Herbicide carryover in compost, hay and manure
Do you know some herbicides used in the pasture tend to be active for several years as they can get carried over to hay, compost, and manure? It sounds strange, but when fed with herbicide-treated hay, livestock can pass the residual herbicides down to the manure. Even after composting, some persistent herbicides do not break down quickly enough. Unfortunately, contaminated farm byproducts, when applied on the farm, affect crop yield and growth. The herbicides in question are in the pyridine carboxylic acid class of broad-leaf herbicides. Some of the commonly used herbicides in this class are aminopyralid (Milestone), clopyralid (Tansline), and picloram (Grazon). They are registered for application to pasture, row crops, orchards, and lawns and are effective herbicides for broad-leaf weed control. However, these herbicides have long residual activity (3+ years) compared to phenoxy herbicides, such as 2,4D, which break down in a few months.
