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Best practices reminders for fall activities

Fall is a great time to evaluate ways to maximize the nutrients in your soil and protect water quality. To get the most value from manure as fertilizer and to avoid manure runoff that could pollute waters, the University of Minnesota and Minnesota Pollution Control Agency (MPCA) recommend the following best management practices, related to manure application.

Soil temperature matters
Delay manure applications on coarse textured soils until soil temperatures are below 50 degrees F. Applying manure in late Oct./early Nov. will reduce potential nitrogen loss. Cool soil temperatures slow down the chemical reaction process that transforms the nitrogen in manure into nitrate that is susceptible to leaching into water. This is known as nitrification. To maximize nutrients, the cooler the soil at the time of application, the better. (See graph below.) 

Soil temperatures under 50 degrees F maximizes the manure nutrients entering soil.

Field trials by the University of Minnesota Extension Service routinely see a 10 to 15 bushel/acre yield increase when manure applications occur in early Nov. compared to early Oct.. The Department of Agriculture’s Six-inch Soil Temperature Network tool can provide real time soil temperatures for your area.

If you can’t wait until late fall when soil temperatures are below 50 degrees F:

• Use cover crops to protect. Consider planting a cover crop on harvested fields before or within 14 days after applying manure in Sept. or early Oct.. Plant roots will help your soil retain the essential nutrients needed from the manure.
• Apply a nitrification inhibitor. This additive slows down the nitrification chemical reaction and can reduce nitrogen loss. Nitrogen inhibitors are influenced by soil temperatures and moisture and are only effective for approximately two weeks, so using this additive could allow application a few weeks prior to when the soil temperatures drop below 50 degrees F.

Consider erosion and runoff
Avoid applying manure to highly erodible fields with slopes or sensitive features unless manure can be immediately incorporated into the soil. Take weather into consideration for your application timing and wait or reduce your application rates if field and weather conditions are not ideal. The Minnesota Department of Agriculture’s Runoff Risk Advisory Forecast tool can help determine the best time to apply manure to a field.

• Remember water features, such as lakes, rivers, streams, and protected wetlands can be impacted by manure runoff. If the runoff risk forecast is moderate or severe, applicators should reevaluate the locations or dates for applying manure.
• If water features or other sensitive areas like open tile inlets, sinkholes, and drainage ditches are in your field or within 300 feet of your field’s boarder, manure must be incorporated within 24 hours and before rainfall.

Review your manure application rates
Evaluate last year’s application records with consideration of your crop rotation. Proper manure application rates help ensure your meeting next year’s crop nutrient needs. Visit the University of Minnesota Extension’s manure management web page for help in calculating manure application rates.

Promote safety first

• Check your equipment. Manure spilled or leaked on public roads must be cleaned up, so check your manure hauling equipment for broken hoses, loose connections, leaking valves and gaskets.
• Stop, report and recover spills immediately. When spills happen, be sure all personnel are safe then immediately stop, report and recover the spill. Report your spill any time of day to the Minnesota Duty Officer at 1-800-422-0798. Keep the information basic and give the officer your location. The duty officer will contact local authorities.
• Helpful tips for spills. Close a valve, drive a vehicle onto a drag line hose, or turn off a pump. Use tillage to slow spill movement toward sensitive features in fields, build dirt berms, or use hay, straw, or corn stalk bales to absorb the spill. Plug culverts and open tile intakes. Contact a septic hauler to vacuum up any visible puddles of manure.

If you use a contractor, be sure to discuss these best practices with them before they arrive. Try to provide the hauler with a copy of your field maps that show sensitive features and note the manure application rate for each field. But most importantly, make sure they know what to do in case of a spill.

This is also a good time to review your current permit for any additional restrictions or contact your county zoning department for questions about possible application locations.

For additional information, visit the MPCA website at https://www.pca.state.mn.us/business-with-us/land-application-of-manure or contact your County feedlot officer.

The mission of the MPCA is to protect and improve the environment and human health.

St. Paul • Brainerd • Detroit Lakes • Duluth • Mankato • Marshall • Rochester

www.pca.state.mn.us • Toll-free and TDD 800-657-3864