FAO56 (version 1.0)

ET_c: Crop Evapotranspiration (ET_c)

Description

ET_c returns the value of crop evapotranspiration.

Usage

ET_c(Kc, ETo)

Value

The function returns the value of crop evapotranspiration as a numeric scalar.

Arguments

Kc

A numeric scalar that denotes the crop coefficient (Kc).

ETo

A numeric scalar that denotes the evapotranspiration rate from the reference surface [mm].

Reference

Allen, R. G., Pereira, L. S., Raes, D., & Smith, M. (1998). Crop evapotranspiration - Guidelines for computing crop water requirements - FAO Irrigation and drainage paper 56. Fao, Rome, 300(9), D05109.

Details

This is a function to calculate the crop evapotranspiration.

See Also

ETo_FPM, ETo_Hrg, ETo_Pan.

Examples

# First example
ET_c(Kc = 0.6, ETo = 0.9)
# Second example
# Computing ET_c of the crop millet planted in Sahiwal, Pakistan
# for a specific day in the initial growth stage
## Loading the relevant Kc dataset
data(Kc_Cereals)
## Latitude in decimal degree
latdeg = 31.685
## Date (2020 June 7)
pdate = "2020-06-07"
## Maximum and minimum temperatures in celsius
temp_max = 38
temp_min = 28
## Actual duration of sunshine and maximum possible duration of sunshine or daylight in hours
actsunshine = 13
maxdaylight = 14
## Elevation above sea level in meter
h = 170
## Wind speed in the height 2m above the ground surface in m/s
ws = 2
##  Evapotranspiration rate from the reference surface (ETo) in mm/day
ET_ref = ETo_FPM(u_2 = ws, e_a = 2.85, T_min = temp_min, T_max = temp_max,
                       phi_deg = latdeg, elev = h, date = pdate, n = actsunshine, N = maxdaylight)
## Crop ET     
CrET = ET_c(Kc = Kc_Cereals$Kc_ini[12], ETo = ET_ref)