Abstract:
Abstract: To promote development of the forestry and alleviate soil water depletion in forest land, a better understanding of the effects of different mulching patterns on soil moisture region, and further seeking reasonable soil conservation measures in loess hilly-gully are paramount important. As the severe soil water depletion existed in forest land in the semiarid area of the Loess Plateau, the soil water contents under 3 different mulching patterns in jujube orchard were measured using a neutron probe (CNC100 DR, ChaoNeng, China) that had been calibrated using standard methods. From March 2012 to October 2015, volumetric soil water content was measured 3 times per month. Measurements were made at the depth increment of 0.1 and 0.2 m in the 0-1 and 1-5 m soil layer, respectively. Meanwhile, the meteorological data were collected from meteorological station near the experimental plots. The objective of this study was to investigate the effects of mulching patterns on soil water loss in jujube orchard during dormancy period. The test plots were located at Yuanzhi Mount in Mizhi County, Shaanxi Province. The test plots were selected in the 11-aged dwarf close planting jujube forest in October 2011. Three level-terraces with similar slope and aspect were established on a hillslope. For each level-terrace, 4 treatments (straw mulching, plastic film mulching, gravel mulching, and bare land) were set to explore the effects of mulching patterns on soil moisture. The plot scale for 4 treatments was 2 m × 3 m and the area for each plot was thus 6 m2. The 20 cm wide and 5 m deep ditch all around each plot was excavated for each plot. To isolate the surrounding soil water and root on the test plot, about 1 mm thick plastic was used. There was no irrigation during the experiment. The thickness of the straw mulching was 10-12 cm, while the particle size of gravel mulching was 0.5-1.0 cm with a thickness about 5 cm. In the plastic film mulching treatment plot, the terrain around the trunk of jujube tree was lower than the surrounding soil. Furthermore, 1-2 cm gap between the trunk and the plastic film was maintained to make sure that the ground water could flow into the trunk and infiltrate to the soil. The results indicated that in growth period the soil water was at increasing stage on the whole, while the soil water exhibited a decreasing trend in dormancy period. Hence, dormancy period occupied a dominant role in causing soil water loss in jujube orchard. The soil water loss of bare land ranged from 85.64 to 92.34 mm, which was approximately 2.12 times greater than the rainfall of the corresponding period. The depth of soil water loss could reach 200 cm in local jujube orchard. In the vertical direction of soil profile (0-200 cm), the soil water loss gradually decreased with the soil depth. The soil water loss of straw mulching, plastic film mulching, and gravel mulching was 38.32, 50.56, and 40.48 mm lower than that of bare land, respectively. Therefore, mulching can promote the soil water movement from shallow to deep soil layer.