VSD+

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input structure

TYPE mod var description units
integer modExc cation exchange model option: 1=Gaines-Thomas, 2=Gapon
real dt time stepsize dy
real pCO2 partial CO2-pressure in soil solution atm
real KAlox Al equilibrium constant (eq/m3)^(1-expAl)
real expAl exponent in [Al]=eqK%Alox*[H]^expAl
real thick soil thickness m
real rho bulk density g/cm3
real theta volumetric water content of the soil m3/m3
real thetao volumetric water content of the soil at previous timestep m3/m3
real thetasat volumetric water content of the soil at saturation m3/m3
real thetafc volumetric water content of the soil at field capacity m3/m3
real theta1bar
real thetawp volumetric water content of the soil at wilting point m3/m3
real CEC cation exchange capacity of the soil meq/kg
real KAlBc selectivity constant for Al-Bc exchange
real KHBc selectivity constant for H-Bc exchange
real temp average soil temperature oC
real ps precipitation surplus m
real coacid total concentration of organic acids (m*DOC) mol/m3
real *3 pKpar(3) 1-3 parameters of (Oliver-type) mono-protic organics model: pK = pKpar(1)+pKpar(2)*pH-pKpar(3)*pH^2
real kni maximum nitrification rate at Tref yr-1
real kde maximum denitrification rate at Tref yr-1
real Nfix N fixation rate eq/m2/yr
real Clf C litterfall g C/m2
real ctclay clay content of the soil  %
real Calc Fraction Ca in carbonates

-1 = no carbonates in soil, 0 = pure MgCO3, 1 = pure CaCO3 (e.g. for dolomite Calc = 0.5) || -

type(Ions) Wea weathering rate of X

note:: is zero for NO3, NH4, Cl|| eq/m3/yr

type(Ions) Dep deposition rate of X eq/m2/yr
type(Ions) Lf litterfall of X
note: VSDp will sum litterfall of NO3 and NH4; is zero for SO4, Na, Cl
eq/m2

exchange structure

TYPE mod var description units
integer istart start flag; if true: initialise certain variables for use in simulation; set to false afterwards (see NOTES)
real CNrat C:N ratio in topsoil g/g
real Csoil organic C content of soil g/m2
real cH H+ concentration eq/m3
real ECa exchangeable fraction of Ca
real EMg exchangeable fraction of Mg
real EK exchangeable fraction of K
real *10 CN(10) CN ratio of the C pools -
real *10 Cpool(10) size of C pools g/m2
real Nbal (no doc)
type(Ions) Upt net uptake of X
note:: VSDp will modify distribution of N uptake over NO3 and NH4; is zero for SO4, Na, Cl
eq/m2
type(Ions) Conc concentration of ion X (SO4,NO3,NH4,Ca,Na,Cl) eq/m3