By Jody Padgham, MOSES
With cold weather on the way, farmers with animals are setting up their winter feeding systems. One important issue to consider when exploring options is how the manure will be managed. Feeding means congregating animals in one place, and that means the collection of manure in a centralized area. This is something folks who have grazing animals generally don’t have to think about during the green part of the year, as the animals are naturally dispersing the manure as they move through paddocks and pastures. A natural concentration of nutrients, manure in any congregated form must be managed carefully.
One option is to set up animals in a bedded pack system. With bedded packs, large amounts of some kind of bedding are put into a confined (often covered) area. The animals are allowed to lounge and eat in that area, and the bedding is either turned mechanically to create a composted bedded pack, or added to and allowed to accumulate in a simple bedded pack.
Jim Greenberg of Greenberg Farms, LTD in Stratford, Wis. has had his 550 organic milking cows and the dry and young stock on composted bedded packs since 1994. A few years ago, he built a 160 ft. by 660 ft. Coverall building to hold the pack and cows, as well as some hay storage. A concrete floor and tall side walls accommodate the 4 to 5 feet of pack that accumulates by spring. The original pack, in a large lean-to shed, is still used nearby by the young stock and dry cows.
Value for Manure Management
“With our farm right on the outskirts of our village, the composted pack is an important manure management tool,” Jim says. “We don’t want to be spreading liquid manure.” Using rotational grazing for half the year, Jim doesn’t want any smell from winter manure accumulation and spring spreading to disrupt the bucolic atmosphere of the town. Jim also appreciates the quality of comfort for the cows, and maintenance of cow health and milk quality through potentially stressful winter months.
The composted pack starts with about a foot of kiln-dried sawdust spread on the cleaned concrete floor. Pack from the previous year is not reused, although 8 inches to a foot of the old pack is taken off and integrated into the new pack to “inoculate” the bedding with bacteria. “The inoculation really helps to start the bacterial action each year,” Jim says.
Cows are brought in at the end of the grazing season and allowed to lounge in the comfortable bedding. Twice a day, when the cows go into the parlor for milking, the farmers stir up the top 8 inches of the pack with a spring-tooth drag. Three times a week, they add new bedding. Jim explored different kinds of bedding, but has found that kiln-dried sawdust works the best. “We’ve tried hay and straw, even cornstalks, but it is hard to get the quantities we need and the material must be very finely ground to work properly,” he says. The farm gets semi-loads of sawdust delivered from nearby mills.
In the composting system, the bedding heats up as the cows add manure and the stirring adds oxygen. “We see temperatures of about 110 degrees,” Jim says, “not enough to be called compost according to the Organic Rule, but enough to really break things down.” The warmth is nice for the cows, too, during the cold Wisconsin winter.
Success with Careful Management
There is an art to managing the pack, as variables such as weather affect how much additional bedding should be added. “We’ve found it is best to keep the pack a little drier than many people recommend,” Jim says. He tests the moisture by digging in 8 inches and squeezing the material; he likes to see only 50-60% moisture. A lack of attention to the balance of moisture can create issues with milk quality, which is some operators’ complaint with the system. “If the bedding is sticking to the animals, it is too wet, and there can be problems with somatic cell count. The pack should always look dry on top,” Jim explains. Dry weather means less bedding will be needed; wet snow or fog causes reduced evaporation from the pack, and a need for more sawdust.
Throughout the winter, the farmers scrape the alleys and pile up excess material in a nearby yard. They turn these piles four times during the summer, and in August haul them out to next year’s corn fields. Once the cows go out onto pasture in May, the pack in the Coverall and shed is allowed to rest. It will decrease in volume by about a foot over the summer. In October, right before the cows come back off pasture, the areas are cleared out and the bedding mixed with manure is spread on crop land. It lays on the land over winter and is tilled in in the spring. “I believe that the sawdust ties up the nitrogen, and so we don’t grow super corn, but the carbon breaks down and we have seen a real increase in soil fertility and organic matter as the compost material slowly breaks down,” Jim claims. Soil tests on every five acres every four years have proven the value of the compost to the soil.
Jim recently did calculations to see what the system cost for his 550 cows and additional dry and young stock. His estimate of 6 tons of sawdust per cow per year comes to $2.15 per cow per day. “This system isn’t cheaper than a free-stall,” Jim says, “but we prefer it for the environmental reasons. We can spread the manure anytime and anywhere.”
Non-composted “simple” packs work on most of the same principles, but are not stirred and use a larger quantity of bedding. In these systems diverse bedding can be used–including straw, old hay, mature grass, even goldenrod. Non-composted packs will be 6 to 8 feet deep, almost twice what the composted pack will be at the end of the winter. In these systems the holding area is cleaned out in the spring, the bedding placed into windrows and turned several times to create compost, which is then applied to fields in the fall. Depending on where the bedding material is obtained, simple packs can be more cost-effective, and take less day-to-day management, but do create more material to be managed at the end of the winter.
As excellent systems for managing manure, bedded pack systems will generally qualify for support from the Natural Resources Conservation Service (NRCS) with cost-share dollars. The publication “Compost-Bedded Pack Barns in Kentucky” has comprehensive information on all of the considerations in building and managing a bedded pack system. Information about simple bedded packs from Cornell University can be found at here.
Jody Padgham is the MOSES Organic Broadcaster Editor.