局部覆盖条件下土壤水分移动性能与蒸发力的关系

Relationship Between Evaporation Potential and Movement Property of Soil Water under Partial-mulch Conditions

采用旱棚人工控水,蒸发桶整体称重法,对4种地面覆盖材料、50%覆盖度条件下,土壤水分蒸发与移动性能进行了研究。结果表明,在持续干旱时段,覆盖不仅改善了覆盖区土壤水分状况,而且强化了覆盖区与相邻非覆盖区下层土壤液态水的运移与再分布,提高了相邻非覆盖区下层土壤水分状况,有利于减轻持续干旱对造林成活和幼林生长的威胁。通过非线性参数拟合,首次求得了表征塑料地膜、渗水地膜、干草和塑料泡膜4种地面覆盖材料对土壤蒸发的阻抗特征参数,为建立不同覆盖材料在局部覆盖条件下的土壤蒸发量模型奠定了基础。同时也求得了依据常规水面蒸发和土壤湿度等资料计算黄绵土裸地蒸发量和局部覆盖条件下土壤蒸发量的经验模型。

Based on nature evaporation experimentation with artificial controlled precipitation, the evaporation and availability of soil water to plant under 50% cover rate conditions with four types of mulch materials, including plastic film, water permeable plastic film, hay and sponge plastic sheet, were studied. The results shown that the ability of mulching inhibiting soil evaporation not only relates to property of materials, but also relates to arid process caused by initial soil moisture and the distribution of rainfall. With increasing of duration, the soil evaporation rate decreases in the continuous drought period with low initial soil moisture and increase in the intermittent drying and wetting period with high initial soil moisture. Mulching can apparently enhance availability of soil water, lengthen the duration of available water, enhance redistribution of soil water from covered soil mass to adjacent bare soil mass, increase soil moisture in the adjacent bare soil mass, which can lighten threat of continuous drought to survival and growth of youngling. The most important things is that the characteristic impedance value of different mulch materials to evaporation were gotten at the first time, which lay the bases for establishing model to calculate evaporation of partially mulched soil. By the non-liner parameters improper, the experiential model was gotten for calculating evaporation of bare soil and partially mulched soil.