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This article in AJ

  1. Vol. 88 No. 5, p. 690-694
    Received: Nov 14, 1994

    * Corresponding author(s): j.passioura@pi.csiro.au
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Simulation Models: Science, Snake Oil, Education, or Engineering?

  1. John B. Passioura 
  1. CSIRO, Div. of Plant Industry, GPO Box 1600, Canberra 2601, ACT, Australia



Crop simulation models can be divided into two groups: those that aspire to improve our understanding of the physiology and environmental interactions of crops (science), and those that aspire to provide sound management advice to farmers or sound predictions to policy makers (engineering). These quite different aspirations require quite different models. Scientific models are mechanistic. With a few exceptions, they have failed to meet their aspirations. They are typically flawed by being based on untestable guesses about the processes that control growth. They may, however, provide useful serf-education for their developers. The best engineering models are based on robust empirical relations between plant behavior and the main environmental variables. Because of their empirical nature, we should not expect them to apply outside the range of the environmental variables used in their calibration. Within their calibrated ranges, however, some have proved useful in providing sound management advice. It is hard to see a useful role, other than serf-education, for models that fall between the scientific and the en~neering types.

Presented at a symposium, Use and Abuse of Crop Simulation Models (jointly sponsored by Div. A-3, the Computer Software Applications Committee, Div. C-2, and Div. S-l), at the ASA-CSSA-SSSA annual meetings in Seattle, WA, 14 Nov. 1994.

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