The empirical equation w = asb was used to fit water holding capacity of four kinds of agricultural soils in loess plateau . soil water holding capacity and unavailable water content increased as soil texture became clayed . available water content in loam was higher than those in sandy soil and clayed soil 黄土高原四种主要农业土壤的水分特征曲线并无明显的平台或拐点产生，其关系能够很好地用garden经验方程( w = as ~ ( - b ) )进行拟合。
