ABSTRACT: The photographic, meterstick, and line-transect methods of measuring the percentage of land covered with crop residue were evaluated by comparing residue cover on 10 Iowa fields farmed with conservation tillage. Although the line-transect method overestimated crop residue by 6 to 10 percent, variability in measurements proved less than with the photograph and meterstick methods. The line-transect method is preferable for field use, particularly if technicians are carefully trained in its use and in self-calibration so that overestimation of crop residue can be avoided.