Minnesota/Wisconsin Engineering Notes

November 2001 Low Cost Parlors For Wisconsin and Minnesota Dairy Producers Siting Animal Production Operations Sizing Silage Piles New Agricultural and Alternative Energy Web Page Use Winter to Make Your Farm Safer Increasing pH by Low Level Aeration to Remove Soluble Phosphorus in Liquid Swine Manure Farmland Tile Drainage Design Workshop New Agricultural Drainage Publications Available Two New Farm Business Management Publications Available New University of Minnesota Department Head Resources Calendar

Sizing Silage Piles Brian J. Holmes, Wisconsin Extension Engineer Silage piles are a way to store silage with low initial investment. With good management, dry matter losses in storage and feedout can be kept in the range of 15-25%. Practices recommended for bunker silos* apply to silage piles as well. To obtain good forage density and avoid tractor rollovers when packing the pile, the side slopes should not be too steep. A slope of 3 ft horizontal to 1 ft vertical should be satisfactory. A face removal rate of at least 6 in/day will keep feedout losses to a reasonable level. A 12 in/day removal rate is better. Following are the steps required to size a silage pile. Step 1: Determine daily dry matter need. In this example, assume the forage is hay silage and 250 animals will consume 12 lbs dry matter (DM) per animal per day. The daily consumption becomes: 250 animals x 12 lbs DM/animal-day = 3000 lbs DM/day Step 2: Determine volume removed each day. If forage is packed well, the density will be greater than 14 lbs DM/ft³. In our example, let’s assume a density of 14.5 lbs DM/ft³. The volume removed then becomes: 3000 lbs DM/day / 14.5 lbs DM/ft³ = 206.9 ft³/day Step 3: Determine the area of the pile cross-section. Select a face removal rate during feedout. In this example, use a 1-ft removal rate. Then the cross-section becomes: 206.9 ft³/day / 1 ft/day = 206.9 ft² Step 4: Determine the average pile width. Assume a pile depth. In this example, assume the pile will be built to a depth of 6 ft. Next, assume a forage loss rate; in this case, let’s use 20%. The forage loss adjustment factor then becomes 1 + 20/100 = 1.2. The average pile width is then: 206.9 ft² x 1.2/6 ft = 41.4 ft ˜ 41 ft Step 5: Determine pile bottom width. To the average width, add the depth times the sidewall slope. In our example, assume a slope of 3:1. The bottom width becomes: 41 ft + (6 ft x 3) = 59 ft Step 6: Determine pile top width. To the average width, subtract the depth times the sidewall slope. The top width becomes: 41 ft - (6 ft x 3) = 23 ft Step 7: Determine the pile average length. Assume a feeding period during which the pile will be used. In our case, let’s use 200 days. The average length then becomes: 200 days x 1 ft/day = 200 ft Step 8: Determine the pile bottom length. To the average length, add the depth times the end wall slope. In our example, assume a slope of 2:1. The bottom length becomes: 200 ft + (6 ft x 2) = 212 ft The pile bottom dimensions in our example are 59 ft x 212 ft. Step 9: Determine the pile top length. To the average length, subtract the depth times the end wall slope. The top length becomes: 200 ft - (6 ft x 2) = 188 ft Step 10: The quantity of feed placed into the pile is: 3000 lbs DM/day x 1.2 x 200 days/(2000 lbs/T) = 360 T Step 11: The quantity of feed fed from the pile is: 3000 lbs DM/day x 200 days/(2000 lbs/T) = 300 T DM Ken Barnett, the Marathon County (WI) Extension Agent, has developed a spreadsheet to automate the process of sizing a silage pile. This spreadsheet is available on the Team Forage web site: http://www.uwex.edu/ces/crops/uwforage/storage.htm To assure access to a silage pile in all weather, a good base is required. This can be provided by concrete, asphalt, or Macadam/geotextile. Farm and Home Concrete Handbook (MWPS-35) contains design information for concrete slabs, and Using All-Weather Geotextile Lanes and Pads (AED-45) has design information for Macadam/geotextile surfaces. For ordering information on both of these MidWest Plan Service publications, click here. *Managing and Designing Bunker and Trench Silos (AED-43), MidWest Plan Service, Ames, IA.

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