The effect of crop properties on combine performance.

ABSTRACT Combine performance varies due to changing crop conditions which makes it difficult to compare performance data. Often laboratory tests conducted with stored crops fail to predict combine performance in the field. Therefore, it is necessary to characterize a crop by its properties and understand their effect on combine performance. In this study mechanical properties of wheat and barley grain, chaff, and straw were measured and correlated with combine separator and cleaner performance. Crop property and machine performance data were collected in the laboratory and in fields located in five different states. The data were collected over a period of five years. It was found that the cleaner performance was most affected by grain angle of repose, chaff friction, grain density, and chaff mean length. The separator performance was most affected by grain angle of repose, straw density, and grain density. It was also found that the cleaner performance was more sensitive to crop property changes than that of the separator. Effect of moisture content on crop properties and machine performance was also investigated. Regression models were developed to predict the cleaner and separator performance as functions of crop properties.