Tweaking composting bedding
April 29, 2008 by Paul MacDonald
With a bit of tweaking, the
composting bedded pack approach to manure management is working out
well for the Portner dairy operation in Minnesota, with the manure-wood
shavings combination proving to be a good nutrient for the farm.
With a bit of tweaking, the composting bedded pack approach to manure management is working out well for the Portner dairy operation in Minnesota, with the manure-wood shavings combination proving to be a good nutrient for the farm.
It may not be suitable for all dairy operations, but the composting bedded pack approach to farm and manure management is being seen on increasingly more dairy farms. The system seems to have really caught on among dairy producers in Minnesota, with a number of dairy farms switching to composting bedding in the last several years.
|Tom Portner with one of the two Gehl skid-steer machines that, among other chores, are used for twice-daily stirring of the composting bedded pack.|
For Minnesota dairy producers—and brothers—Tom and Mark Portner, the system has worked so well in one of their barns that they are also using it in a newly constructed barn. And the manure-wood shavings combination that results is proving to be a good nutrient for their farm and neighboring land.
The Portners, who have been using the system in their first barn for four years, note that they are taking a system that has been developed by other dairy farms and adapting it to their operation. “We’re just utilizing what other people have done, and different parts of it are all coming together to make it work in our part of the country,” says Tom Portner.
In their case, they heard that Virginia dairy producer Calvin Paulson was using composting bedding packs and contacted him for details about what worked and what did not work for him. “We talked to Calvin, and he told us he had tried a bunch of different types of bedding material, but found that sawdust worked best,” explains Tom. “We had concerns about udder health and mastitis, but Calvin said he was running some of the lowest cell counts in his area. We also had concerns about what would happen to the bed pack at 20 or 25 degrees below zero, but because he is in Virginia, he could not help us with that one.”
They ran a bit of a pilot mini-barn operation, setting up a few cows that had been getting banged up in a freestall barn setting, in a small lean-to with bed pack.
“These cows turned around and had very good lactations, and we figured it would be good to get all our cows into something like this.” To hedge their bets, the Portners designed their first barn, which is 136 feet by 54 feet, so they could convert to a freestall barn as a fallback plan. Unlike Paulson, who feeds his cows outside, they built feeding alleys inside, to take into account the cold weather in Minnesota.
|The new barn at the Portner dairy operation, 54 feet by 224 feet, took about 120 cubic yards of sawdust for compost bedding. The actual bedding pack area is about
42 feet by 184 feet.
“We took a lot of the concepts of the free stall barns and utilized them for the design of the building, the design of the feed alley, and things like that,” says Tom.
The Portners were already getting coarse sawdust from a local supplier and arranged to switch to getting fine sawdust instead. It has worked extremely well, they say.
Taking the skid steer, they stir the composted material twice a day. Besides providing a fresh surface for cows to lie on, the stirring mixes the manure and urine on the surface into the bedded pack. Any other manure, such as from the feed alley, and the bedding is eventually scraped together and stored in a small separate area at the end of the barn.
Humidity and flies have a direct impact on how long the composted bedpack lasts. With the warm, humid weather in Minnesota in June and July, the cows have a tendency to group up.
“You can have all the fans in the world, but they still want to stand where they can catch the prevailing wind,” says Tom. “And the majority of the time, the wind is from the southwest, so the bedding in the southwest part of the barn will be heavily used and will have to be spread around more. It’s little things like this that dictate the life of the bedding.”
The bedding cycle for the Portner farm—and both Tom and Mark emphasize these numbers are subject to the size and variables compared with other dairy operations—is that 120 cubic yards of bedding will last 18 days during the winter months in their first barn, with up to 62 cows. Through the spring and the summer months, the pack will last up to 45 days. This past spring, that was shorter because they had a lot of rain, 22 inches, over a fairly short period of time.
“How long the pack lasts is not an exact science,” notes Tom. “You have to read your bedding pack. There are times when I order bedding and when it shows up, I don’t need it yet because the weather has changed. We’ll get sudden warm, dry days and be able to spread the pack out and it’s good for a couple more days.”
And the cows love fresh bedding, of course. But the cows also like it after Tom or Mark put in a bit of extra time mixing the bedding up with the skid steer, pulling more dry material out.
In terms of the overall barn size, Tom says they are more concerned about whether there is enough room for all the cows to lie down, rather than any specific square foot formula. “There’s always a time of day when you can find the herd, with the exception of maybe one or two cows, all lying down. You don’t find that in a freestall facility, no matter how comfortable they are.”
Thinking of composting bedding? Find a bedding source first
Tom Portner has one overriding piece of advice for anyone considering composting bedding for their dairy facility. “The number one thing we tell people is that if you don’t have a bedding source, don’t even try doing this. Find that bedding source before you commit to this type of housing.”
In the case of the Portner dairy, they already had a supplier who was providing them with coarse
sawdust, and it was a matter of changing over to the fine sawdust that seems to work best.
“The real trick is to get a good quality, consistent product and to find a source that is going to supply you right through the year when you need the bedding, regardless of whether there is an oversupply of sawdust or if it’s really in demand.”
The Portners have found that the finer the sawdust is—and the emphasis should be on “dust” because that is about the consistency of the product they use—the better. “The finer material works best. It is denser, holds more moisture and it mixes better with the manure. “It really is dust, there are no shavings. It’s as fine as you can get it.”
These happy cows are turning in good production numbers. They are also healthy. “Our goal is to keep the cows as clean as possible,” says Tom. “In the process of doing that, we have also created an aerobic type of respiration in the sawdust that is creating not exactly a true compost, but some of the characteristics of a true compost are created while we are housing the cattle. We don’t manage the bedpack to optimize it as compost material. To do that, we wouldn’t stir it as often.”
