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Predicting Grain Sorghum Canopy Structure for Soil Erosion Modeling

Armbrust, D. V., Bilbro, J. D.
Agronomy journal 1993 v.85 no.3 pp. 664-668
Sorghum bicolor, canopy, plant morphology, prediction, mathematical models, equations, wind erosion, water erosion
Development of modern water and wind erosion prediction technology requires information on the canopy structure of various plant species to accurately predict the canopy effect on the falling raindrop or the erosive force of the wind. The objective of this study was to develop equations to predict grain sorghum [Sorghum bicolor (L.) Moench] canopy structure characteristics. Groin sorghum plants were sampled weekly from emergence to maturity at Big Spring, TX (1986–1987), and Manhattan, KS (1987), to measure the following crop canopy parameters: plant height, stem length, leaf area, stem area, and canopy cover. Manhattan data were used to develop equations that relate canopy structure parometers of grain sorghum to the total abovegroundry weight, and Big Spring data were used to w~lidate those equations. Leaf and stem area distributions with height also were determined. Coefficients of determination of predicted values using the Manhattan equations and Big Spring above-ground dry weight and the measured Big Spring data ranged from 0.987 for leaf area to 0.922 for stem length. Distribution of leaf and stem area with height remained essentially constant with plant age through the first 7 wk after planting. The equations can be used to supply canopy structure information needed by wind and water erosion prediction models currently under development. Contribution from the U.S. Department of Agriculture, Agricultural Research Se~reice in cooperation with Kansas Agric. Exp. Stn., Contribution number 89-502-J.