摘要： 冬小麦从越冬前到次年春天拔节期,0～90cm土层的土壤N-min变化规律是:土壤N-min在返青初期累积达高峰,且主要分布于0～60cm(占3/4).因此通过测定土壤有效氮的丰缺指导冬小麦春季追氮,最适宜的取土时间是小麦返青初,适宜的取土深度是0～60cm.小麦返青初0～60cm土层土壤N-min测定值与小麦春季最佳追氮量间具有良好的相关性,r=-0.8401(n=11).而可用于土壤N-min简化测定的改进康维皿法土壤有效氮测定值与小麦春季最佳追氮量间的相关性更好.小麦返青初0～60cm土层改进康维皿法土壤碱解氮与小麦春季最佳追氮量间相关系数为γ=-0.8935(n=20),且后者远比前者简便易行,更适合我国国情.在亩产350～400公斤小麦籽粒的产量水平下,最佳追氮量与土测值间的直线关系式为N_f=15.96-0.7766N_改(Nkg/亩).

关键词: 改进康维皿法, 土壤有效氮, 冬小麦, 春季追氮

Abstract: From the period before over-wintering to the period of stem alongation of the next spring, soil N-min in the 0 -90cm depth of the winter wheat fields changed as follows: Soil N-min reached the peak value, and 3/4 in the 0-60cm depth when winter wheat broke dormancy. Therefore the most suitable time for sampling soil should be the dormancy-breaking period, and the sampling depth should be 0 - 60cm for the recommendation of nitrogen fertilizer application for. winter wheat in spring. With this sampling method, the correlation between the soil N-min and the economic optimum amount of topdressing N was r= - 0.8401**(n= 11). However, the correlation between the economic optimum amount of topdressing N and the soil available N determined with the modified Conway method was r= -0.8935**. The latter was better and simpler than the N-min method. It is more suitable to the conditions in China. At the yield level, of 5250-6000kg / ha, the equation comprising the optimum amount of topdressing N and the soil available N determined by the modified Conway method was Nf = 239.4- 0.7766 (soil N) (unit: N kg/ha) .

Key words: Modified Conway method, Soil available nitrogen, Topdressing for winter wheat in spring