Oklahoma State University



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Developers: D. L. Nofziger, Department of Agronomy, Oklahoma State Agricultural Experiment Station, Oklahoma State University, Stillwater, OK 74074 and A. G. Hornsby, Dept. of Soil & Water Science, University of Florida, Gainesville, FL 52611.

Description: CMLS was written to serve as a management tool and a decision aid in the application of organic chemicals to soils. The model estimates the location of the center of mass of non-polar organic chemicals as they move through a soil in response to downward movement of water. The model also estimates the relative amount of each chemical still remaining in the soil at any time. The results may be displayed in graphical and tabular forms. The model was developed so it can be easily used and input parameters are easily obtained.

CMLS is an expansion of a simpler model (CMIS) of Nofziger and Hornsby (Nofziger, D.L., and A.G. Hornsby. 1985. Chemical movement in soil: IBM PC user's guide. IFAS, University of Florida. Circular 654.) for organic chemical movement in a uniform (homogeneous) soil. CMLS differs from CMIS in six ways: (1) This model can deal with soils with up to 20 layers or horizons. Thus, soil properties need not be assumed uniform over all depths. (2) This model enables the user to enter partition coefficients for each horizon in the soil. (3) This model enables the user to specify the degradation half-life of the chemical of interest for each horizon in the soil, rather than using one value for all depths. (4) This model enables the user to simulate movement of the chemical for up to 15 years. (5) This software includes graphical displays for the relative amount of the chemical remaining in the soil as a function of time as well as tabular displays of the time required for the selected chemicals to move to user-specified depths in the soil profile. (6) Data management tools are included to enable the user to enter soil and chemical properties for sites of interest.

Details of the computational algorithm and simplifications used in CMLS are given in a published manuscript (Nofziger, D.L., and A.G. Hornsby. 1986. A microcomputer-based management tool for chemical movement in soil. Applied Agricultural Research 1:50-56). They are also included in electronic form in the user's manual provided with the software.

Applications: Examine the position of the center of mass of a pesticide and amount of pesticide in the vadose zone as a function of time for specific soils, application dates, application depths, infiltration and evapotranspiration conditions.

Compare movement of two chemicals for the same soil and environmental conditions.

Demonstrate the impact of specific soil properties, chemical properties, infiltration, and evapotranspiration upon pesticide leaching. The model has proven to be a useful educational tool.

Released: 1986

Support: CMLS94 is the preferred version of this software today. Our support efforts are focused on that model rather than this original version. We will attempt to address your questions and comments by e-mail if you send them to david.nofziger@okstate.edu.

Resource Requirements: CMLS requires an MS-DOS compatible computer with at least 512 K bytes of random access memory, a graphics monitor, and a floppy disk.

Downloading Information: Software, manual, and sample databases for this original version of CMLS are available in electronic form. Click here to download the original version of CMLS. The self-exploding file occupies approximately 223,000 bytes.

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