Effects of soil morphology on hydraulic properties: II. Hydraulic pedotransfer functions

Pedotransfer functions (PTFs) have gained recognition in recent years as an approach to translate simple soil characteristics found in soil surveys in to more complicated model input parameters. However, existing pedotransfer functions have not Set incorporated critical soil structural information. T his study showed that soil hydraulic properties could be estimated from mor phological features determined in situ (including texture, initial moisture state, pedality, macroporosity, and root density) through a morphology qua ntification system. Comparison between the class and continuous PTFs develo ped in this study indicated that the use of quantified morphological proper ties yielded predictive power similar to that of physical properties in est imating hydraulic conductivity at zero potential; water now rates in macro- , meso-, and micropores: and a soil structure and texture parameter alpha(m acro). The results confirmed that soil structure was crucial in characteriz ing hydraulic behavior in macropore now region; whereas texture had major i mpact on those hydraulic properties controlled by micropores. Depending on the flow domain to be included, estimation of hydraulic properties required the use of different combinations of morphometric indices or physical prop erties. The PTFs established mag be used as starting points for estimating model input parameters.