Response of soil infiltration and water to orchard mulching practices in the Loess Plateau, China

Mulching practices, widely applied in arid and semi-arid areas, regulates terrestrial hydrological processes in agricultural soils. However, the mechanism by which mulching practices influence soil infiltration and water on the Loess Plateau remains unclear. Field experiments were conducted in October 2022 to investigate the variations in soil infiltration capacity and water storage under different mulching practices: straw mulching, rape intercropping mulching, and conventional tillage. Compared to conventional tillage, straw mulching showed faster infiltration rates both in topsoil and subsoil, whereas rape intercropping mulching had lower subsoil infiltration rates. Soil moisture replenishment was 25.4 % higher in the topsoil and 10.2 % higher in the subsoil under straw mulching. A porous soil structure, stable aggregates, abundant organic matter, and roots improved the infiltration capacity, whereas biocrusts impeded infiltration. Owing to the different traits of plough pan between treatments, subsoil had great effect (49.3 %) on topsoil infiltration changes. Straw mulching showed 18 % higher soil water storage (p < 0.05) at 0-100 cm depth, whereas rape intercropping mulching did not result in significant changes (p > 0.05). Both tillage frequency and understory biomass can indirectly affect soil infiltration and water storage by impacting the bulk density, porosity, aggregates, and organic matter. Understory biomass can also directly affect soil water storage by regulating rainfall distribution and reducing evaporation. These findings offer new insights into soil hydrological processes in agro-ecosystems of arid areas.