Optimizing the Effect of Spike Density and Combine Speed for Reducing Wheat Loss Using Response Surface Methodology

Wheat is the most important crop and food in the feed consumption pattern. By reducing wheat loss in the harvesting stage, it is possible to significantly increase the production of this crop. Due to the acceptance of farmers in the use of straw collecting combines, the number of this type of combines is increasing, especially for harvesting wheat. This research was conducted in order to investigate the effect of spike density per unit area (340, 350 and 440) and the combine forward speed (1, 2 and 3 km/h) on the percentage of quality loss of wheat in harvesting with a straw collecting combine in Khorramabad city. In this research, Response Surface Methodology (RSM) was used to model and minimize the wheat quality loss. The results showed that process variable was statistically significant as quadratic regression model for response (p<0.01). The wheat quality loss is strongly influenced by the combine forward speed and the spike density per unit area. The lowest percentage of wheat quality loss (1.9%) was related to the speed of 1 km/h and the spike density of 340 spikes/m2.