CSR Soil Water

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The module SoilWater of CSR serves to determine water stress on plants, caused by the actual moisture content of the soil.

SoilWater relates the soil water ratio θ to the potential force h that has to be excerted by the plant roots to draw the water from the soil. Wösten-Van Genugten pedotransfer-functions (ptf) are used to estimate the pressure heads.


Create an instance of the SoilWater-class. The object has a method called selfTest() which may be used to verify that the model calculations produce the same results as the published data on the pedotransfer-functions. Since the ptf use a large number of regrression parameters, the selfTest is quite important, but it is not necessary always to run it.

After instantiation, the soil type must be defined. Six predefined types are available:

  • Coarse
  • Medium
  • MediumFine
  • Fine
  • VeryFine
  • Organic

Alternatively, user defined soil types may be assigned, supplying OM, texture, and density. In the example below first the predefined type MediumFine is assigned to the object, but in the next code line it is overruled by giving it a user defined type:

sw = SoilWater()
sw.selfTest(verbose = False)
sw.setSoilType(True, SoilClasses.MediumFine)
sw.setSoilType(True, OrganicPct = 7.8, ClayPct = 4.3, SiltPct = 11.7, BulkDensity = 1.25)
print sw

Soil Type: user-defined (OM 7.8%, clay 4.3%, silt 11.7%, density 1.25 [kg/dm3]
  fieldCapacity: 0.228445
  wiltingPoint : 0.096782
  h1           : 0.000000
  h2           : 330.000000
  h3l          : 500.000000
  h3h          : 800.000000
  h4           : 15000.000000
  PTF          : theta_r: 0.025000; theta_s: 0.457259; alpha: 0.045985; Ks: 53.370084; l: -0.929805; n: 1.274669; m: 0.215483


pressurehead functions

reduction function