在毛乌素沙地东南缘风沙滩区进行为期1年的野外连续定位观测试验，设置3组覆垄沟渗处理，即地膜加防草地布覆垄（MB）、防草地布覆垄（DB）和无覆垄空白对照（CK）。利用MPS-6水势温度传感器监测沟表下5，15，30 cm深度30 min间隔的土壤水势和土壤温度。结果表明：（1）3组处理的土壤水势日变化均呈现余弦曲线变化特征，在5 cm土层处土壤水势日变幅较大，土壤水势值为-600~-120 kPa，呈MB > CK > DB；在15 cm土层处，土壤水势较高且变幅较小，变化在-180~-90 kPa，呈DB > CK > MB；在30 cm土层处，土壤水势保持基本稳定，MB与DB处理的水势较高，稳定在-100 kPa左右，CK较低，稳定在-285 kPa左右；（2）土壤水势年内变化存在2个低谷，主要发生在土壤水处于冻结状态的冬季和蒸发强烈的夏季；3组处理土壤水势年均值表现为：5 cm处，MB > CK > DB；15 cm处，DB > CK > MB；30 cm处，MB=DB>CK，主要原因是覆盖条件下，白天土壤积温较高，夜间向上的温度梯度大，15 cm处土壤水分上移速度较快，地表膜布下积水，无膜布则蒸发，故表现为地表以下5 cm处MB水势较大，15 cm处水势较小；同时，MB条件下降雨入渗量最大，表层水分大；30 cm处MB和DB条件下，水势近似相同，但都大于裸地，主要原因是该地区降雨量较小，大部分降雨在无覆盖条件下不能下渗至30 cm处；（3）3组处理在0—30 cm土层，冻融期土壤水势受大气相对湿度及风速影响较大，非冻融期土壤水势受风速影响最大，其次是大气温度与相对湿度。试验表明5 cm土层MB保湿效果更好，而15 cm土层DB的保湿效果更好，30 cm土层MB和DB条件下水势接近，此结果可为沙漠地区固沙和植被恢复提供参考。
A one-year continuous field monitoring study at fixed observation positions was conducted on a sand belt site in the southeast edge of Mu Us desert land,with continuous monitoring of soil water potential and temperature. With the sand surface first reshaped into furrow-and-ridge form,the in-situ field test had 3 treatments,i.e.,the ridge section one was covered with plastic membrane plus weed-blocking geotextile (MB); section two covered with weed-blocking geotextile only (DB); and section three exposed or uncovered to serve as the blank contrast (CK). Soil water potential and temperature were monitored using MPS-6 probes at 5,15,30 cm below the furrow surface,at 30 minute intervals,along with meteorological data above the soil surface. Results showed that: (1) The daily variations of soil water potential under the 3 treatments all showed characteristics of a Cosmic function,the daily soil water potential at the 5 cm depth was the most varied in the three groups,varying between -600 and -120 kPa,and showing MB > CK > DB. At the 15 cm depth,the value was higher with smaller variation between -180 and -90 kPa,showing DB > CK > MB. At the 30 cm depth,the soil water potential is virtually stable,with high water potentials for MB and DB stabilized at about -100 kPa,and much lower stable potentials for CK at about -285 kPa; (2) The annual variation of soil water potential showed two valleys,including the freezing-thawing period in the winter and the strong evaporation period in the summer. The annual averages among the 3 groups show that: at 5 cm MB > CK > DB,at 15 cm DB > CK > MB,and at 30 cm MB=DB>CK. The main reasons are that under the condition of MB and DB,the accumulated heat in the soil during the day time is higher,and the upward temperature gradient at night is higher,then the soil water at 15 cm depth moves up and accumulates under the surface membrane and it would be evaporated without the membrane. Therefore,the water potential at 5 cm below the surface is larger,while the water potential at 15cm is smaller. At the same time,under the condition of MB,the rainfall infiltration depth is the largest,so is the surface water content; Under MB and DB conditions at 30 cm,the water potential is approximately the same,but both are larger than that under CK. The predominant reason is that the rainfall in this area is small,and most rainfall cannot infiltrate to 30 cm depth without mulching; (3) When the 3 groups were analyzed for the total 0-30 cm soil layer,the soil water potential was greatly affected by relative humidity and wind speed of the atmosphere during freezing-thawing period. In the non-freezing-thawing period,soil water potential was most influenced by wind speed,followed by atmospheric temperature and relative humidity. It can be concluded that the moisture retention effects at 5 cm soil depths was better with MB treatment,while DB was better for 15 cm soil depth,and both MB and DB were better for 30 cm soil depth. These results could be used as a reference for sand fixation and revegetation in the desert area.
任涛, 贾志峰, 王智, 钟哲.毛乌素沙地地膜—地布覆盖下土壤水势动态[J].水土保持学报,2020,34(4):78~84复制