Relating Plant Canopy Characteristics to Soil Transport Capacity by Wind
- Dean V. Armbrust and
- James D. Bilbro
Federal legislation mandates that wind erosion soil losses be kept to a “ tolerable” limit to maintain eligibility for federal farm programs on highly erodible land. Therefore, much interest has been generated in devising wind erosion models that accurately determine the potential erosion from a given site and also evaluate the effectiveness of any control measure. These models require mathematical relationships between surface properties and the transport capacity of the wind. Such relationships are available for soil surface roughness and plant residues, but not for growing crops. Our objective was to establish these relationships for growing crops. We developed a theoretical approach that accounts for the effect of stem area, leaf area, and canopy cover of growing crops on the soil loss ratio, threshold velocity, and transport capacity. The predictive ability of the theory was tested using published data sets from growing plants tested in a wind tunnel. Measured soil loss ratios were highly correlated to predicted values (r2 = 0.99, P = 0.001). The results showed that plant area index and canopy cover are highly correlated with reduction in the transport capacity of the wind and, therefore, serve as indicators of the soil protection afforded by growing plants. A plant area index of 0.02 and a canopy cover of 4% reduced the transport capacity of a 16 m s−1 wind by 50%. This method for determining the protective ability of a combination of growing plants and standing residue will improve predictive capabilities of wind erosion models for more diverse farm management conditions.
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