By Diane DeWitte, UMN Extension swine educator
Written for submission to The LAND - as March 2, 2026 Swine & U column
Last week, for a minute, it seemed like spring was here; then it rained, and the next morning we were shoveling a path to the barn. Never fear! March is around the corner, and with it an opportunity to get manure hauled out of the barns.
Maybe your manure plan involves fall application, but as the soils thaw and the tiles begin to run, it’s a good idea to review a few environmental protection habits which will help keep nutrients where they belong.
University of Minnesota Extension provides good resources for nutrient application calculation and groundwater and shoreland protection at its manure management website. Extension manure management specialist, Melissa Wilson, and manure management crops educator Chryseis Modderman provide the latest best management practices for manure application in our Land of Ten Thousand Lakes and Nine Million Pigs.
Summer application is also an option. Dr. Wilson’s research has shown that directly applying liquid hog manure into growing corn can be successful; Injecting manure between the young rows provides maximum nutrient value, but specialized equipment is needed.
Livestock manure is a valuable source of crop nutrients, but it can also come with pathogens that may cause livestock and people to become ill. The number and type of pathogens in manure vary based on animal species, feed, and animal health. There are many different types of pathogens in manure, so using multiple best management practices at once will give the best results.
Common bacteria found in livestock manure include Campylobacter, E.coli, Leptospira, Salmonella and Yersinia. Rotavirus is the most prevalent virus found in manure, and Cryptosporidium and Giardia are protozoa found in livestock manure and pet feces.
Modderman points out three main areas of focus where livestock producers can reduce pathogens:
Pathogen concentrations decrease when exposed to UV light and drying. Since that naturally occurs when manure is surface applied, delaying manure incorporation will reduce pathogen numbers. However, waiting to incorporate manure can have adverse environmental effects as nitrogen is lost to the atmosphere and runoff risk is increased. Flies and vermin are also more likely to pick up and carry pathogens from manure that is left on the surface. Therefore, the recommended method is to incorporate manure soon after application.
It predicts the likelihood that applied manure will run off fields in daily, next day, and 72-hour increments. Farmers and commercial applicators use an interactive map to locate their field and find the forecasted risk. MDA offers a ‘sign-up’ for Runoff Risk Alerts at this link: https://public.govdelivery.com/accounts/MNMDA/subscriber/new?qsp=MNMDA_3
Alerts will be sent via email or text when conditions are likely for a runoff event.
Dr. Cortus emphasizes that even though only a few folks from on or off the farm actually pump and haul the manure, it’s critical that everyone on-farm understands the dangers of manure gas exposure and how to reduce risk to people and animals.
General safety preparations for manure agitation and pumping on farm are evacuate – extinguish – signage – ventilate.
EVACUATE: When stored manure is agitated or pumped from under the slatted floor of a barn, get everyone out of the barn, including animals if possible. Once people are evacuated, post signs and use barriers to reduce the risk of re-entry before it is safe. For outdoor manure storage areas, the only people around the area should be those moving the manure.
EXTINGUISH: Remove any potential ignition sources to guard against flash fires and explosions. Turn off power to any non-ventilation equipment and extinguish any pilot lights or other ignition sources.
SIGNAGE: Prior to beginning manure pumping and hauling, place warning signs at all entrances to buildings and storage areas where manure agitation is in progress. Make sure all on-farm family members and workers are aware of procedures, even those who may not be directly involved with manure removal. Ensure everyone understands what this activity means and the potential dangers so they respect and follow the signs.
VENTILATE: Monitor wind conditions, particularly wind inversions, when pumping from outdoor manure storages.
Further details from Dr. Cortus’s safety protocol discussion can be found on UMN Extension’s website.
Spring 2026 holds lots of potential for a successful crop and livestock year. Make sure manure nutrients are in the right place and manure is pumped and handled safely!
Content of this article courtesy of Melissa Wilson, wilso984@umn.edu and Chryseis Modderman, cmodderm@umn.edu , UMN Manure Management team, & Erin Cortus, ecortus@umn.edu, UMN Extension Ag Engineer. Diane DeWitte can be reached at stouf002@umn.edu.
