干旱半干旱地区双垄地布覆盖对土壤水分的影响

Effects of double ridge geotextile mulching on soil moisture in arid and semi-arid regions

为探明一种可替代覆盖材料的可行性,在甘肃省定西市安定区开展了为期1 a的监测试验,试验设防草地布加地膜覆垄(MB)、防草地布覆垄(DB)和裸地起垄(CK)3种处理,利用土壤水分、水势传感器分别对沟内地表下5、15 cm的土壤含水率、水势进行监测,结果表明:(1)表层5 cm土壤水分日变化呈复杂波形,受不同覆垄处理和季节性天气变化的影响显著;(2)0~20 cm土层的水分年变化主要受降雨、露水和蒸发强度的影响,表现为春冬干、夏秋湿的特点,在11月至翌年2月期间MB和DB覆垄处理土壤水分净损失量要高于CK裸地垄,而在作物生育期内(5-9月)覆垄处理土壤储水净增量为DB最大(36.35 mm)、MB次之(30.73 mm)、CK最小(16.30 mm);(3)MB和DB覆垄能明显加快雨露叠加,增加土壤水储存,而CK处理下叠加效应弱,且深层土壤对降雨不敏感,具有滞后性,但随着连续降雨的发生,表层土壤储水量加大,这种滞后性明显减弱;(4)0~20 cm土层土壤储水量日变化幅度为夏季最大(平均1.20 mm·d^-1),春季次之(1.03 mm·d^-1),秋季最小(0.79 mm·d^-1),全年水分净收获总量为DB最大(24.9 mm)、MB略低(21.5 mm)、CK最小(11.4 mm)。整体而言,只用地布覆垄具有最好的集水效果,这种防草地布可多年使用,无地膜碎片化污染问题,但在无降雨时期,垄沟内因土壤水分高,其蒸发强度略高于裸地处理。

In order to evaluate the feasibility of a substitute material-geotextile weed blocker,a one-year long monitoring experiment was carried out in Anding District,City of Dingxi,Gansu Province.The experimentation included three treatments:weed-blocking geo-textile fabric plus plastic film mulching on the ridge(MB),geo-textile fabric mulching on the ridge(DB),and bare soil ridge(CK).Soil moisture and water potential sensors were installed to monitor the changes in soil moisture content and water potential at 5 cm and 15 cm below the surface of the furrow.The results showed that:(1)Diurnal variation of moisture in top 5 cm surface soil was wave-like,which was significantly influenced by the ridge cover types and the seasonal climate changes.(2)The annual variation of water content in top 0~20 cm soil was mainly affected by rainfall,dew,and evaporation rates.It can be characterized as dry in spring and winter,and wet in summer and autumn.From November to February,the net loss of soil water in MB and DB was higher than CK,but during the crop growing season(May-September),the net gain of soil water storage was the highest in DB(36.35 mm),followed closely by MB(30.73 mm)and the lowest in CK(16.30 mm);(3)Ridge mulching under MB and DB obviously accelerated the superposition of rain and dew over the ridge so as to increase soil water storage in the furrow.This effect was weak under CK treatment,and the deep soil infiltration was less responsive to rainfall and dew,showing a lagging effect.But,with the occurrence of continuous rainfall,this lagging was obviously weakened due to higher water storage in the top layer;(4)The diurnal variation of 0~20 cm soil water storage was the largest in summer(average 1.20 mm·d^-1),medium in spring(1.03 mm·d^-1)and the smallest in autumn(0.79 mm·d^-1).The annual net harvest with different ridge covering measures was the highest with DB(24.9 mm),followed closely by MB(21.5 mm)and the smallest with CK(only 11.4 mm).Overall,ridge mulching using geotextile fabric alone had the best water harvesting effect.This weed-blocking fabric can be used for multiple years without fragmentation and soil pollution problems associated with plastic film mulching,but in the no-rain season,because of higher soil moisture in the furrow,its evaporation rate was slightly higher than the bare ridge treatment.