| The results indicated that under the same use mode of land, the content of agglomerate in farmland increased with the decrease of particle size. When the particle size was less than 0.25mm, the content was the largest. The particle size composition of agglomerate in land for different years was bimodal. When the particle size of the vegetable agglomerate is 1~2mm, the content of agglomerate is the largest. The aggregate content of the forestland decreased with the decrease of the particle size. In different soil layers, he aggregate content of particle size which is more than 5mm in farmland was the least in the surface layer, and the aggregate content of particle size which is more than 5mm in the wasteland was the most in the surface layer, and the content of vegetable agglomerates decreased with the increase of soil layer. The change of soil aggregates in forest land is more complicated. All of them indicate that human activities such as fertilization, trampling, weeding, etc.have obvious effects on larger particle size aggregates. The content of organic carbon in aggregates of different particle sizes was also different under different land use patterns. Generally, the organic carbon content of aggregates increased with the decrease of aggregate size. In addition, The organic carbon content of aggregates with a particle size less than 0.25 mm in farmland, abandoned land A, abandoned land B, abandoned land C, vegetable land and forest land is 2.78, 2.45, 3.71, 3.73, 4.08 and 2.92 times as much as the content with particle size of 5 mm, respectively. The difference of content is the largest, which indicates that in the changing process of land use, the accumulation and distribution , which is a sensitive part of the change in land use patterns, of organic carbon is the first part that can be impacted in aggregates with a particle size more than 5 mm. Under different land use modes, the organic carbon in the aggregates decreased in the following order, that is, vegetable land, farmland, woodland, abandoned land A, abandoned land B, and abandoned land C, indicating that the wasteland within 10 years is not conducive to the accumulation of organic carbon in aggregates. |
