前言合理施用氮肥是棉花增产的一个重要关键。随着国家化肥工业的迅速发展,氮肥产量的增长,其用量也随之增多。但从现有的资料分析,氮肥利用率还不高。因此,研究如何提高氮肥的有效利用率和合理施用氮肥,对促进棉花生产具有十分重要意义。本 Preface The rational application of nitrogen fertilizer is an important key to cotton yield. With the rapid development of national fertilizer industry, the increase of nitrogenous fertilizer production also increases. However, from the available data analysis, nitrogen utilization rate is not high. Therefore, to study how to improve the effective utilization of nitrogen fertilizer and rational use of nitrogen fertilizer is very important to promote the cotton production. this