High value crops need high value inputs, particularly an adequate supply of fertilizer that can be applied when the crop needs it most.
More efficient use of fertilizer reduces input costs and significantly lowers both economic and environmental risks.
Solving some of these ongoing challenges has been a labor of love for USDA-ARS Soil Scientist Matias Vanotti since the mid-1990s. Though he has had some significant successes in removing ammonium from hog and poultry house waste, his latest breakthrough, he contends, can have a much bigger impact on the livestock industry worldwide.
Vanotti and his research team at the USDA-Agricultural Research Service (ARS) Coastal Plains Soil, Water, and Plant Research Center in Florence, S.C., developed a process of collecting ammonia from swine and poultry waste in membranes made from gas permeable polymers. The end product is high value liquid fertilizer with a high nitrogen content.
The membranes, which in a commercial setting will be placed under swine lagoons and poultry houses, have two cells.
One cell is filled with acid and the other with waste water from the livestock production facility.
The process extracts ammonia from the waste and mixes it with acids to form ammonia sulfate or nitrate, which can be used commercially as a source of liquid fertilizer for crops or other uses.
Vanotti and the USDA recently patented a new technology that uses these gas-permeable membranes to capture and recycle ammonia from swine and poultry wastewater.
The membranes, Vanotti contends, can be adapted to commercial scale.
These membranes are similar to materials already used in waterproof outdoor gear and biomedical devices that add oxygen and remove carbon dioxide from blood.
Process will work
“We have demonstrated in our lab work and on small scale tests on commercial swine and poultry farms that this process will work. Now, we are waiting for industry to take our results and convert this system into a product that will be available to farmers,” Vanotti says.
In a commercial application there are several benefits from using this type system, the USDA researcher says.
From an environmental standpoint, the ammonium trapped in this system is recovered before it escapes into the air.
Removing the ammonium from the air will help production facilities better comply with clean air standards.
Perhaps as importantly, it will make the working environment much better for farm workers, making it easier to find and keep a quality workforce in place.
“On the swine farms where we had systems of ammonia removal in place, the farmers noted a significant improvement in the workplace. And, it also provides a better environment for the animals being raised in confinement and likely will improve production,” Vanotti says.
In on-farm test with a hog producer, the ammonia removal system worked well enough to take 75 percent of the ammonium out of the air in the swine house. In this house, animal mortality dropped by 47 percent.
Decreasing mortality has a double benefit to poultry producers. The obvious advantage is producers have more birds to sell and make more efficient and profitable use of feed and other inputs used to produce the bird.
It also alleviates the need of disposing of dead birds, which can be a significant cost and a potential environmental risk.
Though animal performance was not documented in this series of on-farm testing, it is reasonable to assume that production would be increased, due to an improved environment inside the poultry house, Vanotti notes.
“In one of our on-farm tests, there was a mechanical problem with the system, and it quit working. The farmer recognized the problem almost immediately and called us. That was good indication that the ammonia removal system was valuable to the farmer, and when working properly, was a good indication that it was valuable to operations,” Vanotti says.
Vanotti points out that these impressive results came from using older technology based on biological ammonia removal treatment from liquid wastewater and re-using the clean water to flush the houses.
He says the new systems for ammonia removal from poultry and swine facilities could be has been much more efficient than the systems used in previous on-farm tests.
The new swine and poultry systems are slightly different, requiring the USDA to file for two different patents. However, Vanotti contends the swine and poultry systems are very similar and both have worked equally well in on-farm tests.
How successful these filtering systems work in large-scale livestock production remains to be seen, but in the lab they have been nothing short of spectacular.
In one study, Vanotti immersed the membrane into liquid manure that had 1,300 mg of ammonia per liter, and after 9 days, the total ammonia concentration decreased about 50 percent to 663 mg per liter — and as a result, the gaseous ammonia fraction in the liquid linked to ammonia emissions decreased 95 percent from 114.2 to 5.4 mg per liter.
He used the same process in 10 consecutive batches of raw swine manure and ended up recovering concentrated nitrogen in a clear solution that contained 53,000 mg of ammonia per liter.
Obtaining this level of ammonium extraction and nitrogen capture in a research lab is reason enough for farmers and livestock producers to take notice.
However, it’s the real world application that may make a significant improvement on their bottom line. If commercially adapted, this process would reduce the risk for grain farmers by reducing their fertilizer costs and making the supply more reliable.
In a swine operation with 4,000 to 5,000 animals, there would be about 30,000 pounds of nitrogen in the manure being lost in the air each year.
Capturing the N and processing it into a usable form of nitrogen fertilizer would be huge for both the livestock and row crop farmers in the animal rich, but grain poor Southeast.
The nutrient value of poultry litter is slightly different, but perhaps potentially even more important than swine waste in the Southeast, because of the size of the poultry industry across the region.
The potential fertilizer content of poultry manure varies significantly, depending on type of bird raised and content of the feeding ration.
However, the nutrients in this manure could adequately fertilize acres of corn and cotton grown in any of the Southeastern states.
Finding a new source of nitrogen would be big for row crop farmers in the Southeast. For example, a recent Virginia Tech study shows that N accounts for 57 percent ($102 per acre) of the total fertilizer cost of growing 150 bushel per acre corn in the state.
Vanotti says the technology is available and the price of materials for producing his system has actually gone down. Now, it’s up to industry to convert the USDA findings into an affordable and workable system for swine and poultry producers.
Companies wishing to learn more about the technology and the licensing procedure can contact: Jason Bray, Office of Technology Transfer, USDA, Agricultural Research Service (ARS), Athens, Ga., 30604-5677, phone 706-546-3496 or by e-mail at email@example.com.