Pedotransfer functions in Earth system science: challenges and perspectives

Authors: VAN LOOY, K - Juelich Research Center; BOUMA, JOHAN - University Of Wageningen; HERBST, M - Juelich Research Center; KOESTEL, JOHAN - Swedish University Of Agricultural Sciences; MINASNY, BUDIMAN - University Of Sydney; MONTZKA, CARSTEN - Swedish University Of Agricultural Sciences; NEMES, ATTILA - Norwegian Institute Of Bioeconomy Research(NIBIO); Pachepsky, Yakov; PADARIAN, J - University Of Sydney; SCHAAP, MARCEL - University Of Arizona; TOTH, BRIGITTE - University Of Pannonia; VERHOEF, ANNE - University Of Reading; VANDERBORGHT, JAN - Juelich Research Center; VAN DER PLOEG, MARTINE - University Of Wageningen; WEIHERMULLER, LUTZ - Juelich Research Center; ZACHARIAS, STEFEN - Helmholtz Centre For Environmental Research; ZHANG, Y - University Of Arizona; VEREECHEN, HARRY - Juelich Research Center

Submitted to: Reviews of Geophysics
Publication Type: Review Article
Publication Acceptance Date: 11/3/2017
Publication Date: 12/28/2017
Citation: Van Looy, K., Bouma, J., Herbst, M., Koestel, J., Minasny, B., Montzka, C., Nemes, A., Pachepsky, Y.A., Padarian, J., Schaap, M., Toth, B., Verhoef, A., Vanderborght, J., Van Der Ploeg, M., Weihermuller, L., Zacharias, S., Zhang, Y., Vereechen, H. 2017. Pedotransfer functions in Earth system science: challenges and perspectives. Reviews of Geophysics. 55(4):1199-1256.

Interpretive Summary: Earth sciences widely use modeling. All models include parameters of soil processes, i.e. coefficients to relate different soil variables and compute process rates. Many parameters cannot be measured directly and need to be estimated from readily available soil data. Rules of such estimation are called pedotransfer functions, or PTFs. PTFs are the critically important components of soil modeling. The purpose of this work was to provide the first comprehensive review of the PTF status and directions of development across Earth science disciplines. The essential challenges appear to be development of PTF for large scale models addressing global and regional problems, PTF of biogeochemical processes in soils and incorporating land use in PTFs. This work encompasses current international experience and will be useful to all professionals developing or using Earth science models.

Technical Abstract: Soil through its functions plays a vital role in the Earth’s ecosystems and provides multiple ecosystem services to humanity. Pedotransfer functions (PTFs) are simple to complex knowledge based rules that relate available soil information to soil properties and variables that are desired or needed to parametrize soil functions. PTFs can be simple regression equations or complex algorithms. In this paper, we review the existing PTFs and document the new generation of PTFs developed in the different disciplines of Earth system science. To meet the methodological challenges for a successful application in Earth system modeling, we emphasize that PTF development has to go hand in hand with suitable extrapolation and upscaling techniques such that the PTFs correctly represent the spatial heterogeneity of soils. PTFsshould encompass the variability of the estimated soil property or process, in such a way that the estimation of parameters allows for validation and can also confidently provide for extrapolation/upscaling purposes capturing the spatial variation in soils. Most actively pursued recent developments are related to soil process parameterizations of heat exchange, solute transport, soil respiration and organic carbon content, root density and vegetation water uptake. Further challenges are to be addressed in parameterization of soil erosivity and land use change impacts at multiple scales.