Characteristics of Soil Water, Salt and Nitrogen Distribution, and Accumulation on Forest Land, Cropland, Playa and Grassland in Bashang Area of Hebei Province

Abstract

[Objective] The distribution of soil water, salt and nitrogen in arid and semi-arid areas were analyzed in order to provide a basis for preventing and controlling non-point source pollution of groundwater and sustainably utilizing water and soil resources. [Methods] Four typical land use types (forest land, cropland, playa and grassland) in the Bashang area of Hebei Province were selected as the study objects. By analyzing changes in water, salt and nitrate of soils, we determined the distribution patterns of water, salinity, and nitrogen in the soil profiles of the different land use types. [Results] ① The soil water and salt content in the playa of Anguli Lake was the highest among the different land use types, with an average water content of 60.18%. The distributions of soil water and salt showed medium variability, with a greater degree of variability in water content. ② The same distributions of soil water and salt in the 0—220 cm soil profile were observed for forest land, farmland, and the playa (all except grassland) of Anguli Lake, exhibiting an oscillating shape, homogeneous shape, and bottom aggregation shape, respectively. ③ Saltions for the four land use types were significantly different (p<0.05), and their compositions were dominated by SO42-, while K+, Mg2+ and Ca2+ were relatively scarce. ④ The average nitrate content in the soil profile of the playa of Anguli Lake was as high as 134.18 mg/kg. Its distributions in forest land and farmland exhibited accumulation in topsoil, characterized by less in the middle and more at the top and bottom of the playa of Anguli Lake. The accumulation of nitrate in the upper soil layer of grassland was obvious. ⑤ The nitrate of soils of forest land, cropland, playa and grassland showed highly significant positive correlations with K+, which was the main factor that controlled the variation of nitrate. [Conclusion] The distributions of soil water, salt and nitrogen on forest land, cropland, playa and grassland in the Bashang area of Hebei Province had obvious variability, and the soil water, salt, and nitrogen content in the playa of Anguli Lake was significantly higher than seen for the other three land use types, thereby posing a serious risk of leaching to groundwater.

Keywords

• bashang area of hebei province
• land use
• soil water and salt
• nitrate
• groundwater pollution