黄土高原水蚀风蚀区坡地土壤水分季节变化及水分利用效率

Seasonal Variation of Soil Water Content and Water Use Efficiency in the Water-Wind Erosion Crisscross Region of the Loess Plateau

通过建立径流小区对黄土高原水蚀风蚀交错区3种典型植被措施下水量平衡进行定位观测研究,分析3种植被措施对土壤水分的季节变化与水分利用效率的影响。结果表明,整个生长季节内3种植被措施下土壤表层5cm温度显著低于空气温度;土壤表层0-6cm水分季节性波动受到降雨的强烈影响。3种植被措施对剖面土壤水分季节变化产生显著影响,5-7月份为土壤水分消耗期,8-10月份为土壤水分补偿期。土壤垂直剖面含水量从表层到深层表现为先增加后减小再增加的趋势。3种植被措施对相同地形部位土壤水分所造成的差异不同,同一植被的土壤水分在不同地形部位也有差异。坡耕地(当年种植绿豆)径流系数为0.238,显著高于撂荒地与苜蓿地。3种植被措施下生物产量、水分利用效率均达到显著差异水平(p<0.05)。紫花苜蓿水分利用效率分别是绿豆、绿豆籽粒水分利用效率的1.9倍和8.3倍。坡耕地退耕还草或者建设人工植被等措施增强了对径流的拦蓄作用,具有较好的水土保持效应,同时提高了植物水分利用效率。

By establishing the runoff plots of three vegetation we carried on the site-specific observation on the soil moisture in the water-wind erosion crisscross region on the Loess Plateau,and analyzed the effect on seasonal variation of soil moisture and water use efficiency.Results showed that soil temperature at 5 cm depth was significantly below air temperature during the growing season;seasonal fluctuations of soil surface moisture at 0-6 cm depth was influenced by the temporal pattern of rainfall.Vegetation had a significant impact on seasonal variation of soil deep moisture（p0.05）.Soil moisture was consumed from May to July and compensated from August to October.Soil moisture from the soil surface to the vertical section increased firstly,then reduced,and increased again.Vegetation had different influence on soil moisture of the same terrain parts,and the soil moisture of the same vegetation at different terrain parts also had significant difference.Mung bean land runoff coefficient was 0.238,and it was significantly higher than abandoned land and alfalfa land.Hay yield and water use efficiency under vegetation significantly reached difference level（p0.05）.Water use efficiency of alfalfa was 1.9 times more than that of mung bean and 8.3 times of mung bean kernel.Grain for green program significantly increased surface runoff infiltration and had good soil and water conservation effects.Meanwhile it improved water use efficiency of vegetation.