Most producers would prefer to spread manure on their fields in spring and summer when the crops are going to get the most use out of it. Although the Department of Environmental Protection discourages winter manure application, there are circumstances when manure has to be applied in the winter, such as when wet fall weather kept field conditions unsuitable and the lack of a large enough storage structure to hold the manure until spring. Because of these circumstances, the Department of Environmental Protection’s Manure Management Manual provides winter application criteria. When winter application must be done, producers need to be aware of and follow the winter manure spreading criteria in the Manure Management Manual. It is important to note that horses are also considered livestock, so horse owners must follow these winter application criteria as well.
According to the Manure Management Manual, winter is defined as any one of the three following times: Dec. 15 through Feb. 28, or anytime the ground is frozen at least 4 inches, or anytime the ground is snow covered. If it is necessary to apply manure during any of the three previously mentioned times, the following information outlines the criteria you will have to meet.
First, there are maximum rates of application set for winter spreading, which are 5,000 gallons per acre of liquid manure, 20 tons per acre of dry non-poultry manure, or 3 tons of dry poultry manure per acre. Secondly, fields that receive winter manure applications must have at least 25% crop residue cover or an actively growing cover crop. According to the Manure Management Manual, fields with less than 25% crop residue going into the winter would include ones taken for corn silage, low yielding soybean fields and corn grain fields where a significant portion of the fodder has been removed. The Manure Management Manual goes on to state that hay fields, sod, pasture fields and fields with an actively growing cover crop should be given the highest priority for winter manure application.
The next guideline to remember is the fact that fields with greater than 15% slopes are not acceptable for winter manure application. The printed NRCS Soil Survey (or the NRCS Web Soil Survey online) is a great place to look to see if your fields have less than a 15% slope. Soil slopes are defined by letters at the end of the abbreviated soil type on the NRCS Soil Survey map. So, slopes designated as A, B or C are acceptable for winter manure application.
Finally, when spreading manure in the winter, there is a required 100-foot setback from ponds, lakes, tops of stream banks and above ground inlets to agricultural drainage systems where the surface water flows toward the inlet. In addition to these 100-foot setbacks, manure applications are also required to stay back 100 feet (every day of the year) from existing open sinkholes, private drinking water sources and public drinking water sources. In some cases, state and federal laws may require a larger setback for public drinking water sources. Another Manure Management Manual criteria that is in place year round is that manure is not to be spread within the channel of a non-vegetated concentrated water flow area, such as a swale, gully or ditch. This does not include grassed waterways because they are vegetated.