As winter approaches, the challenges associated with the application of cattle manure become more pronounced. Adopting best practices that maximize nutrient utilization and safeguard our water resources is crucial. Daniel Andersen, associate professor of agricultural and biosystems engineering and extension ag engineering specialist at Iowa State University, offers some critical considerations for beef manure application in the winter.
Compliance with regulations
"Familiarize yourself with and adhere to local regulations governing winter manure application," he said. "Iowa prohibits liquid manure application from confinement operations with more than 500 animal units on snow-covered ground from Dec. 21 to April 1 and frozen ground from Feb. 1 to April 1."
While solid manure application is not prohibited by Iowa law, careful consideration should be given to minimizing negative impacts on water quality as the state's waters are protected.
"For a cattle operation, this means that how the law impacts you is dependent on your operation and the manure management system you use. The law doesn't prohibit manure application if you work with solid manure, like a bedded pack," Andersen said. "However, all manure applications must prevent water quality violations. Applying from a deep pit or other liquid or slurry manure system will be restricted if you use a deep pit or other liquid or slurry manure system."
If your facility has an NPDES permit or an NRCS Comprehensive nutrient management plan, be sure to check restrictions specific to your operation in these documents. Typically, both will prohibit winter manure application for all types of manure, both solid and liquid.
The "winter manure application" rules have two parts: a date and condition. Both components must be true for liquid and slurry manure application to be prohibited. So, while the calendar date of Dec. 21 is quickly approaching, it is unlikely that the ground will be snow-covered (defined as 1 inch of snow or 0.5 inches of ice on the soil surface). As a result, liquid manure application would still be allowed until snow cover occurs.
Understanding snow conditions
Applying manure directly onto snow-covered fields poses a significant risk of nutrient runoff when the snow melts, especially if melt will occur quickly. Instead, wait to apply until after snowmelt or choose alternative manure management strategies. Applying manure on frozen ground is also discouraged, as the frozen surface inhibits absorption, increasing runoff potential.
"Timing is key; apply manure when limited snow is present and quick melts aren't expected," he said. "Slow melting encourages water infiltration and absorption of manure nutrients into the soil."
If applying solid manure when snow is present is necessary, choose fields with lesser snow accumulation that are relatively flat. Increase buffer or setback distances around field edges to reduce the risk of nutrient transport from the field.
Source: iastate.edu
Photo Credit: usda
Categories: Iowa, Livestock, Beef Cattle