Abstract
Objective This study aims to explore and evaluate the soil quality under different land use types in Qingshui River Basin in gully regions of the Loess Plateau, and quantify its relationship with environmental factors. Method Taking 4 typical site types (agricultural land, forest land, orchard, and irrigated grassland) in the basin as the study site, and based on 9 soil physical and chemical property indicators including soil bulk density, soil mechanical composition, soil nutrient content (organic matter, total nitrogen, total phosphorus, total potassium, and available potassium), principal component analysis and correlation were used to establish a minimum data set (MDS), and the soil quality of different land use types was calculated according to the weighted summation index method. Result (1) The contents of organic matter and total nitrogen of each soil layer in the forest land were the highest among the 4 site types. In 0−20 cm soil layer, the bulk density and total phosphorus content of agricultural land were significantly higher than those of other land types (P＜0.05). In 0−20 cm soil layer, the available potassium content in forest land was significantly higher than that in other 3 land use types (P＜0.05). There was no significant difference in pH among different land use types. The content of organic matter decreased gradually with the increase of soil depth and showed a significant positive correlation with total nitrogen (P＜0.05). (2) MDS for soil quality index evaluation included bulk density, sand percentage and available potassium content. The soil quality of the 4 land use types from high to low was forest land, irrigated grassland, agricultural land, and orchard. The soil quality index increased with the increase of altitude. Conclusion The overall soil quality of Qingshui River Basin is good, and the soil quality of forest land and irrigated grassland is high, while the soil quality of agricultural land and orchard is relatively low. [Ch, 4 fig. 2 tab. 34 ref.]
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