As winter’s snowfall and freezing rain gives way to warming temperatures, rapid melting and potential for flooding pose challenges for manure management among the more than 25,000 livestock farms in Minnesota, warns the Minnesota Pollution Control Agency (MPCA). Farmers who spread solid manure during winter must ensure that it doesn’t run off with rapid snowmelt flowing to ditches, streams and other waters.
Manure-contaminated runoff not only threatens water quality, it reduces the value of manure as a crop nutrient. If possible, farmers should refrain from spreading manure during periods of rapid melt. This may be even more important in some areas this year because of frozen snow conditions. In January and February, the snow was saturated by rain and then froze. This prevents surface-applied manure from soaking in to the soil and more susceptible to runoff.
Minnesota rules require a 300-ft. setback from surface waters and open tile intakes for all manure spread onto frozen or snow-covered soil. However, this spring the MPCA encourages farmers to refrain from surface application until the snow and ice layers are melted. “We have already had several cases where manure was applied in accordance with the rule, but has negatively impacted surface and groundwater a significant distance away,” says Wayne Cords, MPCA feedlot program supervisor.
If manure land application can’t wait, to reduce the impact of manure applied to the surface of wet, frozen or snow- covered soil, choose the flattest field or flattest parts of fields and follow these guidelines:
- Field slope should be less than 6% slope for solid manure, 2% for liquid manure.
- Do not apply non-incorporated manure within 300 ft. of surface waters. If possible, apply manure at even greater setback distances.
- Do not apply manure in areas of the fields that contain other areas of concentrated flow. A 300-ft. setback is required for intermittent streams; however, most fields also contain other areas such as grass waterways that receive concentrated flow. Keep back as far as possible from these other areas of concentrated flow.
- Choose fields that contain the most crop residue; greater than 30% is recommended.
- Avoid applying to fields where the furrows are full of ice and snow.
- Keep application rates low enough to avoid runoff or ponding during application.
- Choose fields that do not have adjacent non-tillable land containing areas of concentrated flow such as ravines, ditches with open side inlets, streams or dry runs. If this isn’t possible, stay away as far as possible from these off-field areas of concentrated flow.
Livestock farms that experience manure runoff into waters of the state must report to the Minnesota Duty Officer by calling (800) 422-0798, and take immediate action to reduce environmental impact, such as creating temporary berms to stop discharge, temporarily plugging culverts and drain tile intakes to prevent manure inflow, and soaking up liquid with absorbent material, such as hay, straw, cornstalks or wood shavings.
For more information, see the MPCA fact sheet, Managing Manure and Land Application During Adverse Weather Conditions. You can also contact your county or MPCA feedlot staff,or call the MPCA at (800) 657-3864.