Written for submission to The LAND - as March 2, 2026 Swine & U column
Last week, for a minute, it seemed like spring was here; then it rained, and the next morning we were shoveling a path to the barn. Never fear! March is around the corner, and with it an opportunity to get manure hauled out of the barns.
Maybe your manure plan involves fall application, but as the soils thaw and the tiles begin to run, it’s a good idea to review a few environmental protection habits which will help keep nutrients where they belong.
University of Minnesota Extension provides good resources for nutrient application calculation and groundwater and shoreland protection at its manure management website. Extension manure management specialist, Melissa Wilson, and manure management crops educator Chryseis Modderman provide the latest best management practices for manure application in our Land of Ten Thousand Lakes and Nine Million Pigs.
APPLICATION TIMING
The best time to apply manure is dependent on farm logistics, weather, soil conditions and a producer’s willingness to take risks. UM Extension recommends, when applying manure in the spring, producers wait until the snowmelt is complete and soils are thawed and drying. Springtime application will provide nutrients closer to the time growing crops will use them with a lower chance of nutrient loss. Conversely, if springtime soil conditions are poor, planting may be late after delayed manure application.Summer application is also an option. Dr. Wilson’s research has shown that directly applying liquid hog manure into growing corn can be successful; Injecting manure between the young rows provides maximum nutrient value, but specialized equipment is needed.
CALCULATING NUTRIENTS
Before planning for manure applications, consider how the nutrients will be managed for the upcoming crop. Will all the nitrogen (N) be supplied from manure? This will require a higher application rate and will overapply phosphorus (P) and potassium (K) for the crop year. If done too often, there could be environmental consequences when excess P enters waterways. Dr. Wilson, along with agronomy professors Dr. Fabian Fernandez and Dr. Dan Kaiser, have updated the UMN Extension Guidelines for Manure Application Rates to assist producers in correctly calculating manure application based on N or P needs of the crop or whether spreading liquid or solid manure. When using liquid swine manure, the chance of over-applying Phosphorus is critical to remember. These latest application rate guidelines based on N or P at this website.PATHOGEN MITIGATION
UMN Extension Crops educator Chryseis Modderman addresses the manure pathogen issue in this discussion of how to reduce common microorganisms in manure.Livestock manure is a valuable source of crop nutrients, but it can also come with pathogens that may cause livestock and people to become ill. The number and type of pathogens in manure vary based on animal species, feed, and animal health. There are many different types of pathogens in manure, so using multiple best management practices at once will give the best results.
Common bacteria found in livestock manure include Campylobacter, E.coli, Leptospira, Salmonella and Yersinia. Rotavirus is the most prevalent virus found in manure, and Cryptosporidium and Giardia are protozoa found in livestock manure and pet feces.
Modderman points out three main areas of focus where livestock producers can reduce pathogens:
In the animal: Stressed, unhealthy livestock are more likely to excrete pathogens than healthy animals. Therefore, keeping livestock healthy needs to be a priority to reduce the number of pathogens in manure. Just because an animal appears healthy, does not necessarily mean that their manure will be pathogen-free. Some animals are carriers of disease without ever showing symptoms, themselves.
Another way to decrease pathogens in manure is through feed selection. Adding antimicrobials to feed will reduce the number of pathogens in manure. Organic acids and yeast extracts added to feed have also been effective at lowering the number of pathogenic bacteria in manure. Replacing finely-ground feed with coarsely-ground feed can reduce Salmonella content in swine manure. Livestock producers should talk to their veterinarian before drastically changing feed.
During manure collection and storage: Using vegetative buffers near storage and areas of runoff will filter out pathogens before they reach a waterway. The effectiveness of a buffer strip depends on many factors, and the ideal buffer should be loam-textured soil for good infiltration planted with thick vegetation with deep fibrous roots. Buffers must be at least 15 feet wide (MN law requires 16.5 ft along ditches, and 50 ft along lakes, rivers, and streams) and are most effective during the growing season.
