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]