In the course of this study, empirical models were developed for the pressure-density relationship in a large cubic baler for baling alfalfa and barley straw. Least squares regression analysis was employed to develop the empirical model and estimate the model coefficients by minimizing the summation of the squared differences between data resulting from the developed empirical model and the corresponding experimental data for a certain distance from the plunger. The effect of the flake size and

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... load setting on the plunger pressure (pressure exerted on the bale via the plunger) as well as bale density were also determined for bailing alfalfa and barley straw. Results showed that the developed empirical model for either one of alfalfa or barley straw was a combination of a quadratic and an exponential equation which exhibited a good correlation with the experimental data (R 2 of 0.89 for alfalfa and R 2 of 0.94 for barley straw). Results also revealed that load setting significantly affected the plunger pressure and as well the bale density so that plunger pressure and bale density increased with increase in load setting (up to 70% for alfalfa and 100% for barley straw) in both of the forage materials. Flake size (position of the pre-compression sensitivity lever) had also a slight effect on the plunger pressure and on the bale density.