Over the past several years, manure application to farm fields has come under additional scrutiny, particularly the applications of manure to frozen and/or snow covered ground. Livestock producers and custom manure applicators should always exert extreme caution, follow best management practices (BMP) and utilize best available technologies (BAT) when applying manure, particularly when field conditions are less than ideal, which would definitely include winter-time application. The top priority of any application of nutrients to the land should be to protect water quality.
No matter the size of a livestock, dairy, or poultry facility and if it is an animal feeding operation (AFO), it may be designated a CAFO, if after being inspected by a permitting authority, it is found to be adding pollutants to surface waters. It is also important to note that the US EPA permit will cover both the production and land application areas.
These types of situations could be avoided by following standards established by the United States Department of Agriculture's (USDA) Natural Resources Conservation Service (NRCS) in its Waste Utilization Practice Standard (#633), which may be accessed by logging onto http://www.ohleap.org/FactSheets/index.html.
By adopting and following this respective USDA-NRCS Practice Standard, livestock farmers and custom manure applicators can significantly reduce the risk of pollution problems, but they should keep in mind that with fluctuating weather conditions, application of manure can still be risky and pose a threat to water quality.
Application of manure to frozen or snow covered ground is not recommended unless it becomes necessary due to extreme situations. Such situations typically arise from a lack of storage capacity (a minimum of six months capacity is recommended; one year is ideal). If manure application becomes necessary on frozen or snow-covered soils, only limited quantities of manure should be applied to address storage limitations until non-frozen soils become available.
If wintertime application becomes necessary, applications are to be made only if ALL of the following criteria are met:
- Application rate is limited to 10 wet tons/acre for solid manure more than 50% moisture and 5 wet ton/acre for manure less than 50% moisture. For liquid manure, the application rate is limited to 5,000 gallons/acre.
- Applications are to be made on land with at least 90% surface residue cover (e.g. good quality hay or pasture field, all corn grain residues remaining after harvest, or all wheat residue cover remaining after harvest).
- Increase the application setback distance to 200 feet "minimum" from all grassed waterways, surface drainage ditches, streams, surface inlets, and water bodies. This distance may need to be further increased due to local conditions (e.g., higher slopes, or sensitive or high quality streams in the area).
- The rate of application shall not exceed the rates specified in Table 4 of USDA/NRCS Practice Standard 633 - Determining The Most Limiting Manure Application Rates for winter application.
- Additional winter application criteria for fields with significant slopes more than 6% include manure shall be applied in alternating strips 60 to 200 feet wide generally on the contour, or in the case of contour strips, on the alternating strips.
Livestock farmers and custom manure applicators need to note that USDA-NRCS Practice Standard 633 allows for winter manure application; however, it is not recommended, particularly for operations that produce significant volumes of manure. A manure management plan should not include routine winter application. If winter application is unavoidable because of extenuating circumstances, only apply enough to address storage limitations until non-frozen soils are available.