Silage Density Benchmarking

Silage density has been demonstrated to directly correlate with storage dry matter (DM) loss. For each pound of DM/ft3 increase, the dry matter loss may be reduced by 1% (Ruppel, 1995). The density and moisture content of silage determine its porosity. A low porosity suggests less open space or air inside the silage mass. As silages become drier, the density must be increased to maintain the desired porosity. Lower porosity and higher density implies a shorter preliminary aerobic phase of the ensiling process. Fermentation can initiate sooner, thus conserving digestible energy and reducing shrink. Increasing silage density has the additional benefit of reducing silage oxygen exposure on the feedout face and reducing storage space requirements.

Measuring on-farm densities allows one to establish farm-specific goals and monitor progress towards them. Comparing against other farms creates awareness of densities already being achieved elsewhere. High, yet realistic, density goals can then be set.

On-farm density measurements need to be completed safely and strategically. The distance a particular measurement is taken from the top surface of the silage mass has a significant and predictable influence on the density. Only compare densities taken at comparable distances from top surface. The relationship between sample location and density can be leveraged to predict densities in locations that may be deemed unsafe to approach and sample.

Even the highest of densities measured are accomplished by consistently applying the most fundamental principles of silo filling and packing. Although utilization of specialized equipment may provide some advantage, the concepts listed remain foundational:

• WEIGHT vs. RATE: Maintain a minimum of 800 to 1,000 pounds of packing equipment per ton of forage/feed harvested per hour. This may require increasing the weight of existing packing equipment, adding packing machines, and/or slowing the rate of delivery to storage.
• FILL LAYER: Fill in thin layers. Do not exceed six to eight inches of new forage/feed material being added to the pile at a time. Advanced push blade operator skills and/or additional pieces of pushing equipment may be necessary to achieve this.
• CONTINUOUS OPERATION: Packing equipment should operate continuously. Do not stop to wait for the next load to arrive at the silo. Maintain intensive packing efforts from start to finish of storage fill. Practices on the top of a pile have little or no influence on the density at the bottom of the pile.
• SLOPE: Maintain slopes of less than 18º (1:3) in all directions. This may require a larger storage footprint.
• HARVEST DRY MATTER: Stay within the harvest dry matter content target range for the respective crop. When forages begin to get too dry, consider shortening the length of cut.