CropSyst, a management-oriented crop growth model, was modified to assess c
rop response to salinity. The effect of salinity was included in the existi
ng water uptake module by adding an osmotic component to the soil water pot
ential and developing a function to account for salinity effects on root pe
rmeability. The effect of salinity on water uptake is the link to simulate
crop growth reduction. A qualitative analysis showed that the model simulat
ed expected trends of crop response to salinity as affected by cultivar tol
erance, atmospheric vapor pressure deficit, and soil water availability. Co
mparisons with data from sprinkler line experiments were performed for barl
ey grown at Zaragoza (Spain) in 1986 and 1989, nd corn at Davis, Calif. and
Fort Collins, Cole. in 1975. These experiments included different salinity
and irrigation levels. At Davis, the model simulated well the effect of sa
linity/irrigation treatments on water use, biomass, and crop yield, with va
lues for the Willmot index of agreement (d) generally better than 0.94 (a v
alue of 1.0 implying perfect agreement). At Fort Collins, simulation of gra
in yield was less satisfactory (d fluctuated between 0.83 and 0.90), but th
e agreement was good for crop water use and biomass (d generally better tha
n 0.96). The lower performance for grain yield was attributed to large and
erratic variations in the observed harvest index. The agreement between sim
ulated and observed values tended to be lower at Zaragoza, with d values fl
uctuating between 0.84 and 0.91 for biomass and yield in the 2 years includ
ed in this evaluation. Unusually high measured yields in 1989 and erratic v
ariation in 1986 were attributed to small sample size. The small size (incr
eased measurement error) of samples typically obtained in sprinkler line so
urce experiments tends to limit their use for evaluation of simulation mode
ls.