The difficulty of getting a uniform residues distribution, in the width of the combine cutting ban, have been observed in crop fields. The objective of this work was to evaluate the uniformity of straw distribution for combines harvesting soybean. It was appraised nine combines in the operation conditions and adjustment that they were being used by the operator. The Coefficient of Variation (CV) was used for comparison of the machines and the evaluation of the distribution uniformity, and had accomplished a multivariate analysis to evaluate the similarity among the combines in function of the coefficient of variation, humidity of the straw and width of the cut platform. All the combines had presented a disuniform straw distribution, resulting in bands, with raised straw concentration in the combine central part and little in the extremities, independently of the width of the cut platform. But a combine presented distribution next to the ideal, for also possessing a delivering system for the straw proceeding from the bolters. One evidenced that the deriving straw of the combine bolters can be the responsible for the formation of bands with raised amounts of straw in the combine center, independently of the machine size.
agricultural machines; no tillage; plants residue
