Dear Dr. Peter Schoop:
I am trying to calibrate CERES-rice for our tropical lowlands rice farms and I think, based on fields experiments that the genetic coefficients are not constant and independent from the specific environment. When you measure in the field the different variables in the model, you will obtain a great variability. The model has also a great queantity of suppositions on the behaviour of many variables, that doesnīt fit with the well measured in the field. So you must adjust the model to your particular production conditions, acting this way we will improve the models by making the necessary changes for our particular conditions and perhaps in the future we will have universal models that fit everywhere.
Why donīt you write your N-prog model in english?
Sincerely yours: Luis E. Alvarez Larrauri
                 Universidad Ezequiel Zamora. UNELLEZ.
                 Guanare. Estado Portuguesa.
                 Venezuela