Wind speed above and within sunflower stalks varying in height and population

Low amounts following sunflower harvest in the central Great Plains appear to leave the soil unprotected against wind erosion. No quantitative data ex ist describing the effects of standing sunflower residues on wind speed wit hin the standing stalks. The objectives of this study were to measure the e ffects of stalk height, population, and diameter (quantified as silhouette area index) on: 1) wind speed within sunflower residue, 2) friction velocit y, and 3) erosion ratio of bare surfaces compared with surfaces with standi ng stalks. As the silhouette area index increases in response to increases in stalk height, population, or diameter, wind speeds near the soil surface decrease, friction velocity increases, and erosion potential decreases. Ty pical amounts of standing sunflower stalks cut to a height of 50 to 70 cm ( 20 to 38 in) would reduce erosion to less than 5% of the amount predicted f or a bare soil surface.