云南烟田耕层土壤有机碳空间分布特征及影响因素分析OA

To enhance the role of soil organic carbon in addressing climate change and regulating soil fertility,physical and chemical properties of topsoil(0-30 cm)from 14 501 sampling points in Yunnan tobacco fields in 2018 were surveyed.Organic carbon contents,organic carbon density,and carbon stock in topsoil from counties,major tobacco growing regions and the province-wide tobacco fields were calculated.The spatial distribution characteristics were analyzed,and Pearson correlation and curve regression were used to quantify the driving factors influencing soil organic carbon contents in tobacco fields.The results showed that the average organic carbon content in the topsoil was 17.15 g/kg,with an average carbon density of 60.50 t/ha and a total carbon stock of 23.978 million tons.The ranking of soil organic carbon contents in the topsoil across different tobacco growing regions in descending order was east Yunnan,west Yunnan,southeast Yunnan,northeast Yunnan,central Yunnan and southwest Yunnan,the ranking for carbon density was east Yunnan,west Yunnan,central Yunnan,southeast Yunnan,northeast Yunnan and southwest Yunnan,for soil carbon stock was west Yunnan,east Yunnan,central Yunnan,southeast Yunnan,southwest Yunnan and northeast Yunnan.It was found that organic carbon content in the topsoil of tobacco fields was strongly positively correlated with soil alkali-hydrolyzable nitrogen,available phosphorus,available potassium and average annual precipitation(p<0.01),significantly negatively correlated with average annual temperature and average annual sunshine hours(p<0.01),and negatively correlated with soil pH value(p<0.05).Among these,alkali-hydrolyzable nitrogen content was the primary explanatory factor for the spatial variation of organic carbon content in topsoil.Accurate and systematic evaluation of soil organic carbon in tobacco fields at the regional scale in Yunnan Province provides important references for improving soil fertility and productivity.