Richards equation is widely used as the basis for simulations of water transport in soils. For infiltration into horizontal soil columns, Richards equation predicts that the water content profile is a unique function of the Boltzmann variable (distance)/(time), where q = 0.5. However, a number of experiments have found that q is significantly less than 0.5. Scaling with q < 0.5 is consistent with a generalized Richards equation that uses a fractional time derivative of the water content. In this paper we consider a generalized Richards equation that incorporates the unsaturated hydraulic conductivity function k(h) of van Genuchten (1980). A new method is proposed for estimating the van Genuchten parameters α and n. Estimates of α and n are expressed as closed form equations that are functions of other parameters such as the length of wetted zone, the sorptivity, and the saturated hydraulic conductivity.