Managing manure during winter months
Whenever possible, winter application of manure should be avoided to prevent contamination during spring run-off.
Manure management is an important aspect of any livestock operation. Producers need to be aware of the environmental implications of storing manure and applying manure to cropland. When applied at proper rates, manure is a valuable asset to crop producers. Manure contains nutrients essential to plant growth and increases the organic matter of the soil. It aids in water retention, lessens the impact of wind and water erosion, and promotes growth of beneficial organisms in the soil. However, over application of manure above the nutrient needs of the crop can result in potential environmental risks from leaching or run-off into water. Other factors such as method and time of application, rainfall, and soil texture also impact the potential for environmental damage.
There are several methods of manure application. Broadcasting the manure onto the field has long been the traditional method and is used in all seasons of the year with all types of manure. Producers who have liquid manure collection systems can inject the manure directly into the soil. The advantage to this is that it virtually eliminates the odors and volatilization of nitrogen associated with manure application. The disadvantage is that injection is not possible during winter months. Time of application is critical when applying manure to cropland. Fall application of manure allows more time for the organic portion of the manure to breakdown and become available for plant use the following spring. However, it also allows more time for nitrogen and phosphorus to be lost to the environment. Spring application of manure allows the least amount of time for environmental losses.
Many dairy operations in Minnesota are faced with a challenge each year regarding manure management during the winter months. For many producers, winter application of manure is unavoidable due to lack of a storage system. And because of the inability to immediately incorporate the manure into the soil, the manure remains on top during the entire winter season where it is susceptible to run-off and wind erosion. Therefore, whenever possible, manure application during winter months should not be considered as part of a routine manure management plan. If manure must be applied during the winter months, plan ahead to select the fields most appropriate for winter manure application. Choose a field that is level and avoid fields with steep slopes and those that are near waters of the state. Test the manure before application and apply at conservative rates to minimize nutrient loss to erosion. Surface residue cover will help prevent nutrient movement during the winter months but may delay contact with the soil in the spring. Tillage along the contour, rather than up and down slopes, is important to hold the runoff between tillage furrows. Be sure to follow MPCA setbacks for winter application of manure. The minimum setback to most waters of the state is 300 feet on frozen or snow-covered ground. Livestock operations designated at a Concentrated Animal Feeding Operation (CAFO) are subject to guidelines set by the EPA and are not permitted to apply manure during winter months.
Winter feeding location is very important. It is the responsibility of the producer to make sure that they locate and manage the winter feeding facility so that the manure-contaminated runoff from the site does not discharge into waters of the state. There are a number of Best Management Practices that will reduce the potential for an environmental hazard from manure accumulated in livestock winter feeding facilities. Choosing a suitable location for the winter feeding site is the most critical aspect of managing the manure from a supplemental feeding facility. Avoid locating the winter feeding area near environmentally sensitive areas such as lakes or streams, near sinkholes, shoreland, or private wells used for drinking water.
Another major manure management concern during the winter months is the accumulation of manure packs. Management practices that minimize the formation of manure packs are encouraged. One management technique that prevents the accumulation of manure packs is to frequently move the location of the feeding equipment throughout the available area. By rotating the feeding equipment, concentration of nutrients in a manure pack can be avoided. The number of animals in the winter feeding facility will determine how frequently the equipment must be moved to prevent manure pack formation. The higher the density of animals, the more frequently the feeding equipment should be moved. If it is necessary to allow a manure pack to form, be sure to follow MPCA guidelines governing acceptable location of manure packs.
Manure management from livestock wintering facilities in Minnesota may continue to be a difficult situation for many dairy producers. Whenever the ground is frozen, runoff potential will increase and producers must take care to prevent environmental contamination from their wintering facilities. Use of Best Management Practices will reduce the environmental impact of outdoor wintering facilities.
For more information about manure management, visit the University of Minnesota Manure Management and Air Quality website, the Dairy Extension manure section, or the Minnesota Pollution Control Agency website.
Published in Dairy Star January 14, 2006