There is no silver bullet in terms of finding manure management and environmental solutions for pork operations. But Jeff Lorimor, Iowa State University agricultural and biosystems engineer, and his fellow researchers are working to provide new tools that producers can use alone or in combination.
With the U.S. Environmental Protection Agency's new concentrated animal feeding operations rules, more pork producers will need to apply for appropriate permits. A bright spot in the new rules is the opportunity to establish what are called "voluntary alternative performance standards based on innovative technologies," says Lorimor.
He is researching an infiltration-wetland system, that "captures feedlot runoff and forces it to infiltrate into the soil, thereby removing many of the contaminants. Tile lines under the infiltration basin collect the infiltrated water and what remains of the pollutants and carries them to a wetland."
The wetland further cleans the water before it moves through a grass waterway to the stream. "The waterway cleans the flow even more than the wetland," Lorimor adds. "In five years of research, we've proven that the system reduces contaminant concentrations and flow volume, providing better overall water-quality protection than total containment."
Lorimor is directing another project that tests and demonstrates the effectiveness of vegetative filter strips. "We measure and sample flow above and below grassed areas beyond the feedlots. We’ll use the data to calibrate a filter-strip model," he notes. "Once the models are ready, we can do site-specific comparisons and predict water-protection effectiveness."
A similar modeling project is helping determine the effectiveness of containment basins around open feedlots. "We can predict how much overflow occurs each year at six different sites in Iowa for each of five systems," he says.
The model shows that total containment isn't really total containment. "We can control most of the runoff from open lots by capturing it and holding it for land application. But the containment can overflow because of chronic rainfall and lack of acceptable pumping days. If a containment enters the winter almost full, it overflows before enough drying days occur in the spring to pump it down," says Lorimor.
If DNR and EPA officials approve the two models, producers will be able to use them to select a system that will be the most effective for their specific operations.
These alternative technologies should save producers money. "Total containment comes in at about $50 to $100 per head. The alternative technologies will cost significantly less," Lorimor says. "Another advantage is those technologies are more passive, meaning they don't have to be pumped to prevent overflow."
The alternative technologies will still require attentive management to be effective. "Vegetative filter strips must be maintained so they don't channel. Wetlands have to be sealed. Infiltration systems only work on certain soils. These alternative technologies also will make a larger footprint on the ground than a containment basin," he notes.
The next steps are to recruit additional feedlots as demonstration sites and complete the two models. Then state and federal regulators will decide if producers can use these alternative technologies to comply with EPA’s new CAFO rules.
Iowa State University