llwrPTF {soilphysics}

Least Limiting Water Range (LLWR) Using Pedo-Transfer Functions

Description

It calculates Least Limiting Water Range (LLWR) using pedo-transfer functions in according to Silva \& Kay (1997) and Silva et al. (2008), for Canadian and Brazilian soils, respectively.

Usage

 
llwrPTF(air, critical.PR, h.FC, h.WP, p.density, Bd, clay.content, org.carbon = NULL)

Arguments

air

the value of the limiting volumetric air content, m^3 m^{-3}

critical.PR

the value of the critical soil penetration resistance, MPa

h.FC

the value of matric suction at the field capacity, hPa

h.WP

the value of matric suction at the wilting point, hPa

p.density

the value of the soil particle density, Mg m^{-3}

Bd

a numeric vector containing values of dry bulk density, Mg m^{-3}. Note that Bd can also be a vector of length 1.

clay.content

a numeric vector containing values of clay content to each bulk density, \%

org.carbon

a numeric vector containing values of organic carbon to each bulk density, \%, for Canadian soils. Default is 2\%. See details.

Details

Note that org.carbon is only required for Canadian soil. If it is not passed, LLWR for Canadian soil is calculated with 2\% of organic carbon.

Value

A list of

LLWR.B

LLWR for Brazilian soils

LLWR.C

LLWR for Canadian soils

Author(s)

Renato Paiva de Lima <[e-mail]>

Anderson Rodrigo da Silva <[e-mail]>

Alvaro Pires da Silva <[e-mail]>

References

Keller, T; Silva, A.P.; Tormena, C.A.; Giarola, N.B.F., Cavalieri, K.M.V., Stettler, M.; Arvidsson, J. 2015. SoilFlex-LLWR: linking a soil compaction model with the least limiting water range concept. Soil Use and Management, 31:321-329.

Silva, A.P.; Kay, B.D. 1997. Estimating the least limiting water range of soil from properties and management. Soil Science Society of America Journal, 61:877-883.

Silva, A.P., Kay, B.D.; Perfect, E. 1994. Characterization of the least limiting water range. Soil Science Society of America Journal, 61:877-883.

Silva, A.P., Tormena, C.A., Jonez, F.; Imhoff, S. 2008. Pedotransfer functions for the soil water retention and soil resistance to penetration curves. Revista Brasileira de Ciencia do Solo, 32:1-10.

Examples

# EXEMPLE 1 (for Brazilian Soils) 
llwrPTF(air=0.1,critical.PR=2, h.FC=100, h.WP=15000,p.density=2.65,
        Bd=c(1.2,1.3,1.4,1.5,1.35),clay.content=c(30,30,35,38,40))

# EXEMPLE 2 (for Canadian Soils)
llwrPTF(air=0.1,critical.PR=2, h.FC=100, h.WP=15000,p.density=2.65,
        Bd=c(1.2,1.3,1.4),clay.content=c(30,30,30), org.carbon=c(1.3,1.5,2))

# EXEMPLE 3 (combining it with soil stress)
stress <- stressTraffic(inflation.pressure=200, 
	        recommended.pressure=200, 
	        tyre.diameter=1.8, 
	        tyre.width=0.4, 
	        wheel.load=4000, 
	        conc.factor=c(4,5,5,5,5,5),
                layers=c(0.05,0.1,0.3,0.5,0.7,1), 
	        plot.contact.area = FALSE)

stress.p <- stress$Stress$sigma_mean
layers <- stress$Stress$Layers
n <- length(layers)
def <- soilDeformation(stress = stress.p,
                p.density = rep(2.67,n),
	          iBD = rep(1.55,n), 
                N = rep(1.9392,n), 
                CI = rep(0.06037,n), 
                k = rep(0.00608,n), 
                k2 = rep(0.01916,n),
                m = rep(1.3,n),graph=TRUE,ylim=c(1.4,1.8))

# Grapth LLWR, considering Brazilian soils
plot(x = 1, y = 1, 
     xlim=c(0,0.2),ylim=c(1,0),xaxt = "n",
     ylab = "Soil Depth",xlab ="", type="l", main="")
axis(3)
mtext("LLWR",side=3,line=2.5)

i.LLWR <- llwrPTF(air=0.1,critical.PR=2, h.FC=100, 
                        h.WP=15000,p.density=2.65,
                        Bd=def$iBD,clay.content=rep(20,n))
f.LLWR <- llwrPTF(air=0.1,critical.PR=2, h.FC=100, 
                        h.WP=15000,p.density=2.65,
                        Bd=def$fBD,clay.content=rep(20,n))

points(x=i.LLWR$LLWR.B, y=layers, type="l"); points(x=i.LLWR$LLWR.B, y=layers,pch=15)
points(x=f.LLWR$LLWR.B, y=layers, type="l", col=2); points(x=f.LLWR$LLWR.B, y=layers,pch=15, col=2)

# End (not run)