半干旱地区春小麦氮肥后效的研究

连续4年春小麦氮肥后效的大田试验结果表明:在连续2年(2003~2004年)施用纯氮52.5、105、157.5、210 kg/hm2后再连续2年(2005~2006年)停施氮肥,前2年未被利用的氮素可使后2年籽粒平均增产25.4%;干物质在五叶期及以后时期与对照相比均有明显增加;植株吸氮量在后续第1年(2005年)各处理平均增加22.4%,第2年(2006年)各处理平均增加14.0%;氮肥4年累计利用率比4年连续施用氮肥的处理提高了7.8%~12.9%.

Study on the residual effect of nitrogen fertilizer in spring wheat cultivation in semiarid areas

A field experiment of spring wheat cultivation for 4 years was used to study the after-effects of nitrogen fertilizers.The results showed that only a part of nitrogen fertilizers was taken up and used by the seasonal crop,while a large portion of it which was not taken up by crops left in the soil after harvesting.The residual nitrogen in the soil had evident effect on the following crops.However,the residual effects of nitrogen fertilizers on wheat yield would become not evident along with the prolonging of cultivation year,and moreover,the differentiation of the yield was related the annual precipitation pattern.In case of successively applying nitrogen fertilizers with the quota of 52.5 kg/hm2,105 kg/hm2,157.5 kg/hm2 and 210 kg/hm2 at the first two years(2003～2004) and then stopping nitrogen fertilization at the following two years(2005～2006),the unused nitrogen had produced a significant after-effects on the yields in the following two years and increased the yield by 25.4 % on average,increasing the dry matter by higher ratio in the five leave period and the following stages.The plant absorption quantity of nitrogen increased by 22.4 % and 14.0 % respectively on average in 2005 and 2006.Compared with the treatments of successively applying nitrogen fertilizer for four years,the accumulated utilizing rate of nitrogen in four years increased 7.8 to 12.9 %.