Hunan Soil and Fertilizer Institute, 730 Yuanda 2nd Road, Changsha, 410125, Hunan, China.
Key Laboratory of Agro-Ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha, 410125, Hunan, China.
Sci Rep. 2023 Jan 31;13(1):1773. doi: 10.1038/s41598-022-27244-1.
Cropland conversion has a major impact on soil C sequestration. However, it remains unclear about the changes in soil aggregate and their contribution to C accumulation following cropland conversion in a karst region, southwest China. In this study, three different cropland use types (sugarcane, mulberry and forage grass cultivation) were selected to replace maize-soybean cultivation. The soil was collected at a depth of 0 to 30 cm for analysis of soil aggregates and their OC content. Results showed that macro-aggregate was the predominant component underlying four cropland use types. Forage grass cultivation remarkably increased the OC stock and aggregate stability (MWD and GMD). OC content and stock associated with aggregate varied with cropland use types and soil depth, but were typically highest in forage grass fields. Macro-aggregates contained higher OC content and stock than other aggregate fractions, along with soil depth underlying four cropland use types. The increases in OC stock in forage grass field was mainly due to increased OC stocks within macro-aggregates, which is further attributed to the increase in OC content within macro-aggregates. Overall, forage grass cultivation replaced maize-soybean cultivation was suggested as an ecological restoration model to enhance soil C sequestration potential, owing to its role in increasing OC stock of aggregation and aggregate stability, in the karst region of southwest China.
耕地转换对土壤碳固存有重大影响。然而，在中国西南喀斯特地区，耕地转换后土壤团聚体的变化及其对碳积累的贡献仍不清楚。本研究选择了三种不同的耕地利用类型（甘蔗、桑树和牧草种植）来替代玉米-大豆种植。采集了 0-30cm 深度的土壤，用于分析土壤团聚体及其有机碳含量。结果表明，大团聚体是四种耕地利用类型的主要组成部分。与玉米-大豆轮作相比，牧草种植显著增加了有机碳储量和团聚体稳定性（MWD 和 GMD）。与耕地利用类型和土壤深度有关，但在牧草田通常最高。与其他团聚体部分相比，大团聚体中含有更高的有机碳含量和储量，四种耕地利用类型都有这种情况。在牧草田，有机碳储量的增加主要是由于大团聚体中的有机碳储量增加，这进一步归因于大团聚体中有机碳含量的增加。总体而言，在中国西南喀斯特地区，牧草种植替代玉米-大豆种植被认为是一种增强土壤碳固存潜力的生态恢复模式，因为它在增加团聚体的有机碳储量和团聚体稳定性方面发挥了作用。
