Crop Production And Greenhouse Gas Emission As Affected By Fertilization,Tillage And Straw Management

Excessive fertilization,frequent cultivation and irrational straw management have led to a range of environmental problems in the winter wheat-summer maize system,such as lower nitrogen utilization efficiency and greenhouse gas emissions.Therefore,it is a prerequisite to realize the sustainable development of agriculture in the North China Plain(NCP)by improving fertilizer nitrogen,tillage,and straw management to increase nitrogen utilization efficiency and reduce greenhouse gas emission.To explore the effects of those three measurements on nitrogen utilization efficiency and greenhouse gas emission,in this research,we study the winter wheat-summer maize production system of intensive agricultural production in the NCP.Field trials,with 3×2×2 factors,include tillage:no-tillage(NT)and rotary tillage(RT);straw management:straw removal(NS)and straw incorporation(S).Fertilizer N rates:Control without N fertilizer application(CK),Optimized N fertilizer rate(OPT)and Farmers’conventional N fertilizer rate(CON).Calculate greenhouse gas emission from agricultural production,statistical soil nitrogen losses,by monitoring gas emissions and crop production.We mainly researched the effects of fertilization,tillage and straw on yield,greenhouse gas emissions,and soil NH3 volatilization.We analyzed systematically the effects of N fertilization,tillage and straw management on crop yield,nitrogen use efficiency,greenhouse gas emissions,soil NH3 volatilization,and trying to analyze the soil nitrogen balance.Our research reveals that:(1)In this study,based on fertilizer nitrogen,tillage and straw incorporation,the wheat yield is increased by increasing spike number unit area,and the increasing maize yield led to the spike number unit area and 1000 grains weight.Compared with conventional measures(CON,RT,and NS),the wheat yield under optimized N fertilizer rate,no-tillage and straw removal was increased by 1.32%,6.34%and 4.33%,respectively,the main reason was spike number increased 7.81%,7.12%and 10.3%,respectively.The tillage x straw interaction has the significant effect on wheat spike number.The wheat yield of NTxS treatment was increased by 14.6%as compared to the average value of other treatments due to the higher spike number(increased 20.9%).Although no significant interactive effect was observed on wheat yield under the fertilization x straw interaction,the spike number of OPT x S treatment was 6.38%higher than that of average value.Compared with conventional measures(RT and NS),the 1000 grains weight and spike number of maize increased by NT and S measure,which improved the yield by 2.71%and 4.26%,especially the less rainfall period(such as the 1st maize season).There was no significant effect on maize yield between OPT and CON.Although the interaction has no significant effect on maize component element,the 1000 grains weight under the NS×S treatment was 9.32%higher than that of average value during the less rainfall period.(2)Compared with CON and RT,OPT and NT increased significantly the Nitrogen use efficiency,but no significant effect was observed on straw management.N fertilization rate decreased 35%by OPT as compared to CON,but the crop yield and N uptake didn’t decreased by OPT,thus Nitrogen utilization efficiency(NUE),apparent Nitrogen utilization efficiency(ANUE),Nitrogen recovery efficiency(REN)and Partial factor productivity of fertilizer Nitrogen(PFPN)under OPT was increased by 37.5%,44.9%,35.1%and 51.6%compared with CON.The grain N uptake of maize under NT was 4.34%higher than that under RT,thus the NUE and ANUE in maize season increased by NT,and the enhancement trend of REN also was observed under NT compared with RT,but no significant effect was found in the wheat season.The fertilization × tillage interaction take the significant effect on NUE in the maize season,such as the NUE under the OPT × NT treatment was 72.8%higher than that of average value.The tillage × straw interaction has the significant effect on ANUE in the wheat season.ANUE under NTS was 11.4%higher than that under other measurement(3)OPT plus NT and S decreased greenhouse gas emission and intensity.Fertilizer production,irrigation and N2O emission was the main emission source of the winter wheat-summer maize production system,which accounted of 49.1%,25.8%and 14.4%in total greenhouse gas warming potential.Compared with CON,OPT decreased N2O emission by 36.4%and 31.1%in wheat and maize season,respectively.N20 emission was increased by 20.8%and 75.0%under NT in wheat and maize season,respectively,as compared to RT.The straw management has no significant effect on N2O emission.At CON,S measurement increased 47.8%and 31.3%of N20 emission in wheat and maize season,respectively,compared with NS measurement.In contrast,S measurement at OPT reduced 20.0%of N2O emission in the maize season compared with NS measurement,and no effect in the wheat season.Although soil served as a sink for CH4,which just represents 2.92%of N2OCO2-eq.Greenhouse gas warming potential and greenhouse gas intensity(GHGI)of farmland at OPT was 33.8%and 32.9%lower than that at CON,respectively.Compared with RT,NT increased significantly tht greenhouse gas warming potential(76.4%)and GHGI(72.4%)of farmland,but not significant in the wheat season.There was no significant effect of straw management on the greenhouse gas warming potential and GHGI of farmland.Compared with NS and OPT,S and CON increased significantly total greenhouse gas warming potential(8.77%and 28.1%),and in the wheat season,total greenhouse gas warming potential at NT was 6.70%lower than that at RT.Tillage has no significant effect on the total greenhouse gas warming potential in the maize season.Tillage and straw management has no significant effect on the total GHGI,and OPT decreased the total GHGI by 21.4%as compared to CON due to decreasing the indirect greenhouse gas warming potential.(4)Reckon up the soil nitrogen balance of the year 2013-2014,the result stated that the soil total nitrogen increased by 98.5(OPT)and 146.2 kg N ha-1(CON)under the straw removal.However,under straw incorporation,the amount of increasing soil total nitrogen was 206.4(OPT)and 281.8 kg N ha-1(CON).This result stated that the main reason was straw incorporation which led to the difference of soil nitrogen in this area,and under the high N fertilization(690 kg N ha-1),the amount of increasing soil nitrogen was 47.7(NS)and 75.3 kg N ha-1(S)higher than that under optimal N fertilization(450 kg N ha-1).Therefore,compared with OPT,the higher N fertilization caused the higher accumulative soil nitrogen,unless the higher NH3 volatilization and the higher N leaching.The accumulative soil nitrogen was better for crop uptake,but this increased the NH3 volatilization,greenhouse gas emission and N leaching.At CK treatment,the deficit of soil nitrogen was 10-53 kg N ha-1,which stated the N fertilization was the necessary for the high and stable yield.The increasing soil total nitrogen occurred in the wheat season,and it was found the deficit of soil total nitrogen in the maize season due to the high N leaching.The soil inorganic nitrogen was decreasing in the wheat season,but it was increasing in the maize season.However,the different trend of soil organic nitrogen was found.The increasing soil organic nitrogen was observed in the wheat season,but in the maize season,the soil organic nitrogen was much decreasing.Compared with CON,NH3 volatilization decreased significantly 41.6%by OPT,and straw management has no significant effect on NH3 volatilization.This research stated the OPTxNTxS increased the crop yield due to increasing wheat spike number and maize spike number and 1000 grains weight as compared to other treatments.At OPT,S treatment decreased N2O emission and global warming potential from farmland.Compared with NS treatment,soil organic nitrogen was increased by S treatment.The increasing soil total nitrogen occurred during the wheat season under N fertilization.Compared with CON,NH3 volatilization decreased significantly by OPT.