On The Spatial Distribution Patterns Of Soil Organic Carbon In The Hainan Province

Soil carbon pool is the largest one stored in the earth surface system, and the stability and increase of soil organic carbon have been now well recognized internationally as one of the major means of slowing down the rise of CO2density in the atmosphere.Hainan province is a subtropical areas, located in the most southern part of china and have a unique climate. This area is an ideal for soil organic carbon research, which will be of specially significance in predicting the changes rule of organic carbon and stability.This dissertation has made a comprehensive study of the spatial distribution features of soil organic carbon in Hainan province by integrating multi-disciplinary theories and techniques. This study has chosen65typical profiles on the basis of a comprehensive survey of soil types and soil type distribution features. It has systematically collected soil samples and tested such indexes as soil organic carbon, oxygen-prone organic carbon, nitrogen, phosphorus, potassium, pH value, weight and viscous grain content; and also estimated the density and storage of soil organic carbon. This research aims to reveal the spatial differences of soil organic carbon. Such a system attic study yields certain conclusions as follows.(1) The soil organic carbon is one of decline in Hainan province, but the profile coefficient of variation of organic carbon of rice paddiesn dry land and forest land have bigger difference. The soil organic carbon in the dry land surface soil has an average profile content of9.12g/kg, the soil organic carbon in the forest land surface soil has an average profile content of9.50g/kg, the soil organic carbon in the rice paddies surface soil has an average profile content of11.13g/kg.(2) The organic carbon content is also very different even the soil types are different. The results showed that the surface soil organic carbon in different soil types is:latosolic red soil> latosol> payday soil> alluvial soil>coastal sand soil> torrid red soil.(3) The soil organic carbon densities are different if the soil types not the same. The analysis showed that the red soil organic carton density is10.34kg-m"2on average, the coastal sand soil organic carbon density is1.69kg-m"2on average, the volcanic dust organic carbon density is9.90kg-m"2on average, the paddy soil organic carbon density is5.55kg-m-2on average, the alluvial soil organic carbon density is5.03kg-m" on average, the torrid red soil organic carbon density is2.24kg-m" on average, the latosol organic carbon density is6.52kg-m"2on average, the purple soil organic carbon density is6.50kg-m"2on average. (4) The calculation in this study indicates that the latosolic red soil under research have31926391.99t of organic carbon, the coastal sand soil under research have1081205.39t of organic carbon, the volcanic dust soil under research have3790161.54t of organic carbon, the paddy soil under research have15421355.43t of organic carbon, the alluvial soil under research have1951797.44t of organic carbon, the torrid soil under research have1961040.26t of organic carbon, the latosol under research have118499636.67t of organic carbon, the purple soil under research have1603960.80t of organic carbon, in Hainan province.(5) From the analysis of the study we can find the distribution of organic carbon in Hainan province that from west to east of the increasing trend. There are lots of factor affect the distribution of soil organic carbon, but the influence degree of each impact factor is different, the main influence factors were oxygen-prone organic carbon, weight, total nitrogen and hydrolysis nitrogen, followed by viscous grain content and CEC, etc. Through the analysis of organic carbon and oxygen-prone organic carbon, total nitrogen, weight got the linear relationship between the equations.(6) The research found that the organic carbon density in central of Hainan province is higher than around, and the organic carbon density is gradually reduced from inside to outside.