【摘要】 以土垫旱耕人为土为供试土壤,采用大田试验,研究了半湿润农田两种杂草处理方式下(成熟后期清除杂草-A区和苗期开始清除杂草-B区),不同施氮量对夏玉米产量及氮素利用效率的影响。结果表明,当施氮量为0、45、90、1351、80 kg/hm2时,B区玉米子粒产量比A区分别增加了8.7%、12.1%、9.4%、5.0%和12.5%;吸氮量分别增加了1.5、2.9、4.85、.2和4.3 kg/hm2。A区和B区全生育期0—100 cm土层矿质氮(Nmin)累积量变化趋势基本一致,但B区比A区变幅较大。当施氮量为45、90、135和180 kg/hm2时,B区氮肥利用率、氮肥农学利用率、氮肥生理利用率均高于A区。研究还发现,在A区,当施氮量为180 kg/hm2时,杂草干生物量最大,为1518.3 kg/hm2,不施氮时,杂草的生物量最低,为845.7 kg/hm2;杂草的吸氮量随施氮量的增加而增加。可见,清除玉米农田杂草不仅可以提高作物产量和氮肥利用率,而且在减少氮素损失方面具有一定作用。更多还原

【Abstract】 A field experiment was carried out using loess soil to study the effect of different N rates on grain yield and nitrogen use efficiency as affected by two different weed treatments [weed removed at harvesting stage(Area A) and at seedling stage(Area B)].The result showed that grain yield in Area B increase by 8.7%,12.1%,9.4%,5.0 % and 12.5% than grain yield in Area A for N rates of 0,45,90,135 and 180 kg/ha,respectively.Total N uptake in Area B increased over Area A by 1.5,2.9,4.8,5.2 and 4.3 kg/ha,respectively.Across the whole growing stage,the change trends of organic nitrogen and accumulative mineral nitrogen in Area A and B were similar,however,the range of Nmin change in Area B was higher than Area A.Nitrogen use efficiency(NUE),N agronomic efficiency(NAE) and N physiological efficiency(NPE) in Area B were higher than those in Area A at different N rates.The result also showed that in Area A weed dry matter was largest when N rate was 180 kg/ha,which was 1518.3 kg/ha,and weed dry matter was lowest without N application,which was 845.7 kg/ha.The weed N uptake increased with N rate.Removing weed from field could increase maize grain yield,improve NUE and decrease nitrogen loess.更多还原