Effects Of Carbon And Nitrogen Addition On The Stability Of Soil Organic Carbon Pool Of Dry Farmland In Longzhong Loess Plateau

Changes in soil carbon pools have seriously affected changes in atmospheric CO 2 concentration and global climate.Aiming at the problems of severe soil erosion,low soil fertility level,and extremely poor carbon pool stability in the Longzhong Loess Plateau,in order to better and permanently improve soil fertility,improve the effect of soil carbon sequestration and emission reduction,and achieve sustainable agriculture Sexual development.Through the long-term positioning test in Lijiabao Town,Dingxi: three nitrogen levels(CN0,CN50,CN100)levels(no nitrogen application,nitro gen application 50 kg·hm-2,nitrogen application 100 kg·hm-2)and Added with biomass charcoal(BN0,BN50,BN100),straw(SN0,SN50,SN100)(a total of 9 treatments,planted for two years)and in-situ cultivation test: different carbon to nitrogen ratios(12,15,18,21,24,27,30)Add two organic materials of straw and biomass char under the control(15 treatments(CK,S12,S15,S18,S21,S24,S2 7,S30,B12,B15,B18,B21,B24,B27,B30),360 d,11 cycles);explore its effect on the stability of soil organic carbon pool of dry farmland in Longzhong Loess Plateau;by measuring soil organic carbon,active organic carbon components,soil humus,and using analysis of variance And correlation analysis methods,aimed at exploring the content and distribution characteristics of soil organic carbon and its carbon components and their distribution characteristics,influence mechanism,and conversion relationship between the components under the control of carbon and nitrogen addition and different carbon to nitro gen ratios.Provides methodological support for soil carbon sequestration and emission reduction in plateau areas to stabilize carbon in farmland ecosystems The carbon conversion mechanism provides certain theoretical support.The research results are as follows:1.Compared with no nitrogen application,the remaining carbon and nitrogen addition methods can significantly increase the soil organic carbon content,and the effect of BN100 treatment is the most significant,and each soil layer is increased by 84.7%,69.3%,47.8% from shallow to deep.Compared with soil organic carbon,the effect of each treatment on the content of each active organic carbon component in the soil was the most significant with SN100 treatment,and it was significantly higher than that without and without nitrogen fertilizer treatment.2.Compared with no nitrogen application,the remaining carbon and nitrogen addition methods have increased the humus carbon content of farmland soil to varying degrees,showing a trend of gradually decreasing as the soil layer deepens;SN100 treatment has the most significant effect of increasing HA content,BN100 The effect of treatment on FA and Hu content was the most significant.With the increase of year,the addition of straw and biomass char under conventional nitrogen application increased the soil humus content significantly;HA / FA,?log K,E4 / E6 values under SN100 treatment Are higher than other treatments.3.The addition of straw and biomass carbon with different carbon content increased the content of soil organic carbon and activated organic carbon in different degrees at the beginning of the cultivation;after 360 days of cultivation,the effect of nitrogen addition on it compared to CK Smaller,the addition of biomass carbon significantly increased the content of soil organic carbon,and the addition of straw significantly increased the content of each component of soil active organic carbon.The higher the carbon-to-nitrogen ratio,the higher the content of soil organic carbon and active organic carbon components.4.The addition of straws with different carbon contents and biomass carbon increased the soil humus carbon content to different degrees at the beginning of the cultivation;after 360 days of cultivation,nitrogen addition had less effect on it compared with CK,biomass carbon The addition of fulvic acid and humicin content of the soil increased more significantly,and the addition of straw increased the humic acid content and ?log K,E4 / E6 values more significantly,which promoted the renewal of soil humus,and basically showed that the higher the carbon to nitrogen ratio,the more High trend.In summary,no matter whether it is nitrogen,straw,biomass carbon,or nitrogen and straw,biomass carbon are added together,they can increase the content of soil organic carbon and its carbon components to varying degrees.The addition of straw,straw and nitrogen The effect of improving the content of soil active organic carbon is better.The addition of biomass carbon,biomass carbon and nitrogen increases the content of soil organic carbon and humus carbon more significantly.The content is basically reduced as the soil layer deepens;the addition of straw significantly improves the activity of microorganisms,which is beneficial to the renewal of soil humus,the humic acid straw is sim...