Effects of Combine Operating Parameters on Harvest Loss and Quality in Rice

Abstract

Combine tests were conducted in commercial rice fields near Keiser, Arkansas. Data was collected and analyzed for two long-grain rice varieties, Newbonnet and Lemont, over a period of two harvest seasons. The test system used allowed for the collection of the clean grain auger discharge, shoe discharge, and rotor discharge separately and simultaneously. Independent variables tested were field speed (feedrate), material-other-than-grain to grain (MOG/G) ratio, moisture content, rotor speed, and concave clearance. Feedrate was the most important factor affecting combine harvest loss. Material-other-than-grain to grain ratio was the second most important factor affecting loss rates. Moisture content, by itself, was significant only in the Newbonnet variety but affected loss rate in the Lemont variety by influencing feedrate and MOG/G ratio. Rotor speed also influenced loss rates but affected each of the varieties differently. Concave setting was significant in both varieties but to a lesser degree in Newbonnet. Head rice yields from combine-harvested samples and hand-harvested samples followed similar trends. Less than two percentage points of reduction in head rice yield were found in the combine-harvested samples when compared to hand-harvested samples.