College of Resources and Environment, Northeast Agricultural University, Harbin 150030, China.
Ying Yong Sheng Tai Xue Bao. 2024 Jul 18;35(7):1815-1824. doi: 10.13287/j.1001-9332.202407.012.
Exploring the physical fractions of organic carbon and influencing mechanisms in grassland, forest, and farmland soils in wind erosion area can provide scientific basis for carbon sequestration, land utilization, wind prevention measure making, and fertility restoration of sloping farmland in the region. We examined the differentiation of aggregate organic carbon and density fractionation organic carbon in 0-15 cm soil layer across grassland, forest, and sloping farmland with 350 m long and 5° slope gradient in the wind erosion area of Meilisi District, Qiqihar, Heilongjiang, as well as the sloping farmland in the downhill section, middle section, and uphill section with every 100 m apart from the bottom to the top. The results showed that soil aggregates >2 mm were all destroyed across grassland, forest, and farmland soils, while the percentage of aggregates <0.053 mm was significantly higher than that of other sizes. The percentage of various soil aggregates, organic carbon content from density fractionations, and the proportion of organic carbon in the heavy fraction aggregates in farmland were significantly lower than that in grassland and forest soils. Soil aggregates in the uphill section of farmland were completely destroyed, and organic carbon content in various size aggregates and density fractionations gradually decreased with increasing slope. The proportion of organic carbon in the heavy fraction aggregates decreased, but that in light fraction aggregates increased gradually. Soil organic carbon and available potassium were key factors affecting aggregate stability, aggregate organic carbon content, and organic carbon content in density fractionations, while the loss of organic carbon in aggregate led to a decrease in aggregate stability. In summary, compared with grassland and forest soils, the stability of soil aggregates, the aggregate organic carbon content, the organic carbon content in density fractionations, and the proportion of organic carbon in heavy fraction aggregates in farmland all decreased in the wind erosion area of Northeast China. With the increases of slope, the aggregate organic carbon content, the organic carbon content in density fractionations, and the proportion of organic carbon in the heavy fraction aggregates in sloping farmland all decreased. Planting trees, conserving and expanding grassland area, and increasing the application of organic materials in sloping farmland in wind erosion area are effective approaches to stabilize and increase carbon storage, improve soil structure, and enhance soil quality.
探讨风蚀区草地、林地和农田土壤中有机碳的物理分异及其影响机制，可以为该区域的碳固存、土地利用、防风措施制定和坡耕地肥力恢复提供科学依据。本研究以黑龙江省齐齐哈尔市梅里斯区 350 m 长、5°坡度的风蚀区草地、林地和坡耕地，以及坡耕地从坡底到坡顶每隔 100 m 的下坡段、中段和上坡段为研究对象，分析了土壤团聚体有机碳和密度分级有机碳的分异，并探讨了土壤团聚体有机碳和密度分级有机碳与土壤物理性质的关系。结果表明：草地、林地和农田土壤中>2 mm 的土壤团聚体全部遭到破坏，而<0.053 mm 的团聚体比例明显高于其他粒径大小的团聚体。农田土壤中各粒径大小的团聚体、密度分级有机碳含量和重团聚体中有机碳的比例均显著低于草地和林地土壤。农田上坡段土壤团聚体完全遭到破坏，且随着坡度的增加，各粒径大小团聚体和密度分级中的有机碳含量逐渐降低。重团聚体中有机碳的比例减小，而轻团聚体中有机碳的比例逐渐增加。土壤有机碳和速效钾是影响团聚体稳定性、团聚体有机碳含量和密度分级中有机碳含量的关键因素，而团聚体中有机碳的损失导致团聚体稳定性降低。综上所述，与草地和林地土壤相比，中国东北地区风蚀区农田土壤团聚体稳定性、团聚体有机碳含量、密度分级有机碳含量和重团聚体中有机碳的比例均降低。随着坡度的增加，坡耕地的团聚体有机碳含量、密度分级有机碳含量和重团聚体中有机碳的比例均降低。在风蚀区种植树木、保护和扩大草地面积以及增加坡耕地有机物料的施用量，是稳定和增加碳储量、改善土壤结构和提高土壤质量的有效途径。
