|Holmes, Brian - UNIVERSITY OF WISCONSIN|
Submitted to: International Silage Conference
Publication Type: Abstract Only
Publication Acceptance Date: July 7, 1999
Publication Date: N/A
Technical Abstract: Bunker silos are one of the principal means of making silage in the US. Their successful use depends on good management including sufficient packing the crop into the silo. While general guidelines for obtaining a good density exist, little is really known about what factors are most important and how these factors interact. In this study, core samples to measure density were taken from over 160 bunker silos on commercial farms. In addition, farmers were surveyed relative to their packing practices. Information requested from farmers included: number of packing tractors, tractor weight, number of tires per tractor, tire pressure, tire condition, number of drive wheels, silage delivery rate, packing time per day, harvest time per day, filling time, filling technique, initial layer thickness, silo dimensions, maximum silage height, crop, crop maturity, and theoretical length of cut. These factors were then correlated with measured ddry matter densities. Dry matter density was positively correlated with average packing tractor weight (W; kg), packing time (T; number of tractors x min/t as fed), and dry matter content (D; g/kg). Density was inversely correlated with the initial depth of the crop when spread in the silo (L; cm). These factors combined together (W*sqrt(T*D)/L) explained 18% of the variation. Use of rear duals or all duals on packing tractors had little effect on density. Other factors such as tire pressure, crop and average particle size were not significantly correlated with density. Thus the low r^2 of the four-parameter packing factor probably reflects variability in accurately estimating parameters such as initial depth of the crop and packing time rather than missing factors important to determining density.