1. General Model Information

Name: Sigma +

Acronym: SIGMA

Main medium: terrestrial
Main subject: biogeochemistry
Organization level: ecosystem
Type of model: partial differential equations (2D), ordinary differential equations
Main application:
Keywords: crop, cotton growth, plant-soil-atmospheric interactions, management


Hal Lemmon
Western Regional Research Center
USDA 800 Buchanan Street
Albany, CA 94710
Phone: 510-559-5965
Fax : 510-559-5798
email: hlemmon@asrr.arsusda.gov


Hal Lemmon and Ning Chuk


Sigma + is a cotton growth model that simulates plant-soil-atmospheric interactions for the purposes of examining potential effects of climate change and providing management information to cotton farmers. The model uses 2DSOIL, a two-dimensional root-soils model developed at the ARS Salinity Laboratory.

This model is part of a larger effort to develop new crop models and to develop graphical user interfaces (GUI) for existing crop growth models (e.g. GLYCIM ) for the purposes of interfacing them with soils models. The models can be used for the purposes of management of agricultural chemicals and examining the possible effects of climate change on plant growth.

Author of the abstract:


II. Technical Information

II.1 Executables:

Operating System(s): Model requires 4 minutes to simulate one season on a SunSparcStation; 30 minutes on a 486, 33 mhz PC

II.2 Source-code:

Programming Language(s): C++ for all but the soils models. FORTRAN for the soils models.

II.3 Manuals:

II.4 Data:

III. Mathematical Information

III.1 Mathematics

III.2 Quantities

III.2.1 Input

Variety data, weather data, soil parameters, irrigationschedule, fertilization schedule. Approximately 150 plots showing the growth of the cotton plants and the

III.2.2 Output

Approximately 150 plots showing the growth of the cotton plants and theevolution of a large number of parameters.

Temporal Scale: From emergence to harvest.

Spatial Scale: A cotton field.

IV. References

V. Further information in the World-Wide-Web

VI. Additional remarks

This model is potentially valuable to the climate change research becauseit interfaces known crop growth models with a soils dynamics model. Inaddition, the model is designed to examine the effects of chemical inputson water pollution.
Last review of this document by: T. Gabele: 08. 07. 1997 -
Status of the document:
last modified by Tobias Gabele Wed Aug 21 21:44:49 CEST 2002

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