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Agronomy Journal Abstract -

Light Penetration in a Row-Crop with Random Plant Spacing1


This article in AJ

  1. Vol. 72 No. 1, p. 131-142
    Received: Nov 9, 1978

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  1. Jerry E. Mann2,
  2. Guy L. Curry,
  3. D. W. DeMichele and
  4. Donald N. Baker



The quantity of solar radiation penetrating a crop canopy and reaching the soil surface affects greatly the microenvironment beneath the canopy. The influence of this microenvironment upon soil radiation and evaporation as well as upon development and mortality rates of insect plant pests is well known. The development of adequate models of light penetration is an important problem associated with the characterization of the subcanopy microenvironment.

In this paper, an analytical model is proposed which estimates the sunlit soil area within a row crop where plants are randomly spaced along rows. Only direct beam, parallel light is considered. The model combines both individual plant geometry and row structure. for simplicity, plant canopies are assumed to be ellipsoidal in shape. The model incorporates plant sizes, row spacings and azimuthal orientation, foliage density, planting density, leaf orientation, and solar location. Available experimental data are inadequate for a complete validation of the model; however, a relative verification was made by comparing model output to real experimental measurements. Included in the paper is a critique of available data in light of the data requirements necessary for satisfactory model validation.

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