Relationship Between Organic Carbon And Climatic Factors Of Black Soil In Farmland In Northeast China

Soil is the largest carbon pool in the terrestrial biosphere,and even small changes in soil organic carbon can have a profound effect on atmospheric carbon dioxide(CO2)concentrations.Soil aggregate,which are the main reservoirs of SOC,provide physical protection for soil organic carbon(SOC),which is an important mechanism for carbon fixation.The organic carbon in soil aggregate is affected by many factors.This paper mainly studies the relationship between organic carbon and climatic factors in farmland black soil in Northeast China.In this paper,46 dry soil samples with similar farmland management measures in the typical black soil area of Northeast China were selected,and soil samples were collected at different tillage levels.The samples were distributed from Nenjiang County in Heilongjiang Province to Gongzhuling City in Jilin Province in the south.The changes of soil organic carbon in different climatic conditions and different tillage levels were discussed.The results show:(1)In the northeastern part of China,the annual average temperature and annual precipitation gradually decrease from south to north,and the annual average temperature is in the range of 1.2-6.5 ?.The soil organic carbon in the cultivated layer increases with the annual average temperature and effective accumulated temperature.High and decreasing,the annual organic soil carbon decreased with the increase of annual precipitation in the area of 453-621mm;the change of organic carbon in the bottom and bottom soil layers with annual average temperature,effective accumulated temperature and water temperature ratio The amplitude is weaker than the plough layer.(2)The organic carbon in the >2mm aggregate has the largest change with the annual average temperature,effective accumulated temperature and annual precipitation.The variation of organic carbon with different average particle size,effective accumulated temperature and water temperature ratio and plowing Similar to the layer,Only >2mm agglomerate organic carbon in the subsoil is affected by climatic conditions.(3)The contribution rate of organic carbon to soil aggregate of 2-0.25 mm aggregate at the bottom of the plough is the largest with annual average temperature and effective accumulated temperature.The contribution rate of 2-0.25 mm aggregate to organic carbon is the average temperature.The change in effective accumulated temperature is similar to that of the plow floor.The contribution of the subsoil aggregate to organic carbon is not affected by climatic conditions.(4)In the screening of the factors affecting soil organic carbon in the plough layer and the plough bottom layer,the annual average temperature is the main factor affecting the soil organic carbon in the plough layer and the plough layer.The soil organic carbon in the plough layer is significantly affected by the annual precipitation.Field water holding capacity is one of the factors affecting the change of soil organic carbon in the plough layer and the bottom layer.(5)In addition to the <0.053 mm micro-aggregation of the plough layer,the organic carbon in the soil aggregate of the plough layer and the plough layer was significantly changed by the annual average temperature,and the large aggregate changed more with the annual average temperature than the micro-aggregate,with the cultivation.As the level deepens,the variation of organic carbon in soil aggregate decreases with the annual average temperature.The organic carbon in the soil aggregate at the bottom of the plough is significantly affected by the water holding capacity in the field.The soil organic carbon in the subsoil is almost unaffected by the annual average temperature.