Pedotransfer functions for the soil water characteristics of New Zealand soils using S-map information

The available data was split between a fitting and an independent validation dataset used for verification of the uncertainty model. Using the independent validation dataset, none of the models showed any evidence of over-fitting. The logit-transformation model was selected because it provided the lowest reliable estimate of mean absolute error and root mean square error in soil water response, TAW, and macroporosity, with uncertainty estimates based on posterior simulation. In the case of certain soil orders, a bias in the estimated TAW is evident at high values, although its origin is not clear. The selected model is used as the soil hydraulic response pedotransfer function used in the S-map inference engine to provide estimates of water content and available water for a wide range of New Zealand soils.