A function for harmonizing soil electrical conductivity to the equivalent conductivity of saturated paste extract using mixed effects approach
ME_ECharm(EC, TEXCLASS, model, soilsolution)numeric value of equivalent EC of saturated soil paste extract
a vector or single value of soil electrical conductivity to be harmonized. It should have been determined in a given soil solution (e.g. 1:2, 1:2.5 or 1:5)
soil textural class of the soil whose electrical conductivity is to be harmonized. String or test entry of USDA textural classes: Cl, ClLo,Lo,LoSa,Sa,SaCl,SaClLo,SaLo,SiCl,SiClLo,SiLo,Si,CS,MS,HCL,FS. The classes can be determined from Clay, Silt, and Sand proportions using createTexturedata function
functional model for relating EC to be harmonized and equivalent EC of saturated paste extract. Models considered are second order polynomial, sigmoid, spherical, gaussian, exponential, power, and linear functions. The default is polynomial
– soil:water mix ratio in which electrical conductivity was measured. The function is currently working on 1:2, 1:2.5, and 1:5. The default is 1:2
Christian Thine Omuto
EC harmonization models, which were developed using global datasets, are designed to standardize soil electrical conductivity for applications in soil salt classification
Omuto, C. T., Vargas, R.-R., EL Mobarak, A., Nuha, M., Viatkin, K., & Yigini, Y. (2020). Mapping of salt-affected soils – Technical manual. FAO. https://doi.org/10.4060/ca9215en
Omuto, C. T., Minasny, B., McBratney, A. B., & Biamah, E. K. (2006). Nonlinear mixed effect modelling for improved estimation of water retention and infiltration parameters. Journal of Hydrology, 330(3–4), 748–758. https://doi.org/10.1016/j.jhydrol.2006.05.006
Pinheiro, J. C., & Bates, D. M. (2000). Mixed-Effects Models in Sand S-PLUS. Springer New York. https://doi.org/10.1007/978-1-4419-0318-1
ME_PHharm, ECconversion1, ECconversion2
ndata=data.frame(EC=c(1,0.34,5.07,12.17, 2.219),TEX=c("Cl","SaCl","LoSa", "SiCl","SaClLo"))
ndata$ESa1=ME_ECharm(ndata$EC,ndata$TEX,"power","1:5")
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