Storing manure under anaerobic (no oxygen) conditions, like deep pits below livestock housing, will also reduce pathogens. Though some bacteria can survive anaerobic conditions, most pathogens will be killed within 30 days. Using anaerobic digesters can accelerate the destruction of pathogens.
High temperatures combined with aeration also kills most pathogens. Composting is a good way to do this. A compost pile consists of organic material such as manure, bedding, and dead livestock. Temperatures within a compost pile can reach 150⁰F. We recommend two cycles of temperatures of at least 131⁰F to kill pathogens. Aeration and uniform heat distribution are mandatory for the breakdown of a compost pile into dark, soil-like material.
Lime added to manure can reduce pathogens and odors, and when it is land-applied, it also reduces soil acidification.
During land application of manure: The main concern with pathogens at application is runoff and loss through tile drainage. People are at the greatest risk for pathogen infection when manure runoff reaches resources like waterways or food crops.
Pathogen concentrations decrease when exposed to UV light and drying. Since that naturally occurs when manure is surface applied, delaying manure incorporation will reduce pathogen numbers. However, waiting to incorporate manure can have adverse environmental effects as nitrogen is lost to the atmosphere and runoff risk is increased. Flies and vermin are also more likely to pick up and carry pathogens from manure that is left on the surface. Therefore, the recommended method is to incorporate manure soon after application.
RUNOFF RISK ADVISORY FORECAST
The Minnesota Department of Agriculture (MDA) has teamed up with the National Weather Service to design a tool that helps farmers and commercial applicators determine the best time to apply manure. The Runoff Risk Advisory Forecast (RRAF) tool uses past and predicted National Weather Service weather data like precipitation, temperature, and snow melt.It predicts the likelihood that applied manure will run off fields in daily, next day, and 72-hour increments. Farmers and commercial applicators use an interactive map to locate their field and find the forecasted risk. MDA offers a ‘sign-up’ for Runoff Risk Alerts at this link: https://public.govdelivery.com/accounts/MNMDA/subscriber/new?qsp=MNMDA_3
Alerts will be sent via email or text when conditions are likely for a runoff event.
SAFETY ALWAYS
UMN Extension Ag Engineer, Dr. Erin Cortus, advises having a set of safety protocols on the farm prior to pumping manure pits. The UMASH farm safety checklist, https://z.umn.edu/UMASHmanurechecklist, is a terrific beginning to establishing standard operation procedures for manure handling.Dr. Cortus emphasizes that even though only a few folks from on or off the farm actually pump and haul the manure, it’s critical that everyone on-farm understands the dangers of manure gas exposure and how to reduce risk to people and animals.
General safety preparations for manure agitation and pumping on farm are evacuate – extinguish – signage – ventilate.
EVACUATE: When stored manure is agitated or pumped from under the slatted floor of a barn, get everyone out of the barn, including animals if possible. Once people are evacuated, post signs and use barriers to reduce the risk of re-entry before it is safe. For outdoor manure storage areas, the only people around the area should be those moving the manure.
EXTINGUISH: Remove any potential ignition sources to guard against flash fires and explosions. Turn off power to any non-ventilation equipment and extinguish any pilot lights or other ignition sources.
SIGNAGE: Prior to beginning manure pumping and hauling, place warning signs at all entrances to buildings and storage areas where manure agitation is in progress. Make sure all on-farm family members and workers are aware of procedures, even those who may not be directly involved with manure removal. Ensure everyone understands what this activity means and the potential dangers so they respect and follow the signs.
VENTILATE: Monitor wind conditions, particularly wind inversions, when pumping from outdoor manure storages.
Further details from Dr. Cortus’s safety protocol discussion can be found on UMN Extension’s website.
Spring 2026 holds lots of potential for a successful crop and livestock year. Make sure manure nutrients are in the right place and manure is pumped and handled safely!
Content of this article courtesy of Melissa Wilson, wilso984@umn.edu and Chryseis Modderman, cmodderm@umn.edu , UMN Manure Management team, & Erin Cortus, ecortus@umn.edu, UMN Extension Ag Engineer. Diane DeWitte can be reached at stouf002@umn.edu.
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