Impact Of Annual Straw Management And Fertilizer On Agriculture Ecosystem Greenhouse Gas Emissions And Productivity In Wheat-Maize Rotation System

Global climate change was significantly affected by the emission of greenhouse gas?GHGs?And its effect on the agriculture sector cannot be avoid.This region is maize-wheat rotation was generally used and its straw was reused,which can significantly increase carbon sequestration and crop yield.The sustainable development of agriculture limited due to the low level use efficiency of crop straw and unreasonable fertilization of wheat-maize rotation system in guanzhong,china.The treatments imposition was started since October 2011 and this research as a part of long-term trial.The experimental plots have been arranged in three different straw input levels?NS:no straw input;HS 50%amount of field straw input;S:100%amount of field straw input?and three different fertilizer levels?NF:no fertilizer;F0.8:decreased 20%for conventional fertilizer;F:conventional fertilizer?,respectively,total 9treatments?NS+NF;NS+F0.8;NS+F;HS+NF;HS+F0.8;HS+F;S+NF;S+F0.8;S+F,respectively?.The contents of this study were exploration the farmland productivity;characteristic of soil organic carbon pool and characteristic of soil GHGs emissions in response to different straw management and fertilizer levels,respectively,during 2015-2018,and estimation the agro-ecosystem greenhouse effect of different straw input levels and fertilizer levels combined treatments under wheat-maize rotation system.The objective of this study to determine effects of different straw input on variation in grain production;soil carbon sequestration and characteristic of GHGs source/sink for wheat-maize rotation system,and the research conclusion as the theoretical and practical basis for achievement green production of agriculture and development low carbon agriculture for Guanzhong plain in the future.The results are as follows:Straw input and fertilizer increased crop grain yield,biomass,the utilization efficiency of water and nitrogen for wheat-maize rotation system.For crop grain yield and biomass,the difference between F0.8 treatment with F treatment were less,F0.8 treatment increased grain yield by 26.3-34.8%?wheat?and 15.3-25.0%?maize?than NF treatment,respectively.F0.8treatment significantly increased over ground biomass by 27.2-46.9%?wheat?and 26.1-44.8%?maize?than NF treatment and it's also increased underground biomass 16.5-26.3%?wheat?and 40.6-69.5%?maize?than NF treatment,respectively.Under the condition of fertilization,The S treatment were increased grain yield by 6.6-12.7%?wheat?and 2.2-5.1%?maize?than NS treatment,respectively,and it's also significantly increased over ground biomass by3.8-12.7%?wheat?and 5.1-9.3%?maize?than NS treatment.F0.8 treatment were significant increased PEP_N,AE_N and NUE for wheat and maize than F treatment,respectively;and S and HS treatments were significant increased partial factor productivity of nitrogen?PEP_N?,agriculture effective of nitrogen?AE_N?and nitrogen use effective NUE for wheat and maize than NS treatment,respectively.The F0.8 treatment was significantly increased water use effective?WUE?by 22.3-39.5%?wheat?and 16.3-24.7%?maize?than NF treatment,respectively.The S treatment were significant increased the soil water storage for crop sowing and crop harvest than NS treatment.The S treatment significantly increased WUE by3.2-14.9%?wheat?and 0.1-11.7%?maize?than NS treatment,respectively.The soil organic carbon?SOC?content in the upper soil layers was more affected by straw input combine with fertilizer than deeper soil layers.F0.8 treatment was increased SOC content significantly in 0-40cm soil depth 7.5-42.3%than NF treatment;however,S treatment was significant increased SOC content in 0-20cm soil depth 3.1-10.3%than NS treatment.The significantly effects to SOC storage on straw input combine with fertilizer was found in research,F0.8 treatment was significant increased SOC storage 4.9-16.2%than NF treatment;however,S treatment was increased significantly SOC storage 13.3%than NS treatment.In addition,fertilizer application significantly increased the content of soil dissolved carbon?DOC?,labile organic carbon?LOC?and particulate organic carbon?POC?in different soil depths,respectively.The S treatment significant increased the content of DOC,LOC and POC and its percentage of SOC in different soil depths than NS treatment,respectively.Furthermore,as the NS+NF treatment for a reference,F treatment and F0.8treatment were significant increased carbon pool management index?CPMI?than NF treatment,respectively,while,the S treatment also was significant increased CPMI than NF treatment under the condition of fertilizer.A seasonal characteristic was confirmed for GHGs emission,and the minimum value showed in winter,while the maximum in summer,respectively.Straw input and fertilizer increased the growth period cumulative emissions of CO₂ and N₂O,respectively.The F0.8treatment were increased significantly the growth period cumulative emissions of CO₂2.9-10.0%?wheat?and 3.5-6.0%?maize?than NF treatment,respectively;while it's were also increased for N₂O 50.5-67.3%?wheat?and 78.7-93.6%?maize?than NF treatment,respectively.In a similar way,under the condition of fertilizer,the S treatment were significantly increased the growth period cumulative emissions of CO₂ 3.6-5.7%?wheat?and1.5-3.9%?maize?than NF treatment under the condition of fertilizer,respectively;while also significantly increased growth period cumulative emissions of N₂O 14.7-27.8%?wheat?and8.7-27.4%?maize?than NS treatment,respectively.Meanwhile,the S+F treatment significantly increased the growth period cumulative emissions of CH₄ 5.1-8.1%?wheat?and5.1-16.2%?maize?than NF+NS treatment,respectively.Correlations were showed among Sol CO₂ emission with the soil moisture and soil temperature,soil organic carbon active component,C-cycle enzymes.Soil CO₂ emissions increase with the increasing of in soil temperature,and 76.4-81.6%of the variation could be explained by seasonal variation in soil temperature in the wheat season.Similarly,66.1-73.4%of the variation in soil CO₂ emissions is recorded by seasonal variation in soil temperature corresponded to seasonal variation of soil temperature in maize season.Soil CO₂ emissions change with the increase of soil water content,and 14.6-41.4%%of the variation could be explained by seasonal variation in soil water content in the wheat season.Similarly,10.5-22.1%of the variation in soil CO₂ emissions is recorded by seasonal variation in soil temperature corresponded to seasonal variation of soil water content in s in maize season.The temperature sensitivity of soil CO₂ emissions(Q₁₀)were estimated 1.84-2.44?wheat?and 1.88-2.10?maize?,respectively and the Q₁₀ decreased with the increase in straw return,and straw mulch,respectively.Significant or high significant positive correlations were showed among Sol CO₂ emission with the soil microbial biomass carbon?MBC?,?-Glucosidate,Cellulase,Invertase in wheat and maize growth period,respectively.100%field straw input and fertilizer were significantly increased NPP of global warming potential(GWP_NPP)and GHGs emissions of global warming potential(GWP_GHGs)for wheat-maize rotation,respectively.It's showed that carbon sequestration was high than carbon consumption when fertilizer was used in maize-wheat rotation,and it is because of the GWP_NPP high than GWP_GHGs.On the other hand,the net global warming potential??GWP?was greater than zero,means the wheat-maize rotation is a greenhouse sink.Straw input and fertilizer were increase?GWP and GHGs emission intensity?GHGI?,especially,S+F0.8 treatment significant decreased net emissions of Greenhouse gas 1228-1731kgCO₂/hm² than NS+F0.8,and also decreased net emissions of Greenhouse gas 898-1535kgCO₂/hm² than NS+F,respectively.Overall,the annual straw input combined with the decreased in 20%for conventional fertilizer under wheat-maize rotation in Guanzhong plain,can improve the farmland productive and soil organic carbon sequestration simultaneously to reduce the GHGs emissions effect obviously.