Properties Of Organic Carbon And Nitrogen Transformation In Eroded Brown Soil And Their Environmental Impact

Changes of labile organic carbon were investigated in seriously eroded brown soils under different using methods or different erosion positions in northwest of Liaoning province, and the process of nitrogen transformation and its contribution to the greenhouse effect were also studied. The results showed that the SOC-C content of young pine soil was only 50% of other vegetation soil, and the lowest labile organic carbon suggested the lowest ability to improve soil fertility of young pine soil. and moreover, macro-aggregate content in other kinds of soil was 3.46~5.46 times more than young pine soil, while particulate organic carbon content was 2.01~3.56 times, except that farmland maize was more or less, thus aggregates of young pine soil had the lowest stability. In addition, respiration and mineralization of young pine soil were significantly greater than other vegetation types of soil, so indolent carbon content was little which was disadvantage to the formation of carbon sink. For the same reasons, soils of natural weed and alfalfa can form a potential carbon sink. From the perspective of soil and water conservation, young pines should be cautious to take into account, and priority should be given to grasses vegetation. Compared to farmland maize, terrace maize soil was better for soil and water conservation for that >2mm macro-aggregate content of terrace maize was higher. SOC, LFOC, HWC, CWC and MBC in sloping land soil migrated vertically along with erosion, removal and accumulation by water on the slope. The size of aggregates in eroded soil was mainly below 250 mm. Moreover, the content of POC in macro-aggregates nearby sediment zone at foot-slope reached to 9.77 mg kg-1 which was 1.75 times more than those of summit and 1.62 times more than shoulder-slope. HWC, CWC, and MBC in s soils under different using methods or different erosion positions correlated significantly linear to SOC (p<0.01). HWC could best delegated the change of SOC. Different forms of active carbon had good correlativity, of which CWC and MBC (R2=0.998) were correlation significantly. Nitrification is the main process of N2O production at soil water content of 70%WHC, and at 100% WHC denitrification is the primary process of N2O production. Heterotrophic nitrification and the ability of N2O reduction to N2 are weak.