Feedlots have come a long way in reducing harmful greenhouse gas emissions in recent years.
But a new federal research study has found that nitrogen losses in feedlots are still significant — and can significantly affect the bottom line.
“We’re losing about 50 per cent of the nitrogen to ammonia loss in a feedlot, and there are economic implications of that,” said Sean McGinn, a research scientist at the Lethbridge Research and Development Centre.
“Once you realize that 50 per cent of the nitrogen is lost to ammonia emission and that nutrient is then not available for crop growth, that can be recognized as real cost savings.”
McGinn and colleague Tom Flesch launched the two-year study as a way to track nitrogen emissions from feedlots, mainly in the form of ammonia.
“We know beef feedlots are ‘hot spots’ of ammonia emissions on the landscape, but we didn’t know as much about the dynamics of ammonia emissions from feedlots,” said McGinn.
“For example, we didn’t have real numbers from actual feedlots on how much is emitted, how much is deposited on nearby soil, and how much re-emission occurs when that happens.”
Using open-path lasers, a state-of-the-art measuring technique that is used in the oil and gas industry to measure emission concentrations, McGinn was able to show that “a large portion of the nitrogen fed as crude protein is volatilized from the feedlot’s cattle manure.” And about 14 per cent of the emitted ammonia was deposited on land adjacent to the feedlot.
“That 14 per cent is a large amount considering a typical feedlot emits one to two tonnes of ammonia per day,” said McGinn.
The implications of that are “enormous,” says a leading Canadian expert on mitigating greenhouse gas emissions from agriculture.
“Nitrogen is valuable,” said soil scientist Mario Tenuta, a researcher at the University of Manitoba. “Farmers pay for it in terms of fertilizers, and it would be wonderful to keep the nitrogen in the manure and not in the atmosphere.”
Tenuta was not involved in the research study, but said he believes it shows “solid evidence” about how much nitrogen is being lost from feedlots. From there, it’s much easier to “calculate the dollar value of that nitrogen.”
“It’s really a dollar value that’s lost, and somebody could potentially be making money off that dollar,” said Tenuta. “There’s an opportunity there for somebody to step in with an innovation and figure out how we could trap the nitrogen before it gets into the atmosphere and then get it back onto the land.”
The study also reinforces that feedlots — and producers — need to find ways to keep nitrogen out of the atmosphere, said Tenuta.
“How do we improve our manure handling or animal rearing to trap the nitrogen and keep the nitrogen from volatilizing?” he said.
“Do we have something that’s quick and easy right now? No. If it was quick and easy, it would be used at the moment.”
But there are practical steps that cattle feeders can take right now, added McGinn.
“There’s some simple things that can be done in terms of reducing the loss of ammonia, which I’m sure producers would like to see. There’s a cost to that loss,” he said.
First, reduce the amount of crude protein in the cattle ration.
“In feedlots, we see an increase in methane as crude protein increases, so reducing crude protein would be a big benefit,” said McGinn.
Next, incorporate manure into the land whenever possible.
“When manure is applied to land, if it’s at all possible to incorporate it, we could see a drastic reduction in ammonia loss,” said McGinn.
Next, feeders need to expand their composting programs, said Tenuta.
“A key thing will be to tie up the nitrogen with carbon material, like straw, to get it into an organic nitrogen form that can then be stabilized as a compost that could be hauled and applied to farmland,” said Tenuta, adding that feedlots are already composting, “which is fantastic.”
“Now we just need to continue along that line and try to trap more nitrogen as soon as it comes out of the animal and get it into an organic nitrogen form.”
And finally, if you farm near a feedlot, get your soil tested.
“If you’re a farmer close by to a feedlot, you need to consider that you’re going to get nitrogen input from the feedlot and then be careful not to apply too much nitrogen. You may not need to be applying as much,” said Tenuta.
“I would encourage those farmers to be relying on soil testing as a practical means to taking advantage of the nitrogen that’s been dropped in.”
These steps will help reduce some emissions, and save feeders some money in the process, but the real work in this area lies ahead, said Tenuta.
“There’s always going to be more work to be done in this area, unfortunately,” said Tenuta.
“The ultimate goal, somewhere down the line, is to go to zero emissions of direct and indirect greenhouse gases. We have lots of work and lots of innovation to do.”