What is your winter manure strategy?

Dairy farmers should develop a strategy to define where late winter manure may be spread with limited runoff risk.

Even in the winter months, Michigan dairies are faced with many tough decisions. If producers did not get enough manure spread last fall they may need to look to winter spreading to ensure they don’t run out of storage space before spring. Manure can be a valuable resource for livestock farms even in the winter, but Michigan State University Extension reminds farmers that it is important to recognize the risks associated with winter spreading and to develop a plan to address those potential risks.

What is considered winter manure spreading?

No matter when it happens, once Michigan receives its first major snowfall of the year, along with dropping temperatures, dairy farms are thrown into the frozen or snow-covered ground period for spreading manure. Most producers will try to get manure spread into the fields in the fall after harvest. There are times, though, when winter manure spreading is unavoidable. For example, farms may choose to winter spread if their manure storage is full and will overtop unless some manure is taken out. On some farms, animal numbers are on the rise and their storage capacity remains the same which could lead to needing to winter spread. Many livestock facilities were built to require some sort of periodic removal of manure – daily, weekly, etc. even in the winter months. Research has shown that runoff on frozen ground occurs earlier than one might expect. As winter transitions to spring, runoff is beginning to happen in January, February and March.  

What are the risks of winter manure spreading?

Winter manure is often surface applied, the feasibility of incorporating or injecting manure diminishes with frozen ground and surface applications are vulnerable to random weather events. Weather conditions will create times when surface water runoff is very likely and inevitable. Examples of circumstances that greatly increase the risk of loss include: the presence of concrete frost, development of an ice crust on the soil surface, and the amount and condition of the snow cover. The worst case scenarios being either rain on frozen ground or snow melting so fast that runoff occurs before the ground can thaw and take in the moisture and manure. The key to reducing nutrient loss during winter spreading is to understand the local conditions and have a winter spreading plan in place.

What are winter manure management strategies?

From a manure management standpoint, where and when the manure is applied can have a large impact on the risk to surface water quality. Dairy farms that depend on daily, weekly or periodic hauling should try to apply manure to fields with a higher runoff risk (closer to water or steep slopes) early in the winter when the risk of runoff is lower. This allows fields with a lower runoff risk (more distant from water or flatter slopes) to be held in reserve for late winter manure application when there is an increased environmental risk. Michigan Right to Farm Generally Accepted Agriculture Management Practices for Manure Management and Utilization states that solid manures should only be applied to areas where slopes are six percent or less and liquid manures should only be applied to soils where slopes are three percent or less. The GAAMP’s also suggest manure should not be applied within 150 feet of surface water, a catch basin or area of concentrated flow.

Another good winter manure spreading strategy is to define winter spreadable fields. Farmers depending on winter spreading should develop a strategy where fields under consideration for winter spreading are defined by environmental risk. The Manure Application Risk Index (MARI) helps determine the winter manure application risk on a field by field basis. Assistance with MARI is available to Michigan farmers through their local Michigan Agriculture Environmental Assurance Program technician or Conservation District office. Winter spreading plans should be followed by everyone involved, particularly the person driving the tractor and spreading manure.