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

摘要

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 (3.8 cm versus 1.9 cm) and soil temperature (10.8℃ versus 6.2℃) in the 0-20 cm 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 0-20 cm soil layers the average temperature in the gravel-sand mulch field was 1.0-5.3℃ larger than that in the no-mulch field. In the 20-40 cm soil layer, the average temperature in the gravel-sand mulch was 0.3-3.7℃ larger than that in the no-mulch field. In the early stages of plant growth, plant roots primarily centralized in the 0-40 cm 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.