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土壤水分植被承载力是黄土高原生态环境建设和可持续发展的核心。该文根据陕北黄土区4种不同立地条件下苜蓿地(MedicagosativaL.)连续3a的降雨、径流、土壤水分动态和生物产量的小区定位观测结果,研究分析了自然降水与土壤水分补给、土壤水分补给与地上部生物量、地上部生物量与土壤水分消耗的关系;并采用FAO法和水量平衡法分别计算出了苜蓿地土壤水分的承载力。结果表明:苜蓿地土壤水分补给量与地上部生物量呈线性关系,地上部生物量与土壤水分消耗量呈二次函数关系。用FAO法估算可得陕北黄土区土壤水分可承载的苜蓿最大产量为3992.2～4173.7kg/hm2;而根据水量平衡原理计算可得陕北黄土区苜蓿地可承载的地上部生物量为2600～3500kg/hm2,比FAO法低16.07%～33.52%。坡向、坡位相同时,坡度增大,承载力降低;坡向、坡度相同时,下坡承载力大于上坡;坡度、坡位相同时,南坡承载力小于北坡。
The carrying capacity of soil water vegetation is the core of ecological environment construction and sustainable development in the Loess Plateau. Based on the results of cell location observation on the runoff, runoff, soil water dynamics and biomass of Medicagosativa L. for four consecutive years under four different site conditions in the Loess Area of the Loess Plateau, the effects of natural precipitation and soil moisture supply, soil moisture The relationship between recharge and aboveground biomass, aboveground biomass and soil water consumption. The soil moisture carrying capacity of alfalfa was calculated by FAO method and water balance method. The results showed that there was a linear relationship between the recharge of alfalfa and the aboveground biomass, and the quadratic functional relationship between aboveground biomass and soil water consumption. The maximum yield of alfalfa which can be carried by soil moisture in loess area of northern Shaanxi Province is 3992.2 ~ 4173.7kg / hm2, which is estimated by FAO method. According to the principle of water balance, the aboveground biomass of alfalfa land in Loess area in North Shaanxi is 2600 ~ 3500kg / hm2, 16.07% ~ 33.52% lower than the FAO method. When slope and slope are the same, the slope increases and the bearing capacity decreases. When the slope and slope are the same, the bearing capacity of descending slope is greater than that of ascending slope. When the slope and slope are the same, the bearing capacity of the southern slope is less than that of the northern slope.