Spatial Estimation Of Soil Organic Carbon Change And Yield Based On Dndc Model

The current study took the Wuyuer River Basin which is a typical black soil region as the research object, collected samples before sowing and after harvesting, analyzed samples by indoor experiment, and investigated the correlation and difference of soil organic carbon(SOC) among different crop types. Simulation of “point pattern” was applied based on DNDC model using the meteorological data and farm management data. The accuracy validation of the model was using the obtained soil attribute data. Then SOC contents and crop yield under different crop types were simulated by “regional pattern” under different contextual models. The conclusions were as follows:There were significant differences of SOC contents among different crop types, showing the order of paddy rice > corn > soybean. For SOC contents in corn crop type, the influence factors were SOC density, soil bulk density, p H and ammonium nitrogen. For SOC contents in soybean crop type, the influence factors were SOC density, pH and ammonium nitrogen. For SOC contents in paddy rice crop type, the influence factors were SOC density, soil bulk density, pH and particle size of <4 μm, 64~100 μm and >100 μm. The soil nitrogen has influence on the soil organic carbon, but not for all the soil nitrogen.There was significant positive correlation of soil organic carbon and ammonium nitrogen, but there was no relationship between soil nitrate nitrogen with soil organic carbon. Significant correlations of soil particle size components between soil organic carbon contents were only found in paddy rice. Particle size of <4μm with the most great content of 34.07% was significant positive correlation with soil organic carbon contents. Particle sizes of 64~100μm with the content of 4.11% and >100μm with the content of 7.83% were significant positive correlation of soil organic carbon.A better adaptation of the DNDC model in Wuyuer River Basin was found through "point pattern" of the study area, which will be suitable for promotion in Songnen Plain. SOC content in the surface soil of Wuyuer River Basin is 1.08 GtC, and the surface change of SOC contents was 48.2491 million tons C according to DNDC modeling. Wuyuer River Basin agricultural ecosystem is a "carbon sink". The effects of different crop types on the changes carbon contents were different. The carbon accumulation showed corn > soybean > paddy rice. Based on different scenarios simulation analysis, change in SOC showed a same growth trend with CO2 concentration(ppm), the proportion of straw returned and cultivation management pattern. That is to say the higher proportion of straw returned, tillage on soil disturbance, less is more beneficial to soil organic carbon pool. Under the assumption of the constant climate conditions, the most suitable cultivate management to improve crop yields is that to change the tillage depth to 5~10cm based on 100% straw returned in corn,soybean and paddy rice crops.