1. General Model Information

Name: OS&EPIC - erosion - productivity calculator

Acronym: OS_EPIC

Main medium: terrestrial
Main subject: biogeochemistry, hydrology
Organization level: Ecosystems
Type of model: compartment model
Main application:
Keywords: crop growth, groundwater contamination, nitrogen, drainage, fertilizer, water balance, phosphor balance, economic yield, evaporation, erosion, nitrate-drainage,


Guenter Braun
University of Osnabrueck
Institute of Environmental Systems Research
Phone: +49-541-9692546
Fax : +49-541-9692599
email: gbraun@ramses.usf.uni-osnabrueck.de

Fabrewitz, Stefan
Artilleriestr 34
49069 Osnabrueck, Germany
Phone: +49-541-969-0
FAX: +49-541-969-2599


Stefan Fabrewitz


contents of the model
The model describes economic yield, amount of drainage water and resolution of nitrogen in dependence on the type of crop, the type of soil, the amount of water and the use of fertilization either in form of fertilizer or liquid manure. The model assumes a homogeneous area of 1 ha. The soil is vertically divided in up to 10 layers. The model handles the following fields: - water-, nitrogen- and phosphorbalance in the soils and the crops, - cropgrowth, - weather, - soil-temperature. The model is the agrar-ecological part of a multi-disciplinary model describing the drainage of nitrate in the district of Vechta in Lower Saxony. The complete model describes these problems from an ecological, economical and sociological point of view.
principles of the model
The weather is the active part of the model, which is independent from all the other processes. It is determined by the day-values of precipitation, min. and max. air-temperature, global radiation, wind direction and force and atmospheric humidity. Besides that the most important dynamic processes are the ones concerning the water balance, transpiration, evaporation and drainage. They are the main processes for the transport of water and nutrients. Therefore the order of processes is drainage, evaporation, the nitrogen- and phosphorbalance, cropgrowth and fertilization. These processes are described by flows between the pools from a macroscopic point of view.

Author of the abstract: UFIS - Environmental research information system

II. Technical Information

II.1 Executables:

Operating System(s): UNIX Type of computer: Sun sparc Portability onto other systems: Portable to any computer system that is able to run FORTRAN 77. List of files: ANLEGEN.FOR, SIMU.FOR, SETSIMU.FOR, EPINT.FOR, Source files to generate data-sets, simulation, helpprograms, subprograms EPIC. All files are available by anonymous-ftp. internet adress: subdirectory: pub/loc/ASF

II.2 Source-code:

Programming Language(s): FORTRAN 77

II.3 Manuals:

Complete model documentation: Williams, J.R.; Dyke, P.T. et al.: EPIC: The erosion productivity calculator, USDA, agricultural research service (1988).

II.4 Data:

III. Mathematical Information

III.1 Mathematics

III.2 Quantities

III.2.1 Input

III.2.2 Output

IV. References

Williams, J.R., Dyke, P.T. et al., 1988.
EPIC: The erosion productivity calculator.USDA, agricultural research service.

V. Further information in the World-Wide-Web

VI. Additional remarks

OS\&EPIC also offers the option of tillaging the field. If this option is set in the input-files for certain days, the soil water content (\theta^i_j) will then be set to field capacity (FC_j) up to the rooth depth(Z_M), which is calculated in dependence on the total root weight(RWT_i), the root weight in the layers(RTW_{i,j}) and crop specific parameters.

Additional information
Last review of this document by: T. Gabele: 15.July 1997 -
Status of the document:
last modified by Tobias Gabele Wed Aug 21 21:44:47 CEST 2002

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