Research On The Variation Characteristics Of Soil Organic Carbon Pool And Its Carbon Sequestration Potentials In Cultivated Fields In Aohan County,Chifeng

Soil organic carbon(SOC)content played an important role in maintaining and improving soil fertility.This study was conducted to research the soil of farmland in Aohan,Chifeng,Inner Mongolia.Through field sampling and the way of the difference,correlation,path analysis and CCA sequencing analysis,we investigated the vertical variation of soil organic carbon in different farmland and the effects of topographic factors,soil physical and chemical properties and farmland management measures on SOC,then studied the soil carbon sequestration potential status of farmland,which can provide scientific reference and basic data for rational management and improvement of farmland soil carbon pool in Aohan County.The main conclusions were as follows:1.The frequency of soil organic carbon in Aohan County showed a normal distribution,and the mean value of soil organic matter in farmland was about 9.07g/kg,which was in a lack of state.The average value of organic carbon density was 1.66kg/m2,mostly in the range of 1.15?2.15kg/m2,the data was more discrete,which indicated that the distribution of soil organic carbon density was uneven.The soil organic carbon content of farmland decreased with soil depth increasing,which expressed the obvious characteristics of surface aggregation.The bottom soil organic carbon density was the highest among soil layers of different soil types,which was subjected to the more bigger long-term tillage compaction.In the soil within the depth of 60cm,the soil types with the largest and smallest organic carbon content and organic carbon density were all showed separately as:brown soil and aeolian sandy soil,and the soil organic carbon content and soil organic carbon density of irrigated land was more than dry land.Therefore,The expansion of irrigated land and brown soil farmland is favorable to the accumulation of SOC in farmland.2.The soil organic carbon content of different soil layer all presented as the trend ofdecreased first then increased with the increase of altitude and slope,The soil organic carbon content of shade aspect was significantly higher than that of sunny aspect(P<0.05).The effect of topographic factors,soil physical and chemical properties and farmland management measures on SOC content that from large to small was showed respectively as follows:altitude>slope>aspect,clay particles>water content>soil bulk density>total nitrogen>sand content>available potassium,straw returning>traditional tillage>film mulching.Through CCA comprehensive sequencing analysis,we can find that the main factors that affect the size of organic carbon content were as follows:management measures of farmland>soil water content>clay content>soil bulk density>altitude>slope.The soil fertility can be improved by no tillage and straw returning.3.Brown soil had relatively strong ability to stabilize soil carbon.The soil organic carbon reserves in the tillage layer and the depth of 60cm of farmland were 2.77 ×106t and 8.4 × 106t respectively.After returning farmland to forest,the ideal soil organic carbon sequestration potential in the tillage layer and the depth of 60cm of farmland were 2.70 × 106t and 3.21 × 106t respectively.Considering the food demand of the localpopulation,the area of farmland that can be reforested was 1216.5km.The realistic soil organic carbon sequestration potential were 2.09×106t and 2.46×106t respectively.