Effect of Gravel-Sand Mulch on Soil Water and Temperature in the Semiarid Loess Region of Northwest China

In the semiarid loess region of northwest China, the use of gravel and sand as a surface-mulching material has been an indigenous farming technique for crop production for over 300 years. A field and modeling study was carried out to quantify the effect of a gravel-sand mulch material on soil water and soil temperature in the semiarid loess region of northwest China. The field experiment (April 4, 2001-July 12, 2001) consisted of two treatments: (1)no surface mulching as a control, and (2)gravel-sand surface-mulching. The numerical model HYDRUS-1D was used in the research reported in this paper. The results showed that compared with the nonmulched condition the gravel-sand mulched field had a more favorable soil-water and temperature environment for plant growth. In the initial stage of watermelon growth, there was larger soil-water storage (3.8cm versus 1.9cm) and soil temperature (10.8 degrees C versus 6.2 degrees C) in the 0-20cm soil layer with the gravel-sand mulch. The mulch provided very beneficial water and temperature conditions for the germination of watermelon. The gravel-sand mulch improved soil-water conditions because it was effective in reducing evaporation and enhancing transpiration. The gravel-sand mulch also improved infiltration of rainwater. For the 0-20cm soil layers the average temperature in the gravel-sand mulch field was 1.0-5.3 degrees C larger than that in the no-mulch field. In the 20-40cm soil layer, the average temperature in the gravel-sand mulch was 0.3-3.7 degrees C larger than that in the no-mulch field. In the early stages of plant growth, plant roots primarily centralized in the 0-40cm soil layer, and the temperatures under the mulch were conducive to plant growth and development. The field and model results consistently showed the value of a gravel-sand mulch to provide warm, moist conditions for watermelon production in the semiarid loess region of northwest China. (C) 2013 American Society of Civil Engineers.