地下滴灌苜蓿地土壤水分分布规律

The distribution rules of soil water in alfalfa field with subsurface drip irrigation

本文在地下滴灌条件下开展苜蓿田土壤水分分布规律的研究,以期为苜蓿高效节水生产提供理论依据。试验设置11个压力处理,研究工作压力对滴头流量的影响;设置600、750和900m3·hm-2 3个灌溉量处理,研究土壤湿润体入渗规律及土壤水分再分布规律。结果表明,滴头流量随工作压力增加而增大,呈对数函数关系;灌溉初期湿润体形状呈近似球体,灌溉30min后变为垂直地面方向狭长的椭球体,120min后呈开口较小,中部凸起、下部略尖的坛状,3种灌溉量下土壤湿润体形状相似,但湿润体入渗深度随灌溉量增加而增大。灌溉停止48h后不同土层土壤水分分布不均,垂直方向上,水分主要分布在0-30cm土层;水平方向上,随与滴灌带距离增大土壤含水率呈递减趋势,不同灌溉量比较表现为水平距滴灌带10cm处,0-50cm土层随灌溉量增大土壤含水率呈增加趋势,50-70cm土层无明显规律,水平距滴灌带20和30cm处各土层土壤含水率与灌溉量之间也无明显规律。

The experiment was conducted in the alfalfa field to study the soil water content distribution after the subsurface drip irrigation,in order to provide some theoretical references for the application of subsurface drip irrigation in alfalfa cultivation.Eleven pressure treatments and three irrigation amounts（600,750 and 900m^3·ha^-1）were set to evaluate the effect of the different work pressures on the dripper discharge and the effects of the irrigation amounts on the soil water infiltration and redistribution from the horizontal and vertical level.The results showed that dripper discharge increased with work pressure increasing which had logarithmic function relationship.The shape of soil wetting front changed with the time of irrigation which was approximate sphere within 30 minutes of irrigation,and was ellipsoid after 30 minutes,and then was Tan-shape after 120 minutes of irrigation.The vertical wetted depth increased with the irrigation amount which had a logarithmic relationship.There were significant differences among soil water content of seven layers（P〈0.05）after 48 hof irrigation.The 0-30 cm layer had the higher soil water content than the other layers in vertical direction.The soil water content decreased with the distance increase from drip irrigation belt in horizontal direction.The soil water content increased with increase of the irrigation amount at 0-50 cm layer of 10 cm sampling point,other sites had no obvious relationships between soil water content and irrigation amount.