Development of pedotransfer functions for predicting the bulk density in the critical zone on the Loess Plateau, China

Purpose The bulk density (BD) is an important physical property of soil, which is used to estimate soil carbon/nutrient reserves, and it is an important parameter in various predictive and descriptive models. However, BD data are lacking due to the difficulty of measuring it directly. Pedotransfer function (PTF) may provide an alternative method for estimating BD indirectly based on easily measured soil properties. The Loess Plateau in China (620,000 km2) has deep loess deposits (50–200 m), which makes it difficult to obtain BD values for the deep soil layer, and thus, a PTF is needed for estimating BD.