通过田间定位试验研究秸秆覆盖条件下施氮量对小麦氮素吸收利用及土壤硝态氮残留的影响。试验包括覆盖(不覆盖和秸秆覆盖4500 kg/hm^2)和施氮量(0,75,150,225和300 kg N/hm^2)两个因素,共10个处理,重复3次。3年结果表明:秸秆覆盖对冬小麦吸氮量没有显著影响,但在偏旱年份,秸秆覆盖有利于提高氮肥利用效率。与不覆盖类似,秸秆覆盖冬小麦吸氮量在3年间呈持续增加趋势。不论秸秆覆盖还是不覆盖,施氮量小于等于150 kg/hm2时,对土壤硝态氮残留量均没有显著影响;施氮量高于150 kg/hm^2时,土壤残留硝态氮量则显著增加,0-200 cm剖面出现明显的累积峰,秸秆覆盖土壤残留硝态氮累积峰较不覆盖处理深40 cm左右。
A 3-year-long field experiment was carried out to investigate the effects of nitrogen rate on nitrogen uptake and utilization of winter wheat and residual nitrate in soil under straw mulch.The experiment,including mulch(no mulch and straw mulch 4 500 kg/hm^2)and N rate(0,75,150,225 and 300 kg N/hm^2),had 10 treatments with 3 replicates.The results showed that there was no significant difference of N uptake by winter wheat between straw mulch and no mulch treatments.However,in the drier year,straw mulch could improve N use efficiency.No matter with straw mulch or no mulch,N uptake by winter wheat increased during 3 years.For both straw mulch and no mulch treatments,accumulated nitrate in soil didn't increase significantly when N rate increased from 0 to 150 kg/hm^2,while accumulated nitrate peak was found throughout the soil profile when more than 150 kg/hm^2 nitrogen fertilizer was applied.The accumulated nitrate peak of straw mulch treatment appeared at the soil depth 40cm deeper than that of no mulch.