title: Extrapolative capability of two models that estimating soil water retention curve between saturation and oven dryness.
abstract: Accurate estimation of soil water retention curve (SWRC) at the dry region is required to describe the relation between soil water content and matric suction from saturation to oven dryness. In this study, the extrapolative capability of two models for predicting the complete SWRC from limited ranges of soil water retention data was evaluated. When the model parameters were obtained from SWRC data in the 0-1500 kPa range, the FX model (Fredlund and Xing, 1994) estimations agreed well with measurements from saturation to oven dryness with RMSEs less than 0.01. The GG model (Groenevelt and Grant, 2004) produced larger errors at the dry region, with significantly larger RMSEs and MEs than the FX model. Further evaluations indicated that when SWRC measurements in the 0-100 kPa suction range was applied for model establishment, the FX model was capable of producing acceptable SWRCs across the entire water content range. For a higher accuracy, the FX model requires soil water retention data at least in the 0- to 300-kPa range to extend the SWRC to oven dryness. Comparing with the Khlosi et al. (2006) model, which requires measurements in the 0-500 kPa range to reproduce the complete SWRCs, the FX model has the advantage of requiring less SWRC measurements. Thus the FX modeling approach has the potential to eliminate the processes for measuring soil water retention in the dry range.
authors.affiliation: Key Laboratory of Tree Breeding and Cultivation of the State Forestry Administration, Research Institute of Forestry, Chinese Academy of Forestry, Beijing 100091, China; Collaborative Innovation Center of Sustaintable Forestry in Southern China, Nanjing Forestry University, Nanjing 210037, China.
authors.forename: Sen
authors.initials: S
authors.lastname: Lu
authors.affiliation: Department of Soil and Water, China Agricultural University, Beijing 100193, China.
authors.forename: Tusheng
authors.initials: T
authors.lastname: Ren
authors.affiliation: Department of Soil and Water, China Agricultural University, Beijing 100193, China.
authors.forename: Yili
authors.initials: Y
authors.lastname: Lu
authors.affiliation: Key Laboratory of Tree Breeding and Cultivation of the State Forestry Administration, Research Institute of Forestry, Chinese Academy of Forestry, Beijing 100091, China; Collaborative Innovation Center of Sustaintable Forestry in Southern China, Nanjing Forestry University, Nanjing 210037, China.
authors.forename: Ping
authors.initials: P
authors.lastname: Meng
authors.affiliation: Institute of Agro-resources and Environment, Hebei Academy of Agriculture and Forestry Sciences, Shijiazhuang 050051, China.
authors.forename: Shiyou
authors.initials: S
authors.lastname: Sun
mesh_terms: D055864:Droughts; D008962:Models, Theoretical; D012987:Soil / Q000737:chemistry*; D014867:Water / Q000737:chemistry*
chemical_list: D012987:Soil; D014867:Water