R/fW.RothC.R In SoilR: Models of Soil Organic Matter Decomposition

```#
# vim:set ff=unix expandtab ts=2 sw=2:
fW.RothC<- structure(
function #Effects of moisture on decomposition rates according to the RothC model
###Calculates the effects of moisture (precipitation and pan evaporation) on decomposition rates according to the RothC model.
##references<< Coleman, K., and D. S. Jenkinson (1999), RothC-26.3 A model for the turnover of carbon in soil:
##model description and windows user guide (modified 2008), 47 pp, IACR Rothamsted, Harpenden.
(P,           ##<< A vector with monthly precipitation (mm).
E,           ##<< A vector with same length with open pan evaporation or evapotranspiration (mm).
S.Thick=23,  ##<< Soil thickness in cm. Default for Rothamsted is 23 cm.
pClay=23.4,  ##<< Percent clay.
pE=0.75,     ##<< Evaporation coefficient. If open pan evaporation is used pE=0.75. If Potential evaporation is used, pE=1.0.
bare=FALSE   ##<< Logical. Under bare soil conditions, bare=TRUE. Dafault is set under vegetated soil.
)
{
B=ifelse(bare == FALSE,1,1.8)
Max.TSMD=-(20+1.3*pClay-0.01*(pClay^2))*(S.Thick/23)*(1/B)
M=P-E*pE

Acc.TSMD=NULL
for(i in 2:length(M)){
Acc.TSMD[1]=ifelse(M[1] > 0, 0, M[1])
if(Acc.TSMD[i-1]+M[i] < 0){
Acc.TSMD[i]=Acc.TSMD[i-1]+M[i]
}
else(Acc.TSMD[i]=0)

if(Acc.TSMD[i]<=Max.TSMD) {
Acc.TSMD[i]=Max.TSMD
}
}

b=ifelse(Acc.TSMD > 0.444*Max.TSMD,1,(0.2+0.8*((Max.TSMD-Acc.TSMD)/(Max.TSMD-0.444*Max.TSMD))))
return(data.frame(Acc.TSMD,b))
### A data.frame with accumulated top soil moisture deficit
### (Acc.TSMD) and the rate modifying factor b.
}
,
ex=function(){
P=c(74,59,62,51,52,57,34,55,58,56,75,71) #Monthly Precipitation (mm)
E=c(8,10,27,49,83,99,103,91,69,34,16,8)  #Monthly open pan evaporation (mm)

Rothamsted=fW.RothC(P,E)
data.frame(month.name,P,E,0.75*E,P-0.75*E,Rothamsted)
# This reproduces Table 1 in the RothC documentation (Coleman and Jenkinson 1999)

}
)
```

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SoilR documentation built on May 29, 2017, 10:57 a.m.