Extension Ag Update
January/February 2011
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Herbicide Survey of Grass Hay and Straw Producers

Ellen Phillips, Extension Educator, Countryside Extension Center, ephillips@illinois.edu, 708-352-0109

How can herbicides end up in compost? In 2009, passage of SB099 into law, now allows up to 30,000 cubic yards of livestock waste per site to be incorporated into composting systems along with yard waste and food waste. In addition, many local farms and stables compost manure. This is a good way to add value to manure. In 2008, the 39 compost facilities in Illinois altogether processed 497,421 tons of landscape waste, a 24 percent increase from 2007. It is expected that this will continue to rise as more composting facilities are approved. However, the addition of manure to compost can be a concern for landscapers and others who utilize compost for seeding mixtures.

Pyridine herbicides (Forefront, Milestone, Curtail, Stinger, Grazon P+D, Surmount, Redeem R&P, Crossbow) are quite persistent and are not easily broken down. When animals eat hay or pasture grasses treated with pyridine herbicides, it takes about three days to pass through the animal and the herbicides remain active in the manure. Treated bedding straw picked up with manure also remains active. When the manure and straw are used in a compost system, the herbicide remains active in the fresh compost. This can cause problems for landscapers, etc. wanting to use composted manure for seeding mixtures. Plant injury symptoms include malformed growth, twisting, and bending. Dow recommends “Aminopyralid is degraded in soil when it comes into contact with soil microbes, but it degrades very slowly in manure or compost. Do not rotate any field treated with herbicides that contain aminopyralid within one year following treatment, and not until an adequately sensitive field bioassay shows the amount of herbicide present in the soil will not adversely affect the rotational crop.”  (www.manurematters.com)

To determine the extent of this possible problem within Illinois, a survey was conducted in the spring of 2010 to estimate the tons of pyridine treated hay and straw used in Illinois. Twenty-eight responses were received. All responses were for hay, none dealt with straw. About 92% indicated that the treated hay was used on farm and not sold. Seven percent indicated the hay was sold to beef producers. Only one percent indicated hay was sold to horse stables. This would indicate that the potential for manure with herbicide residues reaching composting systems is limited.

Composting is a viable option for adding value to manure. If treated hay is being sold off farm, producers are encouraged to discuss the potential for herbicide injury with the consumer. If the manure is being hauled to a commercial composter, the composter should be made aware of the potential for seedling injury. Farmers utilizing manure with herbicide residuals on their own operation should be cautious about the fields where they are spreading it.