Study On SOC Distribution And Storage In Purple Paddy Soil In Different Scale

Soil organic carbon (SOC) was characterized by high spatial variability. Its impact factor and various rules would change in different research scales. Conservative agricultural practices such as no-tillage, reasonable cropping system, and fertilization could influence soil physical and chemical characters, plant growth, quality and quantity of stubble, and soil microbial biomass and its activity, and hence maintain and increase soil carbon concentration. Despite of argument on the general SOC loss, an increasing trend of SOC in paddy soil had been evidenced by many pilot experiments and statewide soil survey data since 1980's in China. Nevertheless, less was understood on SOC distribution in paddy soil of region and their change in response to agricultural practices, soil fertility evolution and environmental stresses. Uncertainty of accumulation effect in regional paddy soil was sill in debt. The results from research on the distribution of SOC in soil aggregates, profile, farmland and regional scales can be showed.1. High content of aggregates in size of 0.25 ~ 0.02mm was possible characteristics of the distribution of soil aggregates in purple paddy soil, accounting for over 42%. The SOC content in aggregates of every treatment showed as a single-peak distribution. There was the highest content of SOC in aggregates in size of 2~0.25mm. From the viewpoint of total organic carbon content, the organic carbon was mainly found in aggregates in size of 0.25~0.02mm and 0.02—0.002mm secondly. The difference among the distributions of organic carbon in aggregates in profile was obvious. The distribution of organic carbon in aggregates in size of 2~0.25mm was most closed to the distribution of total carbon content, and the result showed these grains were the main component.2. SOC distribution in soil profile was similar to that of wash growth profile. The SOC content decreased steadily from top to bottom. There is a positive correlation between the SOC content and the clay content, to some extension. The varieties of soil particulate content was remarkable .affected by human activities(Such as plant orders , rotations, cultivation and management practices etc.). Soil particle composition distribution in soil profile in No-tillage and ridge culture had obvious varieties...