Glacier FarmMedia – Major reductions in greenhouse gas emissions from fertilizer use are possible through 4R nutrient management, according to researchers from the University of Guelph.
But while the 4R concept is good (right source, right time, right rate and right placement), truly significant reductions lean heavily on achieving each factor simultaneously, said Claudia Wagner-Riddle, a professor of environmental sciences at the university.
For example, getting the right fertilizer on the right place is all well and good, but if the timing is poor, fertility is lost as emissions anyway, she said.
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“The kind of elephant in the room is, eventually, we do need to work on the right rate. That’s the toughest nut to crack,” she said. “You don’t want to be standing in the middle season saying, ‘Oh, I should have applied more.’
“In this area there is some (beneficial) application technology, but the other big part is that forecast of what the season is going to be like, what supply from the soil will be available and what the plants need… We can do that based on historical data, but what farmers are looking for is in this season.”
The solution is to monitor what the soil is providing alongside crop needs. It is critical to understand how nutrients are lost (via water and as ammonia for nitrogen) and what conditions are conducive to that loss.
Combined with on-farm experimentation, growers can determine whether the expense of repeatedly erring on the side of caution by applying extra fertilizer is offset by the occasional yield boost, said Wagner-Riddle.
“Losses subtract from what you apply and make the whole thing less efficient,” she said, adding farmer-led research groups in the U.S. have been able to demonstrate emissions reductions by better balancing nitrogen inputs with what’s derived at season’s end.
Modelling developed through her research suggests emissions reductions nearing 50 per cent could be achieved without negative yield impact.
Both carrot and stick incentives — in addition to continued education efforts — will be important to meet emission reduction targets, said Alfons Weersink, one of Wagner-Riddle’s research colleagues and a professor of agricultural economics.
However, the nature of the proverbial carrots and sticks is up for debate.
“A tax on fertilizer has been used in some countries and American states, but it’s not necessarily that effective because there are not a lot of substitutes,” said Weersink.
A system where taxes on fertilizer are used to support further incentives and outreach programs, might have more impact, he added.
Cost-share programs or subsidies for precision fertility equipment could also promote 4R management, though such an approach does not inherently mean less fertilizer will be used since application rates often shift from uniform coverage to more concentrated application in specific areas.
“Really you just try to educate people on the effects of fertilizer. Higher prices will make people more cognizant of what they’re applying,” said Weersink.
“When erosion was a big issue in the 1970s and 1980s, new technology and strategies helped reduce the environmental impact, but was also profitable for farmers to use it… It’s harder to see fertilizer loss to air and water.”
Slow-release inhibitors designed to allow greater crop nutrient absorption are an example of a technology that could help achieve emission reduction goals.
The combination of new technologies and increased 4R adoption is a practical and effective path forward, said Clyde Graham, executive vice-president of Fertilizer Canada.
Other strategies such as sub-surface banding and a greater focus on micronutrient deficiencies could go further.
In an ideal world, policies aimed at reducing fertilizer-based emissions would be based on incentives, said Graham.
“Where the growers are being encouraged rather than forced, that we think will have the best uptake,” he said.
“We would like to see a healthy debate around this issue, but I think the best way to achieve better climate outcomes is for farmers, companies, environmental organizations and governments to work together.”
Matt McIntosh is a contributor for Glacier FarmMedia. His article was originally published in the Nov. 29, 2021 issue of Farmtario.
