河西走廊不同土地利用方式下土壤团聚体组成与稳定性特征 postprint

Abstract: An understanding of soil aggregate composition and stability under different land-use types in the Hexi Corridor can reveal how soil structure responds to anthropogenic disturbances in arid regions and provides a scientific basis for soil quality assessment and sustainable land management.Four representative land-use types in the Hexi Corridor were selected:cropland,orchard,forestland,and grassland.Soil samples were collected from the 0-20 and 20-40 cm depth intervals.Wet sieving was employed to separate soil aggregates into the following four size fractions:>2,0.25-2,0.053-0.25,and mined,and aggregate stability indices were calculated,including mean weight diameter,geometric mean diameter,proportion of macroaggregates (R0.25),and the ratio of macroaggregates to microaggregates.Soil aggregate composition,stability,and their driving factors under different land-use types were analyzed.Across all land-use types in the study area,soil aggregates were dominated by the 0.25 mm fraction;the >2 mm and 0.25-2 mm fractions constituted relatively lower proportions.The mass proportions of the >2 mm and 0.25-2 mm aggregates were significantly higher at both soil depths in forestland compared with cropland and grassland,whereas no significant differences were observed among cropland,orchard, and grassland.Generally,aggregate stability followed the pattern of forestland >orchard >cropland >grassland. In the 0-20 cm layer,forestland exhibited significantly greater stability than all other land-use types.In the 20-40 cm layer,forestland was significantly more stable than cropland and grassland but did not differ significantly from orchard.However,within each land-use type,aggregate stability did not vary significantly between the two depth intervals.Correlation analysis indicated that aggregate stability was unrelated to soil pH but was positively correlated with soil organic matter and total nitrogen content.Overall,forestland in the Hexi Corridor exhibits significantly higher soil aggregate stability than cropland,orchard,and grassland;this is primarily due to the accumulation of soil organic matter and total nitrogen,which are key determinants of aggregate formation and stability in this region.