Copper sulfate is the most cost-effective treatment for controlling hairy heel warts that cause lameness in dairy cows. The copper sulfate used in the cows' footbaths is disposed of in manure slurry applied to farm fields. A Miner Institute survey of New York and Vermont farms estimates that four to 16 pounds of copper sulfate is applied per acre per year. The New York State Department of Environmental Conservation has set a lifetime load limit for copper at 74 lbs/acre. Depending upon the application rate, a field could reach its maximum load of copper in 4.5 to 19 years. Over those years, a farmer hopes to harvest maximum crop yields.
A team of researchers funded by the Northern New York Agricultural Development Program are evaluating timothy and orchardgrass grown in greenhouses using controlled applications of copper sulfate on sandy loam and silt loam soils at the William H. Miner Agricultural Research Institute in Chazy, NY. A field study on corn is now underway at the Institute.
"What we want to know is how much and how well copper sulfate is tolerated by field crops," says research team member Everett D. Thomas, vice-president of agricultural programs at the William H. Miner Agricultural Research Institute. "We know of no research that determines how copper in sulfate form affects crop development on different soils. The data from our project will determine how the rate of copper sulfate application affects root growth, forage quality and yield."
Thomas says farmers can consider several alternatives to reduce their use of copper sulfate to obtain desired crop yields and guard cow foot health. Those alternatives include adjusting the amount of copper sulfate used in footbaths, reducing the frequency of footbaths, using them less in the winter, and improving hoof trimming and stall surfaces
Miner Institute was able to reduce its use of copper sulfate by 60% and maintains its dairy herd's hoof health through good hoof trimming practices and use of rubber mats throughout the milking barn.
While Thomas says it is too early to release results, "some of the results from the greenhouse study on the forage grasses were eye-opening - big yield decreases where copper sulfate was used." He is eager to see the field corn study results.