Development of ensemble pedotransfer functions for cation exchange capacity of soils ofQingdao inChina

Abstract

AbstractSoil cation exchange capacity (CEC), which is considered to be an indicator of buffering capacity, is an important soil attribute that influences soil fertility but is costly, time‐consuming and labour‐intensive to measure. Pedotransfer functions (PTFs) have routinely been used to predict soilCECfrom easily measured soil properties, such as soilpH, texture and organic matter content. However, uncertainty in which one to select can be substantial as differentPTFs do not necessarily produce the same result. In this study, a total of 100 soil samples were collected from surface horizons (0–20 cm) in different regions of Qingdao City, China. Three ensemblePTFs (ePTFs), including simple ensemble mean (SEM), individually bias‐removed ensemble mean (IBREM) and collective bias‐removed ensemble mean (CBREM), were developed to reduce the uncertainty inCECprediction based on 12 published regression‐basedPTFs. In addition, a localPTF(LPTF) forCECwas also developed using multiple stepwise regression and basic soil properties. The performances of the threeePTFs were compared with those of the publishedPTFs andLPTF. Results show that the differences between the performances of the publishedPTFs were substantial. When the systematic bias of each publishedPTFwas removed separately, the prediction capability of thePTFs was increased. The performance ofLPTFwas significantly better than that ofSEM, but slightly worse thanIBREM. It is noted thatCBREMhad higher accuracy than all of the other methods. Overall,CBREMis a promising approach for estimating soilCECin the study area.