Abstract:The distribution of soil humus was studied under three soil types (yellow soil, purple soil and paddy soil) and four patterns of land use (paddy fields, dryland, orchard and tea garden), samples were collected in Mingshan River watershed. The results showed that the carbon content of three types of soil humus was between 9.74 and 21.66 g/kg, and the content of the surface soil (0-20 cm) was greater than that of the lower soil (20-40 cm), and the content followed the order of paddy soil>purple soil>yellow soil. The carbon content of paddy soil was significantly greater than those of purple soil and yellow soil. The carbon content of each humus component was significantly positively correlated (P<0.01). From the way of land use, the carbon content of paddy humus was significantly larger than that of orchard, tea garden and dry land, and it was significantly correlated with HA (P<0.01), and the degree of humification of soil was yellow soil>purple soil>paddy soil. The content of the recombinant carbon in different utilization modes was paddy field>orchard>tea garden>dry land. The ratio of the loose humus to the tight humus in the tea garden was the maximum (1.37), which was 2.14 times as high as that of the lower soil of the paddy field. The content of HA in the three types of soil aggregates was between 0.02 and 4.57 g/kg, and the content of the humic acid content decreased first and then increased with the decreasing of the particle size. Except for 2~5 and <0.25 mm aggregates, the aggregates with the sizes of >5, 1~2, 0.5~1 and 0.25~0.5 mm were positively correlated with HA content (P<0.05). In conclusion, soil humus composition was affected by soil types and artificial cultivation management activities. Paddy field soil fertility was the highest, and the content of HA was most affected by aggregates larger than 5 mm.