增长甚微；施用量达600kg／ha·yr.,每公斤氮只增产7．29kg粮食，氮肥利用率降至17．2％，水稻茎秆中含氮量大幅度增加，空秕率上升，千粒重下降，产量降低。太湖地区高产稻田目前稻麦产量为10-12t／ha水平时，氮素化肥施用量平均控制在375kg／ha·yr。左右为宜。与大面积生产相比，可节省氮肥20—30％。

Currently, in the Taihregion, the application of N fertilizer in the high-yieding paddy fields of ricewheat double cropping system averages around 520kg N per hectare per year.Experiments for years shewed that N fertilization at a rate of 300kg N per hectare per year increased the crop yield significantly by 13.5kg of grain per kg of N applied, with the N recovery rate reaching 40.3%; but the increase was not significant at a rate of 450kg N, and 7.29kg of grain was increased by per kg of N applied with the N recovery rate dropping to 17.2% at a rate of 600kg N per hectare per year.In the last case, the N content in rice straws and sterility grain rate went up while the thousand-grain weight and the yield declined. Consequently, at the current yield level of 10-12 ton per hectare on the high yielding paddy field, the N fertilization rate was recommended to be at 375kg N per hectare per year, which could save 20-30% N-fertilizer as compared with the rate for large-area production.