COMPARISON OF 3 METHODS OF RESIDUE COVER MEASUREMENTS ON RAINFALL SIMULATOR SITES

Video image analysis, drop pins, and dot-screen methods were used to m easure wheat residue cover in 1-m(2) rainfall simulator boxes under un disturbed field conditions. The data set consisted of 53 sites on a se t of field plots which represented residue cover on chisel-till and no -till systems two months after wheat harvest. If the mean from the thr ee methods is taken as the true cover, then there was a trend to produ ce 5% cover above average cover values with the pin method and 1% cove r and 4% cover below average values with the dot and video methods, re spectively. For no-till conditions of cover in the 80 to 100% cover ra nge, the differences in values achieved with the three methods may be of little consequence, because the soil is adequately protected. For t he low-residue cover chisel-till conditions, the differences were as m uch as 50% of the mean cover and could produce misleading information on the effect of residue cover on runoff, erosion, water quality, and other products of rainfall simulator studies.