Effects Of Dryland Management Measures On Soil Organic Carbon And Carbon Sequestration Potential In Central China

Climate change,which is caused by abundant greenhouse gas emission,has been a global concerned environmental problem.Increasing soil carbon sequestration has proven to be an effective way to mitigate climate warming.Soil organic carbon pool is an important component of soil carbon pool,and the soil organic carbon pool in farmland accounts for a large share of global soil organic carbon pool.There is a significant difference of soil organic carbon when different management measures are taken in farmland.Clarifying the trend characteristics of soil organic carbon under different management measures,is meaningful for optimizing the management measures,improving crop productivity and soil fertility,and mitigating climate change.In this study,firstly,the Century model was verified,validated and evaluated by the measured crop yields and soil organic carbon monitoring data,which from the long-term experiment site of dryland rotation in central China.Secondly,the suitability of the model to simulate the change of soil organic carbon in dryland rotation in central China was determined,then the characteristics of soil organic carbon and the potential of soil carbon sequestration under single and combined farmland management measures were analyzed.And finally,the soil organic carbon variation trends under the current or the national policy planning rate of straw returned and the potential to reduce the application of nitrogen fertilizer while maintaining a certain amount of organic fertilizer were simulated and analyzed.The main conclusions of this paper are as shown below:(1)There are different trend characteristics of soil organic carbon in farmland under different management scenarios.Changing tillage mode to no-tillage could slow down the soil organic carbon reduction of 3.95%.The effects of fertilizing management on soil organic carbon and the potential of soil carbon sequestration have related with the amounts of nitrogen fertilizer and fertilization structure.Straw returning has been shown to be effective in improving soil organic carbon content and the potential of soil carbon sequestration,the soil organic carbon content is increased by 1932.77 g/m~2 while all straw returned,and the effect of maize straw returning is better than the wheat straw.There is interaction between different farmland management measures.(2)While maintaining the current or the national policy planning rate of straw returned unchanged,to maintain the current fertilizer measures could guarantee the relative stability and continuous accumulation of soil organic carbon,the potential of soil organic carbon sequestration with 706.51-1003.65 g/m~2,and crop yields remained relatively stable.(3)In the condition of maintaining a certain amount of organic fertilizer,the amount of nitrogen fertilizer was reduced by 30%(9.81g/m~2)in dryland of central China could maintain the relatively stable crop yields,and continuously improve the content of soil organic carbon.