Gravel–sand mulch for soil and water conservation in the semiarid loess region of northwest China

In the semiarid loess region of northwest China, the use of gravel and sand as mulch has been an indigenous farming technique for crop production for over 300 years. However, systematic studies concerning the effects of surface gravel–sand (mixed gravel and sand) covers on soil and water conservation are scarce. Based on previous studies, this study investigates the effects of gravel–sand mulch on hydrological processes, thermal properties, soil erosion and soil productivity as well as plant growth. In addition, this paper also provides a general idea of the principles and methods of management of the gravel–sand mulched fields (GSMF). The results of the study show that surface gravel–sand mulch provides a more favorable environment for plant growth than non-mulched fields in the highly erodible loess area of northwest China. Use of a gravel–sand mulch changes the hydrological process and improves soil productivity, which is effective in reducing evaporation and runoff, improving infiltration and soil temperature, checking wind and water erosion as well as enhancing biological activity and soil fertility.