Manure Stewardship: Late Winter Manure Application and Risk

Angela Rieck-Hinz, Extension Program Specialist, Department of Agronomy

There are many definitions of stewardship, but a basic definition is "the responsibility to care for resources." When applying the term stewardship to manure management we could define it as the "responsibility to collect, transport and apply manure to meet crop nutrient needs while minimizing impacts on resources."

Manure application timing is a big part of stewardship and one concern with timing is the application of manure in late winter. In the most basic terms — manure should not be applied at this time of year. This statement applies to all sources of manure.

As we head into late winter most of Iowa has significant snow cover. With the warming trend that is predicted for the first week in March, it is likely we will lose significant snow and with the snow loss comes a very high risk of losing the manure with the snow. Nutrient loss from runoff can be significant thereby rendering those manure nutrients useless for crop production and consequently causing stream and surface water pollution. If we are going to use manure as a nutrient source for crop production then we should consider protecting that nutrient investment at all costs by limiting the risk of nutrient runoff. 

With that being said, there will be people who continue winter application of manure, and for a variety of reasons. If you must apply manure in late winter:

• Consider applying on flat slopes.
• Apply as far away from surface waters as possible.
• Follow all required separation distances.
• Avoid application on areas that drain to surface tile inlets. 
• Do not apply manure in a grassed waterway. 
• Wait until the snow melts.
• Avoid application prior to predicted rainfall, snow of warming conditions that could cause snow to melt or runoff.  

Please see IMMS, Volume 3 "Winter Manure Application" at  for additional guidelines.

Be aware that application of liquid manure from confinement feeding operations is prohibited on snow-covered and frozen ground from now until April 1 unless an emergency exemption applies or the manure can be appropriately incorporated into the soil.

Finally, if you participate in USDA-NRCS cost-share programs or receive technical assistance from USDA-NRCS, be aware that the 590 Nutrient Management Standard does not allow nutrient application if runoff potential exists unless you meet the emergency exemptions in the 590 standard. The 590 standard applies to all sources of nutrients, not just manure.

Angela Rieck-Hinz is an extension program specialist for Iowa State University Extension and is the coordinator of the Iowa Manure Management Action Group (IMMAG). Rieck-Hinz can be reached at (515) 294-9590 or by emailing amrieck@iastate.edu.