灌溉与施氮对留茬免耕春小麦氮素吸收和氮肥损失的影响

Effects of Irrigation and Nitrogen Supply Levels on Nitrogen Uptake and Fertilizer Nitrogen Loss of Spring Wheat on No-tillage with Stubble Standing Farmland

在甘肃省石羊河流域绿洲灌区,采用裂区设计大田试验,研究不同灌溉量(常规灌溉(327 mm)、节水20%灌溉(261 mm)、节水40%灌溉(196 mm))和施氮量(0,140,221,300 kg/hm2)对留茬免耕春小麦植株吸氮量、收获期土壤硝态氮(NO3--N)含量和氮肥损失的影响。结果表明,在留茬免耕农田中,灌溉量从196 mm增加到327 mm,小麦籽粒含氮量从1.55%增加到1.71%,植株吸氮量从134 kg/hm2增加到190kg/hm2。当施氮量超过221 kg/hm2时,籽粒含氮量、秸秆含氮量、植株吸氮量不再显著增加。施氮300,221,140 kg/hm2处理的植株吸氮量比不施氮处理的分别提高47%,37%和18%;在春小麦收获期,土壤表层(0-60 cm)NO3--N含量随灌溉量增加而减少,随施氮量增加而增加,灌溉和施氮对60 cm以下土壤NO3--N含量影响不明显。与不施氮处理相比,施氮300,221,140 kg/hm2的氮肥损失分别为186,137,94 kg/hm2。

A combination of careful irrigation and nitrogen（N） management is needed to improve N uptake efficiency and to minimize fertilizer N loss in the arid oasis agricultural area of northwest China.A field experiment was conducted to investigate the effects of different irrigation and N application rates on plant N uptake,soil nitrate nitrogen（NO3^--N） distribution in soil profile and fertilizer N loss on no-tillage farmland with standing stubble in the oasis region of Shiyang river basin,Gansu province.The experiment followed a completely randomized split-plot design,taking flood irrigation（conventional irrigation（327 mm）,20% water-saving irrigation（261 mm）,40% water-saving irrigation（196 mm）） and N fertilizer application rates（0,140,221,300 kg/hm^2） as the main-plot and split-plot,respectively.Under the experimental condition,nitrogen contents in grain yield increased from 1.55% to 1.71%,and plant N uptake increased from 134 kg/hm^2 to 190 kg/hm^2 within amount of irrigation water increased from 196 mm to 327 mm.Nitrogen contents in grain yield and in straw yield,and plant N uptake did not increase significantly when N rate was above 221 kg/hm^2.Compared with no N application,the increases of plant N uptake,in 300,221,140 kg/hm^2,were 47%,37% and 18%,respectively.At harvesting stage,the NO-3-N contents in 0-60 cm depth soil profiles decreased with the amounts of irrigation and increased with N supplies,and irrigation and nitrogen supply levels had not evidently affect on NO3^--N contents below 0-60 cm depth in soil.Compared with no N application,the increases of fertilizer N loss,in 300,221,140 kg/hm^2,were 186,137,94 kg/hm^2,respectively.