POROSITY IN LARGE ROUND BALES OF ALFALFA HERBAGE

Bulk porosity was predicted for various radial positions from the bale longitudinal axis of high moisture, soft-center large round bales of alfalfa herbage. Porosity was calculated from viscous coefficients of models developed based upon the knowledge of bale characteristic particle diameter and length as well as pressure drop, air density and viscosity. The pre-baling moisture contents of the bales ranged between 46% and 60% (wet basis) with corresponding bulk mass of 400 to 500 kg. The large round bales were denser in the axial centers (middle of longitudinal axis) compared to the end portions. Predicted porosity ranged from 0.45 in the axial centers to 0.75 at the ends. This variation may be attributed to inadequate weaving across windrow.