conversion {soilassessment}

A function for developing own harmonization model

Description

This function enables development of own function for harmonizing soil indicators to standard values

Usage

conversion(x, A, B, method)

Arguments

x

input predictor value

A

location parameter representing the value of target variable when the predictors are minimal (or the y-intercept)

B

Rate parameter representing the rate of change of the target variable with the predictor (or the slope)

method

model relationship between target and predictor variables

Details

model for the relationship between target and predictor variables can be "linear", "power", "exponential", "log". Default is "linear"

Value

model object containing predictive parameters of the conversion model

Author(s)

Christian Thine Omuto

References

van Looy k, Bouma J, Herbst M, Koestel J, Minasny B, Mishra U, Montzka C, Nemes A, Pachepsky AY, Padarian J, Schaap MG, Tóth B, Verhoef A, Jan Vanderborght, van der Ploeg MJ, Weihermüller L, Zacharias S, Zhang Y, Vereecken H. 2017. Pedotransfer functions in Earth System Science: Challenges and Perspectives. Reviews of Geophysics 55(4): 1199-1256.

Sudduth KA, Kitchen RN, Wiebold WJ, Batchelor W. 2005. Relating apparent electrical conductivity to soil properties across the North-Central USA. Computers and Electronics in Agriculture, 46(1-3):263-283

See Also

ECconversion1, ECconversion2, ECconversion4

Examples

x=as.vector(c(0.800,2.580,0.980,0.532,1.870, 18.500,0.430,0.302,0.345,2.700))
y=as.vector(c(17.88,  6.43,  3.83,  7.18,  6.64, 14.83,  4.19,  7.31,  3.21, 18.41))
xy=as.data.frame(cbind(x,y))
names(xy)=c("ECa", "EC")
EC3.ml=nls(EC~conversion(ECa,A,B), start=c(A=0.1, B=0.8), data=xy)
cor.test(fitted(EC3.ml),xy$EC)
plot(fitted(EC3.ml)~xy$EC)
abline(0,1)