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Fertilize the crop, not the atmosphere

Keeping nitrogen in the soil means higher crop yields, plus reducing greenhouse gases that are more potent than CO2

Fertilize the crop, not the atmosphere
Reading Time: 4 minutes

There’s a lot of interesting science about how nitrogen behaves in the soil. If you have a techie disposition, you’ll enjoy learning about how different forms of nitrogen (ammonium and nitrate) have positive or negative charges and how that leads to specific interactions with soil — which has a negative charge, by the way — and how that interaction affects the level of plant-available nitrogen and how N stabilizers can influence this whole underground relationship .

Or maybe you’re not a techie — you just want to know if nitrogen stabilizers actually do what they say on the label: increase crop yields by decreasing nitrogen loss.

Lorne Thoen, product manager with Dow AgroSciences, encourages farmers to take a hard look at the science behind nitrogen stabilizers, do some math, and think about the overall cost of nitrogen loss — because it’s not just a yield issue, it’s an environmental one, too.

<strong>Applied vs. available</strong>

“I understand that people can be skeptical when it comes to this,” Thoen says. “But nitrogen is one of the biggest investments you make on the farm, and when you lose it to denitrification or leaching, it’s costing you real money.”

Nitrogen applied is not the same as nitrogen available, that’s a given. But it’s important to know there is a lot of microbial activity going on underground that can destabilize available N, putting it at risk of being carried away before your crop can use it.

“Making sure your nitrogen stays in the root zone is one of the most important things you can do for your crop,” says Thoen, explaining that nitrogen stabilizers like N-Serve and eNtrench, do that by inhibiting the activity of specific soil bacteria that convert ammonium into nitrate.

While both are plant-available forms of N, ammonium carries a positive charge while nitrate carries a negative one. Soil is negatively charged and, remembering your high school chemistry lesson about how opposites attract, that bodes ill for nitrate. Its negative charge means it can’t bond with the soil, so if not taken up by the plant right away, it will leach away or denitrify into the atmosphere. Ammonium, with its positive charge, bonds strongly with the soil until it’s converted to nitrate.

Thoen points out that N-Serve and eNtrench don’t stop the conversion of ammonium to nitrate, they simply slow the process in order to hold N in its ammonium form in the soil for longer (up to 10 weeks) so that when your plant needs it, it’s there. “The time these products protect nitrogen the most is when we have warm, moist soil, which is when those soil bacteria are most active, and also when your crop has the highest yield potential,” he says.

Indeed, over 35 years of research trials across North America has shown that these two products can, on average, reduce nitrogen leaching by 16 per cent and denitrification by 51 per cent. Research trials conducted over the last three years have shown that using N-Serve and eNtrench results in, on average, 21 per cent more nitrogen available to the crop.

Which is interesting, says Thoen, given that in a recent survey of farmers in Western Canada, respondents estimated their nitrogen losses to be no more than 10 per cent. “A lot of people think that 10 per cent is OK, that it’s an acceptable loss,” he says. “But if you applied that to any other business — if you had a 10 per cent leak in your widget factory, everyone would be saying ‘fix that leak!’”

<strong>It’s all about yield</strong>

“The only difference between N-Serve and eNtrench is that their formulations are meant to be used with different fertilizer sources,” says Thoen. The latter is meant to be used with liquid fertilizer or liquid manure and is simply mixed into the tank before application, while N-Serve is for use with anhydrous and requires a specialized pump to deliver it safely into the nurse tank. “Down the road, we hope to get eNtrench impregnated onto urea, but I emphasize, that’s still down the road.”

Both products are priced the same at just under $12 per acre, and Thoen encourages growers to do the math before deciding that’s too big an add-on to the fertilizer bill.

In field-scale trials conducted in Western Canada, Dow’s nitrogen stabilizers increased canola yields by 8.1 per cent and wheat by 5.8 per cent. So if you had a target canola yield of 45 bu./ac., for example, you’d be looking for yields to increase to something like 48 bu./ac. by using one of these products. As of December 2017, canola futures were hovering around $11.50 per bushel, so that would be a $34.50 return per acre — not bad on a $12 per acre investment.

<strong>Stewarding the land and air</strong>

“Nitrous oxide is a significantly more harmful greenhouse gas than CO2,” says Thoen.

It’s no small consideration. There is a lot of scrutiny on the environmental impacts of agriculture — both as a greenhouse gas emitter and steward of water sources. Keeping nitrogen from gassing off into the air as nitrous oxide is really the low-hanging fruit when it comes to reducing emissions — remember that 51 per cent reduction in greenhouse gases that N-Serve and eNtrench have demonstrated.

Similarly, the 16 per cent reduction in leaching helps to keep nitrogen phosphate out of water sources. Thoen says that in the U.S. Corn Belt, where nitrogen application tends to be high, groundwater contamination became a big issue, particularly after increased oil and gas activity added to the environmental load. Eventually, regulations were put in place to limit the amount of fertilizer runoff into water sources and growers there turned to N-Serve and eNtrench to help them meet those goals. That may have been the initial impetus for some to use the products, he says, but increased corn yields sealed the deal for them.

To Thoen, it’s a win-win: farmers have a product that not only demonstrably boosts yields, but that also provides a proven environmental benefit. “If you use these products, you’re doing the right thing for the land, and you’re maximizing nitrogen use, and you’re increasing yields,” he says.

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