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OA

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 sci-entific 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<0.053  mm.The mass proportions of each fraction were deter-mined,and aggregate stability indices were calculated,including mean weight diameter,geometric mean diame-ter,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<0.053  mm fraction,followed by the 0.053-0.25  mm fraction;the>2 mm and 0.25-2  mm fractions constituted relatively lower proportions.The mass pro-portions of the>2  mm and 0.25-2  mm aggregates were significantly higher at both soil depths in forestland com-pared 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 sig-nificantly higher soil aggregate stability than cropland,orchard,and grassland;this is primarily due to the accu-mulation of soil organic matter and total nitrogen,which are key determinants of aggregate formation and stabili-ty in this region.