Proper management of livestock manure is a top of mind concern for livestock managers, especially those involved with dairy and feedlot operations. Proper management techniques are designed to help protect surface and groundwater quality while also reducing odors associated with confined animal feeding operations (CAFOs).
The Environmental Protection Agency (EPA) defines an animal feeding operation as a farm or feedlot where animals are kept and raised in confined areas for at least 45 days over a 12-month period.
Regulations vary depending on where farmers operate. Typically, states regulate manure through the National Pollution Discharge Elimination System. It requires animal feeding operations of certain sizes to keep records on manure, create nutrient management plans (NMP) and to handle manure under strict regulation.
Because dairies and cattle feeding operations, by the nature of their businesses, keep large numbers of animals, it is important for operators to develop and follow an effective NMP.
Deanne Meyer, PhD, a livestock waste management specialist in the Department of Animal Science at the University of California-Davis, told WLJ, “When developing a plan, producers should identify specific goals and carefully evaluate options to achieve those goals.”
University of Nebraska Extension’s Leslie Johnson, Project Manager for the Animal Manure Management (AMM) team, said, “The plan should be reviewed on a regular basis to ensure it is being properly used.” However some producers will write a nutrient management plan so they can get a permit and put it in a filing cabinet and forget about it.
NMPs typically outline how manure is stored, where it will be applied (as fertilizer) and at what rate it will be applied, explained Johnson. “Most plans don’t set a specific rate, but state it will be used agronomically, which means you’re going to apply it at a rate that will allow for the crops to use the nutrients.”
Although there are different storage methods used across the country, three popular storage structures include solid manure storage, run-off holding ponds, and anaerobic treatment lagoons.
In a feedlot situation, the majority of the manure that is taken out is in solid form that would be scraped and piled. “Sometimes it’s piled right on the operation near where it was gathered so any run-off can go directly into the holding ponds, or it is piled in a field based on calculated amounts appropriate for that particular field,” Johnson told WLJ. The manure will later be spread throughout the field.
When piled for storage, Meyer said good management practices say it should be stored on an impermeable surface, “but the challenge is, as defined by whom?” Sources to help identify the definition include the Natural Resources Conservation Service (NRCS) and the American Society of Biological Engineers.
Run-off holding ponds allow water that runs off the feedlots to go into containment ponds where it is allowed to settle. After a settling period, water is commonly pumped off the top of the pond where there aren’t a lot of solids and pumped onto fields through sprinkler irrigation or applied to fields using a tractor and tank or a drag hose that pumps the liquid directly from the pond to the tractor to be injected into soil.
Open air holding ponds—unless oxygen is added—will be anaerobic, Meyer explained. Anaerobic lagoons are earthen structures, which look at first glance like farm ponds. They are designed to provide biological treatment and long-term storage of animal waste and are generally larger than manure storage basins, which do not provide significant biological treatment or long-term storage.
“Anaerobic lagoons will help reduce the total solids, Meyer said, “but is not necessarily a valuable nutrient management tool as it does nothing for phosphorous or salt levels. And, depending on the species of the manure, it may or may not increase the amount of plant-available nitrogen.” She stressed “may” because the quality of the manure will depend on how the herd is managed.
Application of manure to crops should be based on crop nutrient needs. Meyer said managers should have a good plan that includes soil and nutrient analysis to identify when in the growing season the crop will need nutrients. This an area where good record keeping comes into play. Meyer said producers and managers need to be able to document what they have done and when it was applied.
“Being able to distribute both the nutrients and the water as uniformly as possible under whatever management system is being used is what folks want to strive for—that’s the objective,” Meyer told WLJ.
Challenges in documentation can include nonspecific measuring devices and sampling. “Quantifying how much material was land-applied can take some effort,” she said. “For example, when measuring by loader bucket, the amount varies. Sometimes estimates are as good as we can get based on data collected.”
With all types of manure storage, the NMP includes emergency plans in case something unexpected happens such as a leak or spill. Johnson said this plan should include a list of contacts to assist with cleanup and outline what needs to be done to help prevent manure from getting into water.
“The biggest thing livestock producers can do to reduce their risk is to keep very, very good records,” Johnson said. Using Nebraska as an example, she said records need to be kept on lagoon levels and checked after every rainfall so operators know if it has gone up. Beyond that, lagoons should be checked at least monthly. “If the level is going down too quickly, you know you’ve developed a leak and need to take care of it. But, if you’ve kept good records that show you’re doing your very best, you’re going to be in a lot better shape than if you say you checked the levels but didn’t write it down.”
Adding to the idea of good record keeping, Meyer said, “Having a good NMP is like having a budget. You have to know what is needed, and if it went where it was supposed to go. In nutrient management you have what you plan on doing, and then you need to look at what you did to make sure you followed through. You don’t just need a plan on a shelf that nobody is following.”
In Nebraska, ongoing training is required every five years to maintain the permit. While state law only requires one person per operation to attend, Johnson recommends anyone involved with manure management to attend the training. “It’s important they all know what’s required and what they should be doing properly.”
Training on nutrient management varies throughout the country depending on state regulations. Many resources and training opportunities are available through various university extensions and other sources.
Johnson concluded, “NMPs need to meet regulations put in place by EPA through the Clean Water Act and state regulatory agencies are responsible for making sure that happens. Some states interpret it differently, but the general rule is the same— keep manure out of the water.”
WLJ attempted to reach dairy and feedlot operators for input on this story, but was unable to obtain comments as of press time. —— Rae Price, WLJ Editor