Dears David, Carina and Robert,

Many thanks for your answers.

As David said, I should state my question more clearly.  I searched the
literature and found only two publications demonstrating or discussing the
economic value of using a crop model at the farm level.  Both talk about the
Gossym-Comax DSS.

I know all the positive arguments developed by David about the interest in
crop models for agriculture, and I share them.  However, few crop model
advocates attempt to demonstrate their points by experimenting with real
situation use of crop models vs. current farmer practices in calculating
monetary gains or losses. Perhaps I didn't search the best biblio-database,
so I am asking members of the DSSAT group to let me know if they are aware
of such publications. I am looking for papers with real data, collected at
the farm level, showing the advantages and/or disadvantages of crop models
and DSS use in the production process.

Excuse me for this insistence, but I believe that there are such papers and
perhaps some of you are aware of them.

Thank you for your help.

Eric