The distribution of soil organic carbon was studied under different soil types and land use patterns

samples were collected in Mingshan River watershed and analysed in the laboratory. The results showed as follows: (1) Organic carbon content of the three types of soil was 17.50-34.70 g/kg

and followed the order of paddy soil > yellow soil > purple soil; From the way of land use

the content of paddy soil organic carbon and active organic carbon were significantly higher than those of the dry land

tea gardens and orchards

soil active organic carbon and soil organic carbon were significantly positively correlated (R2 = 0.884 6). (2) The content of organic carbon of soil decreased gradually with the increase of soil depth. Soil organic carbon content showed the order of paddy soil > yellow soil > purple soil at the depth of 0-20 cm

and paddy soil > purple soil > yellow soil at the depth of 20-40 cm

and active organic carbon showed a similar pattern. (3) Under different land use patterns

organic carbon content in the surface soil followed the order of paddy field > dry land > tea garden

and that in the subsoils (20-40 cm) was in the order of paddy field > tea garden > dry land. Active organic carbon contents in both in the upper and the lower layers of the paddy field were significantly higher than those of the dry land

orchard and tea garden. It is proved again that active organic carbon is one of the important indicators of organic carbon. (4) Organic carbon content of soil aggregates decreased with the increase of soil depth

at the same time

the organic carbon content of soil aggregates showed a wavy changing trend with the decreasing particle size. Organic carbon content of soil aggregates was positively correlated with total soil organic carbon content. In conclusion

organic carbon contents in the soil and soil aggregates of different particle sizes were influenced by soil types and different utilization pattern

the distribution characteristics of organic carbon in the soil and soil aggregates were different.