AWCPTF {GSIF}R Documentation

Available soil water capacity

Description

Derive available soil water capacity (in cubic-meter per cubic-meter) based on a Pedo-Transfer Function developed using the Africa Soil Profile Database (Hodnett and Tomasella, 2002; Wösten et al. 2013).

Usage

AWCPTF(SNDPPT, SLTPPT, CLYPPT, ORCDRC, 
    BLD=1400, CEC, PHIHOX, h1=-10, h2=-20, h3=-31.6, 
    pwp=-1585, PTF.coef, fix.values=TRUE, print.coef=TRUE)

Arguments

SNDPPT

numeric; sand content in percent

SLTPPT

numeric; silt content in percent

CLYPPT

numeric; clay content in percent

ORCDRC

numeric; soil organic carbon concentration in permille or g / kg

BLD

numeric; bulk density in kg / cubic-meter for the horizon/solum

CEC

numeric; Cation Exchange Capacity in cmol per kilogram

PHIHOX

numeric; soil pH in water suspension

h1

numeric; moisture potential in kPa e.g. -10 (pF 2.0)

h2

numeric; moisture potential in kPa e.g. -20 (pF 2.3)

h3

numeric; moisture potential in kPa e.g. -31.6 (pF 2.5)

pwp

numeric; moisture potential at wilting point in kPa e.g. -1585 (pF 4.2)

PTF.coef

data.frame; optional conversion coefficients (Pedo-Transfer Function) with rows "ai1", "sand", "silt", "clay", "oc", "bd", "cec", "ph", "silt^2", "clay^2", "sand*silt", "sand*clay" and colums "lnAlfa", "lnN", "tetaS" and "tetaR" (see Wösten et al. 2013 for more details)

fix.values

logical; specifies whether to correct values of textures and bulk density to avoid creating nonsensical values

print.coef

logical; specifies whether to attach the PTF coefficients to the output object

Value

Returns a data frame with the following columns:

Note

Pedotransfer coefficients (PTF.coef) developed by Hodnett and Tomasella (2002). fix.values will correct sand, silt and clay fractions so they sum up to 100, and will replace bulk density values using global minimum maximum values.

Author(s)

Johan Leenaars, Maria Ruiperez Gonzalez and Tomislav Hengl

References

Examples

SNDPPT = 30 
SLTPPT = 25 
CLYPPT = 48 
ORCDRC = 23 
BLD = 1200 
CEC = 12 
PHIHOX = 6.4
x <- AWCPTF(SNDPPT, SLTPPT, CLYPPT, ORCDRC, BLD, CEC, PHIHOX)
str(x)
attr(x, "coef")

## predict AWC for AfSP DB profile:
data(afsp)
names(afsp$horizons)
## profile of interest:
sel <- afsp$horizons$SOURCEID=="NG 28440_Z5"
hor <- afsp$horizons[sel,]
## replace missing values:
BLDf <- ifelse(is.na(hor$BLD), 
   mean(hor$BLD, na.rm=TRUE), hor$BLD)
hor <- cbind(hor, AWCPTF(hor$SNDPPT, hor$SLTPPT, 
  hor$CLYPPT, hor$ORCDRC, BLD=BLDf*1000, hor$CEC, 
  hor$PHIHOX))
str(hor)

[Package GSIF version 0.5-3 Index]