Hi Joy (?),

IMHO model evaluation is always necessary, unless you apply the model within very narrow boundaries. For example, you have wheat cultivar x in location y on one field, and would like to run it on a neighbored field with same soil properties. Then I would assume that now further calibration or evaluation is required.

But I'd say if you change soils from, say, loam to clay, you would need to have some data for calibration and evaluation.

My experience tells me that especially clayey soils are difficult to simulate, as there might be quite some uncertainty e.g. in regard to field capacity, permanent wilting point and infiltration characteristics.
Not sure though how CERES-Rice simulates inundated soils, and water requirements. I would assume that you have to set saturated hydraulic conductivity at the bottom of your profile, and that this most likely drives infiltration and water redistribution, saturation and thus overall water requirements. But, as I said, I am not sure.

Regards,
Rolf


> -----Original Message-----
> From: DSSAT - Crop Models and Applications
> [mailto:[log in to unmask]] On Behalf Of Joy Mondejar
> Sent: Mittwoch, 30. Januar 2013 20:01
> To: [log in to unmask]
> Subject: model evaluation
>
> Dear all:
>
> Is it always necessary to undergo CERES-Rice model evaluation before we can
> proceed to model application and simulate rice yields?
> I mean for each location that we want to predict rice yields, do we  need to
> evaluate the model and get the site soil profile and soil surface data, crop
> management data from a field experiment, and observed experimental data
> from the experiment?
>
> I ask this since I am thinking if I can use a default  clay soil profile available in
> DSSAT to simulate rice yields for 4 different locations.
>
> Thanks for the help and advice.