A short-term fix nearly 20 years ago has become a standard practice at Adirondack Farms near Peru, N.Y.
"Early in my career and farming on my own, I milked about 150 cows and still was using upright silos," recalled New York dairyman Jon Rulfs. "One year we had a huge corn-silage crop that exceeded our upright silo capacity. We piled the excess on a concrete slab, packed it and sealed it. It worked out great, and I"ve been making silage that way ever since."
Rulfs is now co-owner of Adirondack Farms, a 2,500-cow dairy in upstate New York that was formed in 1996 with his business partner, Jake Swyers. All haylage and corn silage at the dairy is ensiled in drive-over piles. Rulfs said their affordability, flexibility and ease of feedout has made them the silage-storage method of choice for the farm. "Back when I started using piles, there was no research on them," he noted. "The practice definitely has proven itself over time for us."
An attractive option
New York-based agronomy consultant Ev Thomas, Oak Point Agronomics, Ltd., remembers the novelty of Rulfs" silage piles in those early years. Today, he sees more dairies using them versus bunkers or bags.
"Early on, many people thought there was more shrink and spoilage in piles, and if they weren"t managed well, that was true," said Thomas. "But we"ve learned better techniques to pack and seal them, and as dairies grow, they are the least capital-intense method of making more silage."
Drive-over piles require construction of only a smooth, impermeable platform surface, versus additional concrete sidewalls required by bunkers. Packing and feed-out are similar to bunker management, and lack of confined space means pile size can be adjusted based on size of the crop.
Thomas pointed out that silage can be shaved horizontally from small drive-over piles, versus from the front as with bunkers and bags. This keeps the feeding face more uniform, with less surface heating and reduced aerobic spoilage losses. But with higher drive-over piles, it"s much safer to feed from the front.
Also compared to bunkers, they provide flexible storage options for a variety of ensiled crops without the need to build segregated storage space. For example, Adirondack Farms builds separate piles on their 10-acre pad for each of the three to four crops of haylage they put up each year, plus individual piles for conventional and BMR corn silage. Rulfs said they have the additional option to experiment with other crops, such as triticale or sorghum, without having to build segregated storage space.
And while bags provide for that same type of division, they are costlier, require more storage area, are more tedious to feed out, and leave a lot of used plastic to deal with. Plus, piles do not disrupt the rhythm of harvest when a crop is at ideal maturity, which can happen while waiting for custom baggers to arrive.
Pile construction pointers
Proper construction of a drive-over pile can be visualized by imagining a three-dimensional, bell-shaped curve. There are no walls, and the pile slopes gradually from ground-level short-term fix nearly 20 years ago has become a standard practice at Adirondack Farms near Peru, N.Y.
Thomas emphasized the importance of correct packing and shaping. "A common error is to pack front-to-back only, which can result in steep side slopes," he said. "Piles need to be packed front-to-back and side-to-side, at a slope no greater than 1:3 (1 foot of height for every 3 feet of length).
Too-steep slopes result in higher spoilage loss, because not enough weight is allowed to bear down on the forage for adequate packing. If you get to the point that it"s a drive-on pile but not a drive-over pile, it"s too steep. Packing tractors must be able to drive up and over, or you"ll end up with a foot or two of visibly spoiled silage around the outside edge that did not get packed adequately.
Thomas also advises a maximum 30% slope for another reason: safety. He said steeper sides create unnecessary risk of packing tractors tipping over. And even if the surface area is large enough to create a very tall pile, he cautioned the height never should be greater than the vertical reach of the feed-out tractor"s loader bucket. Heights great than that could result in undercut shelves that can collapse and cause serious injury or death.
A minimum dry matter density of 15 lbs./cu. ft. is desirable. A spreadsheet developed at the University of Wisconsin can help determine correct pile size and calculate density, using factors that include harvest delivery rate, feed-out rate, moisture levels and packing tractor weights. The spreadsheets can be accessed at www.uwex.edu/ces/crops/uwforage (search for "Silage Pile Sizing Calculator" and "Silage Pile Density Calculator").
Rulfs also uses a formula to determine correct tractor packing weight: 800 X tons per hour delivered. In addition to adding extra weight to tractors as necessary, Adirondack Farms rents a vibratory sheepsfoot roller – a tool typically used in road and industrial construction – to drive-over piles and create additional settling and compaction.
Details make a difference
Rulfs and his team inoculate every silage crop with sodium diacetate at the chopper to promote good fermentation. When a pile is complete, they double-seal it with a layer of oxygen-impermeable barrier film, followed by a layer of black and white plastic, black side down. They overlap the cover generously at seams and then weight it down with tires that touch continuously over all of the surface area.
Thomas said those are excellent practices and are important to creating and preserving a well-fermented crop. He offers additional drive-over pile tips including:
- Maneuvering space – Allow enough space around and between piles so equipment can easily access the area, during both building and facing phases.
- Drainage – Be sure the site is sufficiently elevated so that rain and melted snow drain away from piles, rather than pooling toward them. Also make sure the route to and from the pile has a well-drained, compact surface that will continue to allow equipment access in muddy or icy conditions.
- Snow accumulation – Do not situate a pile where snow drifts will build against it or block access to it. Install snow fences if necessary.
- Location relative to water sources – Allow at least 300 feet between silage piles and any direct path to groundwater, including surface water, wells, and sink holes.
Adirondack Farms worked with the Natural Resources Conservation Service (NRCS) during construction of their silage storage pad. All precipitation run-off and leachate from the site is channeled through a NRCS-approved bunk leachate system to prevent groundwater contamination. NRCS provided some grant funding for the project.
If you are constructing a new drive-over pile site, government funding may be available to offset some of the cost. Check with your federal Farm Service Agency or NRCS office, and state and local environmental officials, to investigate any programs that may be in place in your region. on the outside to the highest point, or apex, in the center.
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