Density profile of corn silage in bunker silos.

摘要

Six commercial bunker silos were monitored at filling and packing during corn silage harvest. The silos were core sampled at two dates in the following months according to a pattern of 24 holes at six lateral positions and four heights and at two depths in each hole. The dry matter density of individual corn silage samples ranged from 115 to 361 kg DM/m3 (average 234 kg DM/m3). Samples taken in-depth (180 to 360 mm from the vertical face) were always denser than samples taken at the surface (0 to 180 mm from face) by an average of 9%. Samples taken near the top of the silo were always less dense than samples taken near the floor by an average of 23%. Samples taken at the centre were generally denser (11 cases out of 12) than samples taken near the wall by an average of 7%. The pattern of 24 holes cored at two depths illustrated variation according to sampling position and provided a good average density of a bunker cross-section. The in-depth density was considered more representative of stored density than the surface density which was reduced by feed removal operations. The average in-depth density at the six sites was highly correlated with grain percentage and silage height (R2=0.945). A linear regression model predicted very well the experimental average in-depth densities which ranged from 196 to 293 kg DM/m3 while grain percentage ranged from 17 to 50% and silage height from 2.4 to 3.3 m. In the present study, the percentage of grain at harvest was the single most important factor to increase average dry matter density in bunker silos..