The model versions released with DSSAT3 do not contain subroutines for simulating the mineralization of animal manures. The N sources that are simulated include soil organic matter, certain N fertilizer sources, and plant residues (e.g. crop residues, plant roots, and green manures). Please refer to Godwin and Jones (1991; in Modeling Plant and Soil Systems, J.Hanks and J.T. Ritchie, eds), Bowen et al. (1993; Agron. J. 85:153), and Quemada and Cabrera (1995; Soil Sci. Soc. Am. J. 59:1059) for more details on model assumptions regarding the N balance. Although the FILEX may contain codes for other N sources, e.g. animal manure, those codes are not presently implemented. The FILEX structure was set up to accomodate future improvements and enhancements in the models, but please note that not all of those options presently work. When in doubt, and one does not have access to the code, run the model with the different options to see if it makes a difference. For example, if you were to set up a FILEX with a green manure source of N compared to an animal manure source with the same dry matter and N content, you will notice no difference; of course the availability of N in green manures versus animal manure is not the same. Some work has been published on the possible structure of subroutines to describe N made available from animal manures--Hoffman, F. and J.T. Ritchie, 1993, J. Agron. & Crop Sciences 170:330. Please feel free to contact me if you have any other questions. ============================== Walter T. Bowen CIP/IFDC Apartado 1558 La Molina, Lima 12 PERU Tel: +51-1-436-6920 FAX: +51-1-435-1570 E-mail: [log in to unmask] USA satellite connection: Tel: (415)833-6635 FAX: (415)833-6636 ============================== ---------- From: Octavio A Castelan-Ortega To: Multiple recipients of list DSSAT Subject: CERES NITROGEN VERSION Date: Wednesday, June 25, 1997 10:23AM Could anyone tell me what is the minimu set of data to calibrate the N version of the ceres-maize model. I also would like to know if the DSSATv3 of ceres accepts manure as a source of fertilizer? Thank you very much Octavio A. Castelan-Ortega Institute of Ecology and Resource Management Scottish Agricultural College West Mains Road Edinburgh EH9 3JG Scotland U.K. e-mail: [log in to unmask] Telephone: (0131)5354080