The twice-daily stirring reduces the heat build-up in the bedpack, cutting down on the composting aspect. But Mark notes there is still a good amount of heat in there. “There are times in the winter when we can’t see the front end of the loader when we’re stirring, because of the cloud of steam hitting the cold air.”
When they set up compost bedding in their recently built 54 foot by 224 foot barn this past summer, they put about 120 cubic yards of sawdust in, using one of their two Gehl skid-steer loaders. The actual bedding pack area is 42 by 184. A small area at the back of the barn can house about a month’s compost/manure mix.
In building the barns, they opted for a 16-foot high sidewall with the second barn, versus 14 feet with the first barn. This provides a bit more area between the truss-mounted fans and the cows on the manure pack. In the new barn, they have mounted a dozen H&D 36-inch fans.
They also placed the water fountains at the outside of the feed alleys, rather than the inside. They found that water sometimes slopped out in the alley way, freezing in the Minnesota cold, making it harder to keep clean.
On the crop side, the proof is in the doing with the compost bedding. The first time they had crops off the ground with bedding pack applied, it was right beside a neighbor’s land, which allowed them to do a direct comparison.
“Our ground had been fertilized with manure over the years, so I can’t say that all of the growth was due to the bedding pack, but our soybeans were about a foot taller,” says Tom. He added that while the yield might not be as great as the height indicates, it definitely indicates an increase.
Commercializing composting an option
While the bedding from the Portner dairy farm is being used on cropland for the Portners, and their neighbors, Tom and Mark Portner admit that it sometimes looks attractive to commercialize the process. “It intrigues us, especially when you see what compost is going for at the store,” says Mark.
If that does happen, it would be part of a broader expansion of the farm, and there are other factors involved. Their farm site is pretty full right now, meaning there would not be a lot of space for putting the material into windrows to complete the composting process. They might have to build covered structures to facilitate the composting process. And then there is the investment in handling and bagging equipment, marketing the product, and serving a whole different set of customers. It is, says Tom, “a completely different business than the dairy side.”
The Portners are currently working to incorporate new state regulations regarding the amount of nitrogen applied to soil—farms will be allowed 125 pounds of nitrogen per acre over a two-year period of time. “We are carefully planning now where and when we are putting the material. We need to have a game plan for a two-year rotation, and when and what we want to incorporate.”
To make application more practical, they have buffer strips along drainage ditches and water bodies that allow them to better utilize land for manure application. “The regulations call for being 300 feet from a drainage ditch, and without those strips we could not apply manure to a lot of our land. We’d have to incorporate a lot of it.”
The Portners are working with researchers from the University of Minnesota to better pinpoint the amount of nitrogen in their manure, and how quickly it releases. Preliminary results show a 50 percent first year, 50 percent second year release. They will be utilizing those numbers, along with data about the soil on their land, to better tailor the application of manure to the land.
“These new regulations are a significant change,” notes Tom. “It’s forcing us to be more diligent in what we are doing and putting on the soil. It’s no longer a matter of putting some manure here and there; it will allow us to understand our soils better so we can become better managers for manure management and the crops.”
The regulations seem to be a good fit with the overall plans and approach of the Portners, however. “Our goal is to be in the dairy business longer term. In order to stay in this business, you have to be a good steward of the land.” It is good common sense, and business sense, to be approaching things in an environmentally progressive way.
“We need to be working with the land, not fighting it,” says Tom. “As an industry, we understand how to feed the cows. Do we understand how best to feed the plants? There is still so much more to learn.”
And sometimes learning means being innovative at both ends of the cow. For example, the Portners feed their cows brewery waste from the Schell’s brewery in nearby New Ulm. Using this material means they don’t have to include haylage in the feed ration. “It makes use of their waste product and for what we pay, it’s extremely cheap for the energy and protein we get in that product.”
The fact that they apply manure to neighboring land means they have options in terms of when and where to apply the manure. With rented land, the Portners have a total of about 500 acres, which they apply the bedding manure mix to, in addition to 300 acres of neighbors’ land. They use a Kuhn-Knight model 8132 ProTwin slinger spreader, with a capacity of 3,251 gallons.
|The bedding cycle for the first Portner barn is that 120 cubic yards of bedding will last 18 days during the
winter months, with up to 62 cows. Through the spring and summer months, the pack will last up to
Tom notes that while they have a smaller dairy operation, with about 130 cows, there are larger, 500-cow facilities that are also looking at compost bedding. And he adds that while the system they have developed works very well for them, “every barn has its own different characteristics with its dimensions and design.”
“We’re glad that compost bedding works for us and we’re happy to return the favor Calvin Paulson extended to us, and pass on information about how the system works for us here in Minnesota.”
Compost bedding may not be for everyone—Tom notes it really is just another option—but it has a lot of interest, judging by the steady number of visitors to the Portner dairy farm. “It seems to have really got a lot of people’s interest. You could never sit down and strategically plan to create the buzz and interest compost bedding has created on its own.”
Tom Portner adds that overall, employing compost bedding has been a bit of an education, with both Mark and himself learning as they go along. “What we do now is different from what we did in the first year of operation. And we learned things from the first barn that we used in the second barn.”
They are already thinking ahead, to their third barn. The wiring and piping has been set up in the new barn so that it could easily accommodate an adjacent third barn. “We like to use as much foresight as possible in planning things out. There are enough surprises in this business as it is.”
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