Jon,

I was working with emergence date values earlier this year and tried
adjusting the EDATE values, and the model was unresponsive.  I was told this
is a value that works for many crops in DSSAT, but not in other crops
including CERES-Maize.  Can anyone confirm this?

Kendall DeJonge
Graduate Research Assistant
Colorado State University

On Sat, Nov 7, 2009 at 4:12 AM, Lizaso,Jon I <[log in to unmask]> wrote:

> Jordan and others interested,
> Dr Boote is right. There's no default emergence time in CSM-CERES-Maize,
> the maize model in DSSAT. The model calculates emergence time based on
> thermal time, and depth of seed. The formulation requires a base of 45 GDD
> plus 6 GDD per each cm of seed depth. Soil water is considered for
> germination, the previous stage. If soil moisture is adequate for
> germination the model assumes it's OK for emergence.
>
> The emergence date entry in the file X (EDATE) was not used, different from
> other DSSAT models (e.g. SUBSTOR-Potato). However, sometimes researchers
> have accurate field evaluations of emergence date. In this case, it would be
> better the model to give priority to the X file entry. For this reason, in
> the upcoming DSSAT v4.5 both maize models, CERES-Maize and IXIM, will have
> this feature. If you don't know your emergence date, enter -99 in EDATE and
> the model would calculate it for you. But if you have confidence on your
> measurements of emergence date, input that information in EDATE and the
> model will use it instead of the calculated value.
>
> Regards,
> Jon
>
> Jon I. Lizaso
> Dpto. Producción Vegetal. Fitotecnia
> ETS Ingenieros Agrónomos
> Senda del Rey s/n
> 28040 Madrid, SPAIN
> email: [log in to unmask]
> Tel: 34 91 452 4900 ext 1671
> ________________________________________
> From: DSSAT - Crop Models and Applications [[log in to unmask]] On
> Behalf Of Boote,Kenneth J [[log in to unmask]]
> Sent: Friday, November 06, 2009 6:17 PM
> To: [log in to unmask]
> Subject: Re: Emergence date
>
> Jordan,
>
> I don't think there is a "default" emergence time.  You do not need to
> enter an emergence date in your File X.  The model predicts this as a
> function of heat units (also considers soil water).
>
> In fact, I don't think the "emergence date entry" section of File X of
> DSSAT even acts to truly specify emergence.  I don't know why it is there.
>  I never use it and ignore it.
>
> Ken Boote
>
> -----Original Message-----
> From: DSSAT - Crop Models and Applications [mailto:[log in to unmask]]
> On Behalf Of Jordan Shockley
> Sent: Friday, November 06, 2009 3:18 PM
> To: [log in to unmask]
> Subject: Emergence date
>
> Dear All,
>
>    I was wondering what the default emergence date is for corn in DSSAT if
> one is not entered? Is it the actual planting date, 6 days after planting,
> 10 days after plant, etc?
>
> --
> Jordan Shockley
> University of Kentucky
> Department of Agricultural Economics
> 331 C.E. Barnhart Building
> Lexington, KY 40546-0276
> Email: [log in to unmask]
>



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