不同施氮水平和杂草清除时间对半湿润地区农田氮素利用及产量的影响

在半湿润地区中等肥力土垫旱耕人为土上进行田间试验,通过对冬小麦不同生育期杂草和作物样品的采集与分析,研究不同施肥及杂草处理对氮肥肥效的影响。结果表明:作物吸氮量随施氮量增加而增加,杂草吸氮量随吸氮量增加而降低;在不同杂草处理全生育期不清除杂草(A)、越冬前清除杂草(B)、返青期清除杂草(C)和拔节期清除杂草(D)的各个处理中,A、B、C和D杂草吸氮量分别占农田植物(作物 杂草)地上部分总吸氮量的1.98%、1.39%、3.99%和3.82%。籽粒产量随施氮量增加而增加,施氮量为135 kg N.hm-2时产量最高,达5 645.1 kg.hm-2,施氮量高于135 kg N.hm-2时,产量趋于稳定。氮肥利用率、氮肥利用效率、氮肥农学效率和氮肥生理效率均随施氮量增加而降低;从不同杂草处理看,以全生育期不清除杂草处理氮肥利用率最高,达到43.8%,返青期清除杂草处理氮肥利用率最低,为26.3%,二者间差异达显著水平;氮肥利用效率以越冬期清除杂草处理最高,为42.8 kg.kg-1N,全生育期不清除杂草处理最低,为40.6kg.kg-1N;氮肥生理效率以返青期清除杂草处理最高,为57.5 kg.kg-1N,显著高于其他杂草处理。综合氮效率及产量效率,小麦农田杂草处理时间应该相对较早,以越冬期和返青期清除杂草较好。

Effects of Different Fertilizer Application and Time of Removing Weed on the Nitrogen Use and Yield in the Semi-humid of Winter Wheat Field

Application of nitrogen (N) fertilizer is one of the most important measures that increase grain yield and improve grain quality of winter wheat.However,it is common that excessive N fertilizer is applied on fertility field,which not only causes the decline of N use efficiency and economic effects,but also results in larger amount of nitrate-N accumulated in soil,and so it is concerned to bring potential risk environment.In farmland ecological system,N use efficiency may be changed provided that there is weed.Therefore,nitrogen and weed treatments were arranged in a split-plot design with three replicates.Within normal density treatments,five levels of nitrogen,PN₀,PN₄₅,PN₉₀, PN₁₃₅ and PN₁₈₀ were applied.Within each of these treatment combinations,different weed treatments were imposed.The field experiment was conducted in Eum-Orthic Anthrosol located in the semi-humid farmland ecological system.Wheat sample and weed sample were collected at different growth stages of winter wheat,total N of which was measured.The experiment was designed to analyze grain yield and nitrogen utilization under different fertilizer levels and weed treatments.The results indicated that N uptake of crop increased with addition of N fertilize application.N uptake of weed decreased with increase of N fertilizer application during the whole growth stage.Average of N uptake by weed at different treatments A,B,C and D was respectively 2.38,1.60,4.71 and 4.54 kg N·hm^-2,accounting for 1.98%,1.39%,3.99% and 3.82% of the N uptake amount of overground plant.Grain yield increased with addition of N fertilizer application.However,yield with application 135 kg N·hm^-2 amounted to maximum 5 645.1 kg·hm^-2.Nitrogen utilization rate,nitrogen use efficiency and nitrogen agronomy efficiency decreased with an increase of N fertilizer application during whole growth stage of winter wheat.Nitrogen utilization rate of no removing weed treatment at whole growth stage was the highest to 43.8%,and the lowest to 26.3% in removing weed treatment at reviving stage.Nitrogen utilization efficiency of removing weeds at over-winter stage was the highest to 42.8 kg·kg^-1N,and was the lowest to 40.6 kg·kg^-1N in removing weeds at jointing stage.Nitrogen physiology efficiency of removing weeds at reviving stage was the highest to 57.5 kgN·kg^-1N, than others'' treatments.Analysis of the nitrogen efficiency and the yield efficiency,the time of removal weed should be in prohase of winter wheat,especially in over-winter and reviving stage.