Abstract:
The quaternary ancient Red soils under different land use patterns including woodland, sparse forest grassland, grassland, cultivated land, and ancient Red soils buried by loess were investigated. The soil organic carbon and aggregate associated organic carbon content of ancient Red soils were determined to address the soil organic carbon distribution with soil depth. The soil aggregate associated organic carbon content of ancient Red soils under different land use patterns were compared to the ancient Red soil buried by loess. The content of soil organic carbon in the ancient Red soil buried by loess was low and distributed uniformly with depth. The soil aggregate associated organic carbon content of the ancient Red soil buried by loess decreased with the decreasing of aggregate size. The ancient Red soils exposed to surface and influenced by different land use patterns had accumulated soil organic carbon in the surface horizon. The soil organic carbon content of ancient Red soils was the highest for woodland, followed by that of cultivated land and sparse forest grassland, and the lowest for the grassland. The soil organic carbon content of woodland was significantly higher than that of other land use patterns, indicating the woodland was an optimal land use pattern in the area of ancient Red soils. Except for the 0-10 cm depth in cultivated land, the organic carbon content of > 0.25 mm aggregates decreased gradually with the decreasing of aggregate size, and that of < 0.25 mm aggregates increased gradually with the decreasing of aggregate size. The soil organic carbon content of > 1 mm and < 0.25 mm aggregates increased gradually with the decreasing of aggregate size, and that of 1 - 0.25 mm aggregates decreased gradually with the decreasing of aggregate size in the 0 - 10 cm depth under cultivated land.