The Effect of Moisture and Stage of Maturity on Physical Properties of Switchgrass (Variety: Kanlow)

Abstract

The knowledge of physical properties of cellulosic biomass is important for the design and execution of various operations such as harvesting, baling, and size reduction. This research study measured ultimate tensile and shear strength for the second and the third intenode of the Kanlow variety of switchgrass before and after frost. The experiments were conducted at 11 harvesting intervals or maturity stages before frost (1-4) and after frost (5-11). Shear strength was measured using a double shear box and a standard serrated sickle arrangement. Tensile strength was measured by a special test sample preparation which facilitated controlled failure at the center of the sample. The mean moisture content decreased rapidly after frost. The moisture content before and after frost varied from 50 to 65 % and 9 to 38 % (w.b.), respectively. The ultimate double and sickle shear stress did not show any clear trend with varying maturity stage and moisture content. The ultimate double shear stress values were higher for the maturity stage with maximum moisture content and minimum for the maturity stage with minimum moisture content. The ultimate double and sickle shear stress were higher for the second internode than the third internode. The ultimate tensile stress decreased with the decrease in moisture content. Measurements of the ultimate tensile stress showed that the second and the third internodes were not significantly different. It can be concluded that the choice of time of harvesting is crucial for different agricultural operations