| AWCPTF {GSIF} | R Documentation |
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).
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)
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 |
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 |
Returns a data frame with the following columns:
AWCh1: available soil water capacity (volumetric fraction) for h1;
AWCh2: available soil water capacity (volumetric fraction) for h2;
AWCh3: available soil water capacity (volumetric fraction) for h3;
WWP: available soil water capacity (volumetric fraction) until wilting point;
tetaS: saturated water content;
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.
Johan Leenaars, Maria Ruiperez Gonzalez and Tomislav Hengl
Hodnett, M. G., & Tomasella, J. (2002). Marked differences between van Genuchten soil water-retention parameters for temperate and tropical soils: a new water-retention pedo-transfer functions developed for tropical soils. Geoderma, 108(3), 155-180.
Wösten, J. H. M., Verzandvoort, S. J. E., Leenaars, J. G. B., Hoogland, T., & Wesseling, J. G. (2013). Soil hydraulic information for river basin studies in semi-arid regions. Geoderma, 195, 79-86.
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)