Bouncing through a durum wheat field south of Regina on an all-terrain vehicle, with a shovel strapped to the vehicle’s back and an iPad mounted on its front, Tyler Kessler is taking soil samples and collecting moisture data.
Kessler is an agronomist and spends his days advising farmers on the best way to apply fertilizer to help their crops reach their yield potential.
More fertilizer doesn’t always mean a bigger crop, he says, if there isn’t the right mix of rain, sunshine and soil conditions. And too much fertilizer can simply be wasted, with the unabsorbed nitrogen transformed into nitrous oxide (N2O) that’s released into the atmosphere.
“We’re not applying nitrogen where we don’t need it — that’s a huge environmental benefit,” Kessler said.
Increasingly, farmers are adopting more sophisticated fertilizer products and application methods in order to grow the most food, while spending the least amount of money. At the same time, these new approaches can reduce emissions of N2O, a greenhouse gas that is 300 times more potent than carbon dioxide.
So what’s good for the pocketbooks can also be good for the environment.
“When farmers are making economical decisions based on data and precision agriculture, the environment wins every time,” Kessler said.
The new farming frontier
A dramatic increase in manufactured fertilizer use in recent years — up 150 per cent in Western Canada since the 1980s — has meant a huge jump in both crop yields and emissions of nitrous oxide, according to Agriculture and Agri-Food Canada.
Most nitrous oxide, commonly known as laughing gas, emitted into the atmosphere is generated naturally through a microbial process in the soil. However, farms end up emitting more nitrous oxide when commercial fertilizer exceeds crop demand, usually due to timing, rainfall or soil conditions, and some excess fertilizer converts to N2O.
Fertilizer use on Canadian farms is responsible for so much nitrous oxide that it accounted for nearly one-quarter of total agricultural emissions in 2017 — the equivalent of driving 2.7 million cars for a year.
“The simplistic thing is [to] reduce fertilizer applications, but that fails to take into consideration what happens to crop yields,” said Richard Farrell, an associate professor at the University of Saskatchewan who studies soil science. “We don’t want to reduce yield, we want to maintain yields but reduce emissions.”
Farrell is currently studying how the timing of certain fertilizer products can reduce N2O emissions.
Research has revealed a spike in nitrous oxide emissions after the spring thaw, said Farrell, when moisture from snow mixes with residue nitrogen in a “perfect storm for nitrous oxide.” That means farmers who apply fertilizer in the fall are most at risk of losing fertilizer to the atmosphere, he said.
Another burst of N2O release can take place if rainfall occurs soon after fertilizer is applied in the spring, specifically if the growing plant hasn’t had enough time to absorb the nitrogen.
According to Farrell, for every 100 kilograms of fertilizer that’s applied, about one kilogram (or one per cent) becomes nitrous oxide. The percentage may seem low, he says, but given how much fertilizer is applied to Canada’s millions of acres of farmland, the impact is “significant.”
Fertilizers are evolving
Research is just beginning to emerge that suggests farmers can use less fertilizer if they use enhanced products.
Farrell said he hopes the higher-priced enhanced efficiency fertilizers already on the market will reduce the farming community’s nitrous oxide emissions — if they’re widely adopted.
These include slow-release urea fertilizers, which have a protective coating to control the nitrogen release, giving the plant more time to absorb it. Nitrification and urease inhibitors also help stop the eventual conversion to gas.
And other so-called “smart fertilizers,” largely still under development, have a coating that reacts to plant signals, only releasing nitrogen when the plant needs it.
But Farrell is blunt about the fact farmers must be convinced there is an economic benefit to buying premium products. “We don’t pay farmers to protect the environment. We pay farmers to produce food,” he said.
The numbers seem to be on his side; according to Statistics Canada’s quarterly Farm Input Price Index, nitrogen-based fertilizer prices rose roughly 13 per cent per year between 2000 and 2007.
Turning to tech
As for Kessler, he’s banking on technology being the driver of change for farmers, including new software, satellite imagery, moisture probes and sensors that measure electrical conductivity in soil — all aimed at precisely calculating fertilizer needs.
In assessing an 160-acre field in the spring, Kessler used modelling software from CropPro Consulting to map different zones. While the ground appeared flat, the software showed it actually had varying topography, with different soil structures, salinity and moisture.
Kessler then wrote a prescription of sorts for the farm’s equipment, feeding instructions and GPS coordinates to the tractor and seeder. It uses something known as variable rate technology to outline what kind of fertilizer to apply and how much for each zone.
The machines could then automatically adjust what was plugged into the ground next to the seed, rather than blanketing fertilizer on top of the surface, as was done historically.
The 5th ‘R’
Kessler subscribes to what he calls the “4R method of fertilizing” — using the right source of nutrients, applied at the right rate, at the right time, in the right place.
Jocelyn Velestuk, another agronomist who farms 3,000 acres with her husband near Broadview, Sask., would add an additional “R” to the list: “Right balance.”
Like most farmers, Velestuk uses crop rotation to add nutrients to her soil naturally. That means she’ll plant a legume, such as lentil or chickpea, after a cereal or oil crop as a way to add organic fertilizer to the soil, so she doesn’t have to apply synthetic fertilizer to the land.
Velestuk is part of a “regenerative agriculture” movement that tries to reduce input costs — namely fertilizer, chemicals and fuel — while maintaining profit-per-acre.
Beyond crop rotation, she also experiments with cover crops (a crop grown to protect or enrich soil, often over the winter, that also removes excess nitrogen) and intercropping (growing two crops together to add different organic nutrients into her soil, and to break weed and bug cycles).
Even with those methods, her farm still spends more than six figures on manufactured fertilizer every year. So Velestuk takes soil samples and uses a software-modelling program to figure out the most efficient way to apply that fertilizer on a field-by-field basis.
“We want to make sure we get that fertilizer to the plant. It is no good to us if we’ve paid for fertilizer that’s in the atmosphere,” Velestuk said.
“You can really get more efficient with your fertilizer. And yes, you can find that sweet spot where you are decreasing the greenhouse gas emissions, as well as being efficient getting the fertilizer right to the plant,” she said. “It’s win-win.”
From CO2 to N2O
Velestuk, also president of the Saskatchewan Soil Conservation Association, proudly touts the Prairie farming community’s track record when it comes to sequestering another gas: carbon dioxide.
Since the 1980s, farmers in Western Canada have embraced low-till farming methods — like seeding directly into last year’s crop stubble, which reduces soil disruption and increases how much carbon dioxide is absorbed into the soil.
Currently, Prairie farmers sequester more CO2 than they emit. But any increase in nitrous oxide emissions threatens to undermine that achievement.
While both Velestuk and Kessler believe emerging research, products and technology will allow farmers to use consistently fertilize more efficiently, they also say governments and universities need to focus more attention and resources on fertilizer management.
“We’re just on the cusp,” Kessler said. “Growers care about the environment, they care about their soil and their land. I think they care about it more than anybody.”Autor(a): Fonte: