Hello,
I have a question related to the soil water balance routine in
CERES-Wheat.  I have 3-5 volumetric soil water content measurements for my
study sites spread throughout the growing season.  My estimates for plant
available water limits are derived using the dssat soil utility from data
in the NRCS SSURGO database.  Most of my study sites are comprised of 1
soil map unit as delineated by SSURGO.  Each of these map units are
comprised of two soil series.  I did a weighted average of both series to
derive the inputs necessary to derive PAW limits using the DSSAT utility.

I have been trying to calibrate CERES-Wheat to fit these volumetric soil
water content measurements, along with yield, and limited phenological
observations.  What I am finding is that there appears to be more than one
combination of parameterizations of the PAW limits that result in model
estimates of volumetric soil water content that match observed estimates of
volumetric water content.  What I conclude from this is that observed data
of volumetric soil water content without associated observed data of PAW
are basically useless?  Any insights to this conclusion would be greatly
appreciated.  Thank you for your time and have a nice day.

Derek McNamara