Relationship between soil water content and soil particle size on typical slopes of the Loess Plateau during a drought year

Abstract

In the context of global climate change as well as local climate warming and drying on the Loess Plateau of China, understanding the relationship between soil particle size and soil water distribution during years of atypical precipitation is important. In this study, fractal geometry theory is used to describe the mechanical composition and texture of soils to improve our understanding of hydropedology and ecohydrology in the critical zone on the Loess Plateau. One grassland slope and two shrubland slopes were selected in the hilly and gully region of the Loess Plateau, and soils were sampled along hillslope transects at depths of 0-500 cm. Fractal theory and redundancy analysis (RDA) were used to identify relationships between the fractal dimension of soil particle-size distributions and the corresponding van Genuchten parameters for the soil-water-characteristic curves. The oven-drying method was used to measure soil water content, and the high-speed centrifugation method was used to generate soil-water-characteristic curves. The results show that (1) the soil water that can be used by Caragana korshinskii during a drought year is distributed below 2 m from the surface, whereas the soil water that can be used by grass is below 1.2 m; (2) Caragana korshinskii promotes the conservation of fine soil particles more than does natural restored grass, and the soil particle-size distribution fractal dimension changes with depth and position; and (3) soil hydraulic properties correlate strongly with soil pedological properties such as bulk density and the soil particle-size distribution fractal dimension. These results provide a case study of the relationships among soil distributions, hydrologic and geomorphic processes for vegetation restoration in drylands with a thick vadose zone. More studies on soil property changes are needed to provide case studies and empirical support for ecological restoration in the Loess Plateau of China.

Grazing and Cultivated Grasslands Cause Different Spatial Redistributions of Soil Particles

“…The distribution of soil particles is an important soil physical characteristic that affects soil hydraulic characteristics, soil fertility and soil erosion [28]. Changes in land use change the redistribution of different soil particle sizes to some extent [29], and different vegetation types also have a significant effect on the particle size distribution of different soil layers [30]. Our results showed that the percentage of greater than 53 µm soil particles significantly increased and the percentage of less than 53 µm soil particles significantly decreased with increasing cultivation age.…”

Effects of ecological restoration on soil properties of the aeolian sandy land around Lhasa, southern Tibetan Plateau

“…Soil organic matter is associated with primary mineral particles (i.e., sand, silt, and clay) in many soil types (Huang et al 2017). Many studies have found that fine particles, especially clay and silt, have high absorption capacity for soil organic carbon (Ye et al 2019, Zhang et al 2019b). The natural grassland (D), with higher silt content, tended to have a higher SOM content (Tables 2, 3).…”

Moisture Distribution in Sloping Black Soil Farmland during the Freeze–Thaw Period in Northeastern China

“…Often, only the conditions before and after the freeze-thaw cycles are considered [2][3][4]. As the data are not fine enough, the daily freeze-thaw cycle is missed every day during the daily data interval.…”