不同粒径砾石覆盖对宁夏干旱区土壤水分蒸发的影响

Effects of Different Particle Sizes of Gravel Cover on Soil Evaporation of Arid Land in Ningxia

为了探求宁夏中部干旱区最适宜的硒砂瓜覆砂粒径,以宁夏中卫南山台地区天然砂石为试材,采用蒸发器整体称重法,研究了不同粒径砾石覆盖对土壤水分蒸发的影响。结果表明：砾石覆盖可显著降低土壤水分的蒸发量;且覆盖砾石的粒径越小,土壤日蒸发量越少,土壤含水量越高;试验时间内,以4.0-5.0 cm粒径处理的土壤水分累积蒸发量最大（10.67 mm）,以0.7-1.0 cm粒径处理的土壤水分累积蒸发量最小（7.80mm）,但砾石粒径在1.5-4.0 cm范围内时,不同粒径砾石抑制土壤水分蒸发的效果差别不大。相关性分析结果表明：可用多项式方程Y=at^2＋bt来模拟土壤水分累积蒸发量随时间的变化,用指数函数方程Y=ae^bx来模拟土壤总蒸发量随砾石覆盖粒径的变化。

This study was conducted to explore the most suitable particle size of gravel mulching in selenium-contained watermelon field. The natural gravel from Nanshantai Region in Zhongwei City, Ningxia, was used as tested materials to determine how different particlesize gravel covering affects daily soil water evaporation with evaporator overall weighing method. The results show that the daily soil water evaporation capacity of the gravel-covering particle size from high to low was CK L5（4.0-5.0 cm） L4（3.0-4.0 cm） L3（1.5-3.0 cm）L2（1.0-1.5 cm）L1（0.7-1.0 cm）.With the increase of particle size of gravel covering, the daily soil water evaporation capacity increased gradually, and the soil water content reduce gradually. The soil water cumulative evaporation in differently particlesized gravel cover was significantly less than that of bare soil, and the soil water cumulative evaporation with gravel cover increased with the increase of the particle size. With the increase of test days, the difference of soil moisture cumulative evaporation capacity between L3（1.5-3.0 cm）和 L4（3.0-4.0 cm）decreased gradually. As the gravel size was 1.5-4 cm, the inhibition effect of different particle sizes of gravel on soil water evaporation was of little difference. The appropriate gravel particle size of 1.5-4 cm could be selected to prevent the loss of a large amount of moisture, with other comprehensive factors. And the exponential function equation Y=ae^bx could be used to simulate the soil total evaporation along with the change of particle size of the gravel cover, and the polynomial equation Y=at^2＋bt could be taken to simulate soil water cumulative evaporation changes over time.