Contribution of soil macropores to water infiltration across different land use types in a desert–oasis ecoregion

Abstract

AbstractSurface soil hydraulic properties play critical roles in controlling water infiltration, evaporation, and soil water storage, in‐turn affecting the evolution of soil pore structure in cultivated desert soils of arid areas. The variability in soil pores and hydraulic properties caused by conversion of native semidesert soils to agroforestry use alters soil water storage and water budget in the desert–oasis ecotone. The objective of this study was to investigate that land use conversion alters surface soil hydraulic properties and enhances the contribution of soil macropores to water flow in the Linze desert–oasis ecoregion. Water infiltration and soil pores characteristics with nine replicates were measured using a disc tension infiltrometer across four habitat types (Haloxylon ammodendron shrublands, Populus gansuensis forests, Medicago sativa Linn grasslands, and Zea mays croplands) during the growing season. Soil properties and hydraulic conductivity characteristics clearly varied across the four habitat types. Saturated hydraulic conductivity was 0.177, 0.126, 0.118, and 0.031cm min−1 in the forest, grassland, shrubland, and cropland, respectively, with the corresponding average soil moisture being 7.6, 6.7, 0.9, and 19.2%. Clay content, bulk density, and initial soil moisture were the key soil physicochemical properties affecting saturated hydraulic conductivity (Ks). The macropores (> 0.5 mm in radius) accounted for 15–60% of total water flow, while 0.25–0.5 mm pores contributed to 12–24% across the four habitat types. The contribution of >0.5 mm pores to water flow in the forest was 3.3–4.0‐times greater than in shrubland and cropland, due to greater soil macroporosity (58 cm−3 cm3 ) and undisturbed soil pore structure. Land use conversion has a positive impact on soil properties, structure features, and soil hydraulic properties, and as a consequence, enhance the complexity of water exchange in the arid areas.