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研究土地利用方式对深剖面土壤水分时空动态的影响,对于了解区域水循环在变化环境下的表现特征具有重要意义.本研究基于长期定位监测数据,对2012年9月至2015年12月黄土塬区4种土地利用方式0~15 m剖面土壤水分状况进行分析.结果表明:苜蓿草地(>7年)、休闲地、高产农田和低产农田平均土壤含水量分别为15.1%、22.0%、19.6%和21.1%(0~15 m、年度平均值);干湿交替层季节性失水和蓄水分别出现在3—6月和7—10月,其深度范围分别为0~2、0~4.6、0~3和0~4.2 m.深层土壤水分具有较好的时间稳定性,其垂直分布受土地利用方式的影响.观测年份内苜蓿产量和耗水量均呈逐年增加趋势,造成深层土壤的干燥化程度加大,2~10 m土层形成稳定土壤干层,阻断了降水补给地下水的途径.对于其他3种土地利用方式下的土壤水分平衡,冬小麦生长季农田与休闲地均表现为负平衡;玉米生长季高产农田表现为负平衡,而低产农田与休闲地表现为正平衡;在作物休闲期,农田与休闲地均表现为正平衡.通过施肥处理所形成的高产农田的作物水分利用效率是低产农田的3倍以上.
Studying the effect of land use patterns on spatio-temporal dynamics of soil moisture in deep sections is of great significance for understanding the performance characteristics of regional water cycles in changing environments.Based on the long-term monitoring data, this study analyzed the spatial and temporal dynamics of soil moisture in the Loess Plateau from September 2012 to December 2015 The results showed that the average soil water content of alfalfa grassland (> 7 years), fallow land, high yield farmland and low yield farmland were 15.1%, 22.0%, 19.6% and 21.1% (0 ~ 15 m, annual average). Seasonal water loss and water storage occurred in alternating wet and dry layers in March-June and July-October, respectively, with depths ranging from 0 to 2,0 to 4.6, 0 ~ 3 and 0 ~ 4.2 m. The deep soil moisture had good time stability and its vertical distribution was affected by the land use patterns. The production and consumption of alfalfa increased year by year in the observation year, resulting in the desiccation of deep soil The soil layer in 2 ~ 10 m soil layer formed a stable layer of dry soil, blocking the way of rainfall recharge groundwater.For the other three kinds of land use patterns of soil moisture balance, winter wheat growing season showed negative balance between farmland and leisure ; Corn growing season high yield Field showed negative balance, while low-yield farmland and leisure field showed a positive balance; during crop fallow, both farmland and leisure field showed a positive balance. The crop water use efficiency of high yield farmland formed by fertilization was low yield farmland Times more.