Manure handling

MINNEAPOLIS — Fall is when many dairy farmers agitate and land apply stored manure and milking center wastewater. Many farmers try to complete manure agitation and land application as quickly as possible and make the best use of valuable manure nutrients. There are numerous things to consider before and during stored manure agitation and land application to accomplish these tasks in a safe and environmentally sound manner.

Manure is stored in earthen lined basins, above ground tanks or below ground pits either beside the barn or under the barn. This year stored manure agitation and land application may be a bit different for some farmers with uncovered manure storage structures. These uncovered manure storages may have more water in them because of the above normal rainfall we had this year. Annual precipitation, storm events and freeboard between the top of the manure and the top of the manure storage are considered when sizing uncovered manure storages. In Minnesota manure storages are designed to hold 24 to 26 inches of precipitation and five inches of rain from a 25-year, 24-hour storm. Several Minnesota storms had rainfall events that dropped over 5 inches of rain. So depending on location, some farms will have more material in their uncovered manure storages this fall. This may mean that it will take more time to agitate and land apply the manure. Nutrient levels may also be down slightly this year because of dilution.

Check weather forecasts for predictions of precipitation when planning manure application to avoid land applying manure prior to a large or intense rainfall event. Large or intense rains can lead to surface runoff over fields or down open tile inlets which carry away valuable crop nutrients in manure and contribute to surface water pollution. The National Weather Service offers a new activity planner forecast for the upcoming seven days. This tool and other weather forecasts can help you avoid land applying manure prior to rainfall events.

To agitate and land apply manure quickly in an environmentally sound manner it is good practice to:

• Check equipment thoroughly for broken hoses, loose connections or leaky valves or gaskets.
• Review land application plans and the location of sensitive features including streams, lakes, wet lands, sinkholes and open tile inlets.
• Layout a plan to collect a composite manure sampling after agitation for lab analysis. Consider sampling at different times and locations during agitation and land application. Keep collected manure cool if collecting during warm weather and freeze samples to be submitted until shipped. Follow instructions from the laboratory.
• Be prepared for a manure spill. Planning and forethought may help reduce the environmental impact of a manure spill.

Both environmental safety and human safety are important during manure agitation and land application. All manure storage facilities present safety risks that need to be recognized and managed. Here is a list of hazards and safety risks associated with stored manure agitation and land application.

• Stored manure can be a source of potentially harmful or fatal gas emissions during agitation. Ammonia, hydrogen sulfide and methane gases can accumulate in stored manure and be released during agitation. Open air manure storages can also generate localized layers of hazardous gases in low areas when there is little to no breeze. Avoid standing downwind of the agitators during agitation. Barns with pits need to be ventilated at summer time ventilating rates when agitating manure pits. Remove animals if possible. Keep people out of the building and put lockout tags on all doors during agitation.
• Do not enter manure pits without self-contained breathing equipment, a safety harness and sufficient support to remove a person if they become overcome. Fatal gases can collect in manure pits. Multiple tragic deaths can occur when a person who has entered the pit is overcome and a second person goes into the pit to help and is overcome too.
• Manure coated surfaces are slippery. The sides of earthen lined basins can be steep and uneven. People and equipment can fall into pits, tanks and basins.

Agitation and land application is an important job of many animal operations. Producers need to consider many things to accomplish these tasks in a safe manner that uses nutrients to best advantage.

Source— Kevin A. Janni, University of Minnesota Extension