MASS REDUCTION OF STANDING AND FLAT CROP RESIDUES BY SELECTED TILLAGEIMPLEMENTS

Field data were collected to determine the mass reduction of standing residue by selected tillage operations and to develop a set of coeffic ients that could represent changes in mass between standing, flat and buried residue pools caused by those tillage operations. Tillage imple ments used in this study were tandem-disk harrows, chisel plows, and w ide-sweep plows. A range of pre-tillage corn and wheat residue conditi ons were studied, with standing and flat residue pools sampled separat ely before and after each tillage operation. The data show that 7% of standing corn residue was flattened with a wide-sweep plow, 89 to 100% with tandem-disk harrows, 29% with a straight-shank chisel plow, and 76% with a twisted-point chisel plow. Wheat residue data, indicated th at 53 to 55% of the standing residue was flattened with the wide-sweep plows, 86% for a wide-sweep plow outfitted with a rolling harrow trea der attachment, and 86 to 95% for the tandem-disk harrows. The two str aight-shanked chisel plows, one outfitted with a drag harrow attachmen t using coil-spring wire teeth and one without an attachment, flattene d 90% and 22% of the standing wheat residue, respectively. A set of tr ansfer equations also was developed to represent changes in mass betwe en standing, flat, and buried residue pools from tillage operations. O nly three coefficients (flattening, burial, and surfacing) are necessa ry to describe the transfer of mass from one residue pool to another. Coefficient values, determined via a constrained optimization procedur e, are presented for each tillage implement on both corn and wheat res idues.