局部覆盖条件下干旱过程对土壤水分蒸发的影响

采用旱棚人工控水、蒸发桶称重法,对地膜、渗水膜、干草、塑料泡膜4种地面覆盖材料在50%覆盖度下的土壤水分蒸发性能及保墒能力进行了研究。结果表明,4种透水或不透水覆盖材料均能有效减少土壤水分蒸发,其中蒸发抑制作用最强的为地膜,其次为渗水膜,塑料泡膜作用最小;在为期5个月的试验期间,地膜、渗水膜、干草、塑料泡膜覆盖可减少土壤蒸发量分别为23.04,10.89,10.03和5.68mm。试验还发现,覆盖材料对土壤蒸发的抑制能力与土壤干旱过程密切相关,低含水率持续干旱阶段土壤蒸发速率随蒸发历时延长而减小;高含水率干湿交替及持续干旱阶段则相反。局部覆盖能显著提高覆盖区与相邻非覆盖区的平均土壤含水率,延长适宜植物生长的土壤水分的持续期,减轻持续干旱对造林成活和幼林生长的威胁。

Influence of drought process on evaporation under partial mulching conditions

Based on natural evaporation experimentation with artificially controlled precipitation,the evaporation and soil moisture under 50% coverage rate with four types of mulching materials were studied.The results showed 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.Of 4 types of mulching materials including plastic film (PF),water permeable plastic film (WPPF),hay (Hay) and sponge plastic sheet (SPS),PF is very good,WPPF and Hay next,SPS relatively poor for inhibiting evaporation,and the inhibiting ability of mulching for soil evaporation is 23.04,10.89,10.03 and 5.68 mm respectively during 5-month period.With the increase 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 the mean soil moisture in the mulched area and adjacent uncovered area,lengthen the duration of soil moisture which was fit for plant growth,and lighten the threat of continuous drought to survival and growth of young forest.