Luo Xiao-Hong, Wang Zi-Fang, Lu Chang, Huang Rong, Wang Fu-Hua, Gao Ming
College of Resources and Environment, Southwest University, Chongqing 400715, China.
Huan Jing Ke Xue. 2019 Aug 8;40(8):3816-3824. doi: 10.13227/j.hjkx.201812140.
The distribution and stability of soil aggregates under different land use types, and the distribution of organic carbon in various aggregates, were explored in order to provide a basis for the improvement of soil structure and the maintenance and improvement of soil organic carbon in Chongqing. Focusing on six representative subtropical land use types in the Beibei District of Chongqing (coniferous and broadleaf mixed forest, bamboo forest, orchard, dryland, paddy field, and waste grassland), soils were sorted using the wet sieving method and the six soil types were compared and analyzed. The distribution of aggregates and their organic carbon content were determined at soil profile depths of 0-20, 20-40, 40-60, and 60-100 cm for each land use type. The results showed that there were significant differences in soil structure and fertility levels under the different land use types. Among the particle size aggregates of the 0-100 cm soil layer, the aggregate particle size of the six land use types was mainly >0.25 mm; the content of >0.25 mm aggregate fraction of bamboo forest soil is the highest, followed by the grassland soil, and the dryland and orchard soils is the lowest. Granular aggregates in the size class 0.25-2 mm were mainly distributed in the 0-20 cm soil layers (28.78%-50.08%), while the aggregate size fractions 0.053-0.25 mm and<0.053 mm were mainly concentrated in the 40-60 cm soil layers. Across the entire profile depth, the aggregate MWD and GMD of the bamboo forest and barren grassland soils were higher than the other land use types, i. e., the soil aggregates in these soils were more stable. The stability of soil aggregates was significantly positively correlated with soil aggregate organic carbon content (=0.569, <0.01). In the 0-100 cm soil layer, the organic carbon content of soil aggregates was higher for the 0.25-2 mm and<0.053 mm fractions, with an average content of 56.54 g·kg in the 0.25-2 mm fraction. Except for the organic carbon content of the soil aggregates with different particle size of dryland was the highest in the 20-40 cm soil layer, while under the other land use types, the organic carbon content in soil aggregates decreased with depth, showing significant surface enrichment. Overall, under the six different land use types, the soil aggregates in bamboo forest soils and waste grassland soils showed good stability, and at each soil depth, the organic carbon content of aggregates was highest in the bamboo forest soil.
为了给重庆地区土壤结构的改良以及土壤有机碳的维持和提升提供依据，研究了不同土地利用类型下土壤团聚体的分布与稳定性，以及各团聚体中有机碳的分布情况。以重庆北碚区六种典型的亚热带土地利用类型（针叶阔叶混交林、竹林、果园、旱地、水田和荒草地）为研究对象，采用湿筛法对土壤进行筛分，并对六种土壤类型进行比较分析。针对每种土地利用类型，在土壤剖面深度0-20、20-40、40-60和60-100 cm处测定团聚体分布及其有机碳含量。结果表明，不同土地利用类型下土壤结构和肥力水平存在显著差异。在0-100 cm土层的粒径团聚体中，六种土地利用类型的团聚体粒径主要>0.25 mm；竹林土壤>0.25 mm团聚体组分含量最高，其次是草地土壤，旱地和果园土壤最低。粒径为0.25-2 mm的粒状团聚体主要分布在0-20 cm土层（28.78%-50.08%），而粒径为0.053-0.25 mm和<0.053 mm的团聚体组分主要集中在40-60 cm土层。在整个剖面深度上，竹林和荒草地土壤的团聚体平均重量直径（MWD）和几何平均直径（GMD）高于其他土地利用类型，即这些土壤中的土壤团聚体更稳定。土壤团聚体稳定性与土壤团聚体有机碳含量呈显著正相关（r=0.569，P<0.01）。在0-100 cm土层中，粒径为0.25-2 mm和<0.053 mm组分的土壤团聚体有机碳含量较高，0.25-2 mm组分的平均含量为56.54 g·kg。除旱地不同粒径土壤团聚体有机碳含量在20-40 cm土层最高外，其他土地利用类型下，土壤团聚体有机碳含量随深度降低，表现出明显的表聚性。总体而言，在六种不同土地利用类型下，竹林土壤和荒草地土壤中的土壤团聚体表现出良好的稳定性，且在各土壤深度处，竹林土壤团聚体的有机碳含量最高。
