地表覆盖对季节性冻融期土壤水分特征的影响

为探求不同地表覆盖下非饱和冻融土壤介质中土壤水分的迁移转化规律,于2013年11月10日~2014年3月22日在山西省晋中市东阳镇进行季节性冻融期系列田间试验。结果表明,地表覆盖有效地减少了地表土壤水分的蒸发,削弱了土壤含水率的波动幅度,但不同冻融阶段不同地表覆盖地块的土壤水分有所差异。与裸地(LD)相比,冻结阶段,秸杆覆盖(JG)和地膜覆盖(DM)显著增加了地表以下0~10cm土壤墒情,且DM比JG保墒效果好;融化前期,秸秆覆盖阻碍了融雪水的直接入渗,JG对土层的蓄水保墒作用不明显;融化后期,秸秆覆盖削弱了风速对地表土壤水分的影响,抑制了表土蒸发,对土层具有保墒作用。整个冻融期,DM始终对土层具有保墒作用,且其保墒效果较JG好。地表覆盖有效地减弱了地表以下0~20cm土壤含水率的波动幅度,随着土壤深度的加大,覆盖措施对土壤含水率的影响逐渐减弱。DM土壤水分随时间的变化态势与LD相似程度较高。从储水保墒角度出发,冻融期DM覆盖更具现实意义。研究成果可为北方冬春季节土地利用及管理提供指导。

Impacts of Surface Covering on Soil Water Characteristics during Seasonal Freeze-thaw Period

In order to study the migration and transformation of water in unsaturated soil under different surface cover conditions, the field tests of seasonal freezing-thawing for Dongyang town in Jingzhong City of Shanxi Province were carried out during November 10, 2013 to March 22, 2014. The results show that evaporation of soil moisture on the ground is reduced by the surface covering effectively and the fluctuation range of soil moisture content is also waken. But in different freezing-thawing stages, the soil moisture of land cover is different. Compare with LD, in freezing stage, JG and DM significantly increased soil moisture content below underground 0-10 cm, the soil moisture storage effect of DM is better than JG. In the early stage of melting, straw mulch blocked the direct infiltration of snowmelt water, the effect of JG on soil water conservation is not obvious. In the late stage of melting, straw mulching weaken the impact of wind speed on surface soil moisture, and restrained the evaporation of soil surface, the straw mulch has impact on soil moisture. In the whole freezing-thawing period, DM always has the role of soil moisture on soil water storage, water conservation and its effect is better than that of JG. Surface coverage effectively reduces the fluctuation range of soil moisture content below underground 0-20 cm, and with the increase of soil depth, the influence of surface mulching measures on soil moisture content gradually decreased. The variation trend of DM soil moisture with time is similar with that of LD. From the point of view of soil water storage, the DM covering during the freezing-thawing period is more practical. The research provides guidance for winter and spring seasonal land utilization and management in north region.