The Research Of Carbon Footprint Of Different Rotations In Guanzhong Irrigation Region

By building models and fixed-point test methods, this experiment used two rotationmodes,which are maize-wheat and maize-rapeseed in Guanzhong irrigation district as theresearch objects. There are two factors in each rotation,which are straw returned andfertilization. The straw returned has three levels: no returning, half amount of returning,total amount of returning. The fertilization also sets three levels: no fertilization,80%fertilization and total amount fertilization. There are nine treatments in total. This experimentcalculated the carbon footprint of different rotation patterns, analysed the relationshipbetween straw returned, fertilization and the carbon sequestration in the process of production,soil carbon dioxide emissions, soil nitrous oxide emissions, soil temperature, moisture. Mainconclusions are as follows:There are obviouse differences between wheat-maize and maize-rape rotation modes.The carbon footprint of wheat-maize rotation mode is more than maize-rape rotation mode. Inthe process of wheat-maize rotation mode, the influence of straw returned on carbon footprintis half amount returning> no returning> full amount returning; the carbon footprint of MN ishighest,748888.5kg· hm-2·yr^-1; the carbon footprint of QN is least,421547.1kg· hm-2·yr^-1.In the process of maize-rape rotation mode, the influence of straw returned on carbonfootprint is full amount returning> half amount returning>no returning; the carbon footprintof MC is highest,269528.8kg· hm-2·yr^-1; the carbon footprint of NN is least,133400.3kg· hm-2·yr^-1.In the process of wheat-maize rotation mode, the amounts of crop carbon dioxidesequestration are74519.7kg·hm^-2. In the process of maize-rape rotation mode, the amounts ofcrop carbon sequestration are47679.15kg·hm^-2. The wheat-maize t rotation mode is36%higherthan maize-rape rotation mode. In the process of wheat-maize rotation mode, the influence ofstraw returned on carbon dioxide sequestration is no returning>full amount returning> halfamount returning; In the process of maize-rape rotation mode, the influence of straw returned on carbon dioxide sequestration is half amount returning> full amount returning>noreturning.Whatever it’s in the process of wheat-maize rotation mode or in the process ofmaize-rape rotation mode, the overall trend of carbon dioxide flux of different treatments iswave of change. The whole characteristics of the soil carbon dioxide flux is that summer ishigher than winter. In the process of wheat-maize rotation mode, carbon dioxide emission fluxof half amount returning is greater than no returning; carbon dioxide emission flux offertilization is greater than no fertilization. In the process of maize-rape rotation mode, theinfluence of straw returned on soil carbon dioxide flux is full amount returning> half amountreturning>no returning; carbon dioxide emission flux of fertilization is greater than nofertilization.In the two rotation modes, the whole trend of the temperature in different treatment issimilar: with the increase of soil depth, the temperature is gradually lower.In the entirerotation process, the trend of temperature is first reduce and then rising. The change oftemperature is similar to soil respiration flux. In the two rotation modes, the whole trend of themoisture in different treatment is similar: with the increase of soil depth, the moisture isgradually lower.In the entire rotation process, the moisture of August、September is highest.the moisture of June is least.In the two rotation modes, the relationship between nitrous oxide emission andrainfall、 fertilizeration in different treatments is positive correlation. In the process of maize,under the whole amount of fertilizer application condition, the amount of nitrous oxideemissions is42.8kg/hm²; Under the condition of80%fertilizer, annual emissions of nitrousoxide is35.97kg/hm²; Under the condition of no fertilizer, annual emissions of nitrousoxide is8.7kg/hm². In the process of the growth of winter wheat, winter rape, under thewhole fertilizer condition, nitrous oxide emissions is50.3kg/hm²; Under the80%fertilizercondition, annual emissions of nitrous oxide is41.4kg/hm²; Under the no fertilizer condition,annual emissions of nitrous oxide is5.7kg/hm².