Effects Of Tillage And Nitrogen Fertilizer On Soil Water And Nitrogen Content And N₂O Emissions In Summer Of Replanted Farmland

Greenhouse gas is an important factor causing global climate change,and N₂O is a greenhouse gas with large warming potential and long lifecycle,which mainly comes from farmland soil.Mainly chisel-plow-tillage and zero-tillage conservation tillage is regarded as a kind of improving soil physical and chemical properties,agricultural management measures to reduce the soil nitrogen loss,in the north of China is a wide range of promotion,but the current conservation tillage effect on greenhouse gas emissions is controversial,some studies have shown that conservation tillage can reduce greenhouse gas emissions,and some research results on the contrary;In addition,nitrogen fertilizer is the direct source of N₂O,and there is a widespread phenomenon of excessive use of nitrogen fertilizer in Chinese farmland.Based on this,a two-year experiment was conducted in which three tillage types were set up:chisel-plow-tillage（CPT）,zero-tillage（ZT）,and tillage（PT）.Two nitrogen levels were N1(180 kg N·hm^-2)and N2(240 kg N·hm^-2).Two crops:Soybean（S）,corn（C）,using static box method on N₂O emissions were determined,and the soil physical and chemical properties and crop yield were determined,and aims to find the best way to handle it,farmland to reduce N₂O emissions,stable high yield of crops,the goal of improve the farmland soil environment provided the scientific basis and technical support,to achieve healthy and sustainable development of agriculture.The main results are as follows:（1）Conservation tillage can improve the soil environment of corn and soybean farmland.The soil moisture content of CPT and ZT in protective tillage increased by1.14%-16.86%and 0.29%-20.44%,respectively,the nitrate nitrogen content of 0.001%-23.53%,0.04%-42.30%,and the 0-20 cm soil nitrate content of 22.16%-202.50%and18.35%-103.98%,respectively,and inhibited the loss of nitrate nitrogen.（2）In dryland of northwest China,conservation tillage and nitrogen fertilizer had significant effects on soil N₂O emission.On the whole,the flux of Soil N₂O emission is ZT>PT>CPT,N2>N1,Corn>Soybean;Soil N₂O emission flux under ZT-N1 and PT-N1treatments was soybean>Corn.Both conservation tillage and nitrogen fertilizer had significant effects on N₂O cumulative emissions and N₂O emission intensity.In soybean and maize fields,under the same nitrogen fertilizer treatment,chisel-plow-tillage significantly reduced N₂O cumulative emissions by 3.83%-26.29%（N1）and 8.18%-57.36%（N2）.N₂O emission intensity decreased by 18.75%-32.01%（N1）and 18.75%-38.16%（N2）;In addition,zero-tillage reduced N2 O emission intensity by 11.11%-16.00% in soybean fields.Under the same tillage treatment,N2 O cumulative emission and N2 O emission intensity were significantly reduced by 19.05%-73.77% and 5.45%-63.79% compared with N2.In addition,this study found that planting soybean significantly reduced soil N2 O cumulative emissions by 12.36%-62.85% compared with planting maize.（3）In soybean and maize fields,under N1 treatment,compared with tillage,the yield of maize and soybean was decreased by 17.84% and 6.10% under chisel-plow-tillage,while the yield of maize and soybean was increased by 15.68% and 21.69% under zero-tillage.Under N2 treatment,the yield of maize and soybean was increased by 26.68% and 1.24% under chisel-plow-tillage,and the yield of maize and soybean was increased by 3.52% to 4.00% under zero-tillage.In addition,nitrogen reduction reduced soybean and maize yields by 9.30% and 21.93% in the subsoil tillage.In zero-tillage and tillage fields,nitrogen reduction increased maize yield by 11.20% and 11.71%,and soybean yield by 10.78% and 1.16%.In conclusion,chisel-plow-tillage can significantly reduce soil N2 O emission flux,soil N2 O cumulative emission and soil N2 O emission intensity,and improve the physical and chemical properties of farmland soil,which has good ecological benefits and is conducive to promoting the healthy and sustainable development of agriculture.In addition,zerotillage treatment increased yield,improved soil environment,and reduced soil N2 O emission intensity in soybean fields,which gave consideration to both ecological benefits and soybean yield.At the same time,nitrogen reduction treatment significantly reduced soil N2 O emission,and improved crop yield in zero-tillage and tillage farmland.Therefore,the combination of zero-tillage and nitrogen reduction can better balance ecological benefits and production benefits.Finally,compared with corn fields,soybean fields have lower soil N2 O emissions,and soybean fields have better emission reduction potential.