Handling pastured cattle through winter and early spring is an annual dilemma for most farmers. Sacrifice, or outwintering areas are the answer for most, but unless such areas are properly engineered, the potential for damage through pugging or liquid runoff is high.
Dr. Joshua Faulkner, Farming and Climate Change Coordinator at the University of Vermont, has been working with several farmers in New England who have constructed wood chip sacrifice areas. Faulkner first tested the concept in West Virginia, where the beef industry is similar to that in New England; with relatively small farms scattered throughout the region.
Faulkner says farmers are aware that confining cattle for part of the year makes them subject to environmental regulations, so some were intentionally not confining animals. The result was damaged pastures and negative consequences for forage growth in spring and summer.
“We were looking for a solution for the winter season,” said Faulkner. “Cows are out on grass during spring, summer and fall, and they’re brought back in for winter feeding. There’s some level of confinement or keeping them closer to the barn. We saw some environmental impact in the sacrifice areas that had water close by, and wanted to address that with a solution. We knew that the rules around the Chesapeake Bay TMDL (Total Maximum Daily Load; the maximum amount of a pollutant that a body of water can receive without compromising water quality) were coming fast and there would be more pressure on small farms in the future.”
The goal was to find a solution that would limit the environmental impact and create an area that farmers felt good about putting their cattle on. “Some farmers weren’t too enthusiastic about putting cattle on concrete, which was one of the solutions offered,” said Faulkner, “so we started to look for a solution that met the challenges.”
Faulkner says Tom Basden, nutrient management specialist at West Virginia University, learned that wood chips were being used for overwintering areas in the U.K. and Ireland. Basden and Faulkner researched the concept then constructed some wood chip pads in West Virginia to test the concept. Faulkner is now actively promoting the concept in Vermont and other New England states.
The practice involves more than simply dumping wood chips onto a surface to soak up moisture. It’s a carefully engineered project that starts with the excavation of topsoil, followed by the removal of another foot of subsoil. The excavated area is shaped into a ridge and valley design to encourage drainage. Perforated drainage pipes are placed in the valleys in the subgrade, and filled with about 12 inches of gravel for drainage, topped by 10 to 12 inches of wood chips. A small berm is formed around the lot so outside water doesn’t come onto the pad.
Not just any chips will work for a wood chip lot. “Wood chips should have the fine material screened out because that will tend to clog the pores of the drainage system,” said Faulkner. “We try to use whole, round wood if we can — wood from the trunk instead of smaller branches.” Faulkner says the ideal chip is a bole, or heating chip, made for schools, hospitals and other large facilities that use wood heat. Chips collected from tree work can be used, but should be screened to eliminate any green or small branch material.
Siting is an important consideration for wood chip lots. All of the wood chip lots have been constructed in existing sacrifice areas or barnyards where cattle were already confined. “They’ve all been directly adjacent to a new roofed winter feeding structure or barn of some sort, or an existing one,” said Faulkner, “and we prefer to build on a relatively flat area.” Faulkner added that a slope of more than a few percent would probably lead to chips migrating downhill due to hoof action and gravity.
Faulkner noted that about 2/3 of total manure is deposited where cattle eat, so wood chip areas should include a feeding pad. A small concrete pad for round bales or a feed bunk keeps the wood chip pad cleaner, and the top layer of chips will last longer if the manure is evenly distributed.
Both hardwood and softwood chips have been used for chip pads. Research with various species of hardwood chips showed that hardwoods performed similarly to one another. “We’d like to compare hardwoods to softwoods,” said Faulkner. “Two of the pads in Vermont have used a fair amount of softwood, and we’re thinking that’s okay, but those chips may break down faster than hardwood. Softwood may also be more absorptive of incoming rainfall, where hardwood offers less absorption; resulting in more drainage water. That’s a big cost consideration — how drainage water is handled — so being able to absorb more water is a good thing.”
The general maintenance recommendation is to scrape off the top three inches when cattle are removed from the lot. “That’s where most of the manure is bound up in the chips,” said Faulkner. “We scrape that off and compost it, then it can be applied as a nutrient to hay fields or pastures. Then we apply a new layer of chips to the pad. We think that cycle, with the annual rejuvenation of two or three inches, will last at least a few years. We haven’t hit the situation yet where we need to dig out the entire chip bed and replace the deep chips.”
For the small amount of drainage water that might result in spring, vegetative buffer strips or grass filter strips are an option. The cost of a holding pond is high, but might be necessary in some cases. If a farmer determines that the wood chip pad isn’t working effectively on his farm, or if chips become difficult to obtain, there’s still a good base of properly prepared gravel to finish for a heavy use area.
The chip pad is most suitable for beef cattle, dairy calves and heifers on mixed forage rations over winter through early spring. Studies to evaluate animal health have not been conducted, but U.K. work indicates no issues with hoof health. In New Zealand, chip pads are not recommended for lactating dairy cattle because dairy manure is more liquid and heavier in volume. Faulkner says some of the U.K. studies show weight-gain benefits for beef cattle. “Farmers are interested in animal comfort and increased performance,” he said. “Farmers also want to be proactive regarding current and potential TMDL regulations.”
As more chip pads are installed, Faulkner will continue to collect data and make that information available to farmers. He hopes to spread the word about how chip pads can benefit both the farmer and cattle through field days where farmers can discuss the details and benefits with the host farmer.
“There’s a healthy forest industry in the northeast, said Faulkner. “I’m thrilled we can interact with them and benefit both farms and forests.”