|
Submitted to: Journal of Soil and Water Conservation
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 10/5/1996 Publication Date: N/A Citation: N/A Interpretive Summary: Wind erosion (blowing dust) is a natural phenomenon that adversely affects people, plants, equipment, and the environment in general. Windbarriers of trees, shrubs, annual plants, perennial grasses, or man-made materials such slat fences can control wind erosion by reducing wind speeds. Windbarriers reduce the probability of wind erosion by reducing the wind speed at the ground to a speed that is to slow too slow to move the soil particles or l them into the air. A windbarrier should be made up of approximately 50 percent "solid" material (such as plant stems), and the remainder of the windbarrier should be just space. We measured the wind speed reduction 33 feet downwind (at eight inches above the ground) of several windbarriers to determine their relative effectiveness which is expressed as "percent of upwind velocity". The lower this percent is, the more effective is the windbarrier. The king of wind barrier, the number of rows in it, and the percent-of-upwind-velocity values were: switchgrass (one row, 39%), slat-fence (two rows, 43%), slat-fence (one row, 52%), grain sorghum (three rows, 60%), kenaf (eight rows, 69%), forage sorghum (four rows, 76%), kenaf (six rows, 78%), and kenaf (four rows, 79%). This information will be used by scientists in designing windbarriers, and in making computer programs (models which will predict the effectiveness of various types of windbarriers for controlling wind erosion. Technical Abstract: Windbarriers used to control wind erosion may be woody or herbaceous, annual or perennial; or they can be "artificial". To properly space windbarriers, the velocity-reduction characteristics of the windbarrier must be known. Velocity reduction curves for windbarriers of grain and forage sorghum [Sorghum bicolor (L.) Moench], kenaf (Hibiscus cannabinus L.), switchgrass (Panicum virgatum L.), and slat-fences were developed from field measurements. The number of rows in the repective windbarriers and their percent of upwind velocity (the lower the percent the better) at 10 m (32.8 ft) downwind [at 20 cm (8 in) height] were: switchgrass (one row, 39%), slat-fence (two rows, 43%), slat-fence (one row, 52%), grain sorghum (three rows, 76%), kenaf (six rows, 78%), and kenaf (four rows, 79%). These data should be useful in designing windbarrier systems or modeling their effects on downwind velocities. |
