Simulation Research Of Soil Carbon Cycle In Wheat-maize Rotation Farmland Scale By DNDC Model

In order to explore the law of soil carbon cycle, providing the scientific decision basis toimprove the Guanzhong area dry land sustainable utilization of farmland soil ability. Throughfixed-point test, long-term observation, the research object is mainly about the commonmodel of winter wheat and summer corn crop rotation in the Guanzhong area and studies theimpact of two factors, straw returning to field and fertilizer processing, on the soil water hotand breathing discharge. The DNDC model of the simulation results were confirmed andanalyzed. Using the point simulation of the DNDC model to predict about the farmlandgreenhouse gas emissions and farmland soil carbon cycle under long-term differentprocessing. Systematically studied the different treatment on greenhouse gas emissions, soilcarbon source sink role and influence on the organic carbon content and reserves under therotation modeThe main conclusions are as follows：(1)Under different straw returning to field and fertilizer levels, there is no significantdifference between the soil temperature of each growth period arable layers under differenttreatment. Overall, half the amount of straw returning to field treatment on the effect of soiltemperature is most obvious. Soil moisture content between different processing have almostthe same change trend. The greater amount of straw returning to field, the water retentioneffect of straw returning is more obvious. Soil respiration rate has obvious seasonal changelaw. During the winter wheat growth period, Emissions rule is rising, reducing, increasing,reducing; During the summer maize growth period, it is showed out the law that, increasingwith plant growth–surging with fertilizer processing-slowing down with the decreasinggrowth. The influence of different straw returning to field treatments is not obvious, betweenfertilizer and no fertilizer processing the effect is significant. The emission rate of carbondioxide is largest under half amount of straw returning to field balanced fertilization(2) The simulation results of DNDC model are accurate on daily average temperature,the top layer soil temperature, soil CO2emission rate and are also significant correlation.Through the model sensitivity analysis, it is known that it can affect the dynamic change ofsoil organic carbon, reduce the emissions of CO2, CH4and N2O and other greenhouse gasesby controlling the proportion of straw returned and fertilizer. （3）Long-term different straw returning to field and fertilizer treatment on the impact ofgreenhouse gas emissions, soil carbon cycle, organic carbon content and organic carbonreserve volume are different.The full amount of straw to field processing and reduction ofconventional have the greatest impact on absorption of CO2and CH4, release of N2O, andpromote soil carbon sequestration with the most significant. They also increased organiccarbon content and reserves most significantly.