Paying more attention to nitrous oxide emissions


Nitrous oxide is one of the three main greenhouse gases emitted by agricultural activities, and nitrogen fertilizer management is one of many ways to reduce emissions of nitrous oxide, and to keep our nitrogen where it needs to be for a crop.

Wes Anderson, vice president of agronomy with Croptimistic Technologies, has written a blog post on SWATMaps, all about nitrous oxide, the process of denitrification, and how to keep that investment where it’s needed.

The article was spurred by some of the action items that the federal government wants to implement surrounding emissions from fertilizer use — issues that Fertilizer Canada is also concerned about.

Anderson doesn’t think that government should be involved in making fertilizer decisions and as an industry professional — along with farmers, other agronomists, and fertilizer manufacturers — says there’s a need to get ahead of the issue, and prove that 4R nutrient management is adequate.

The article mentions that out of the three greenhouse gases — carbon dioxide, methane, and nitrous oxide — nitrous oxide doesn’t get as much attention as the other two, as GHG potentials are usually in relation to a carbon dioxide equivalent.

“The thing about nitrous oxide is that, frankly, there’s really nothing good about it,” says Anderson. “From a farmer’s perspective it means that if you’re emitting nitrous oxide, you’re losing nitrogen, simply put.”

This can mean losses through denitrification of nitrogen fertilizer that was applied — primarily a microbial process, where microbes use the oxygen from a nitrate molecule, under saturated soil conditions, which eventually transform that nitrogen fertilizer into nitrous oxide.

Minimizing the amount of nitrous oxide emitted will take a combination of multiple technologies, says Anderson. Work out of the University of Saskatchewan by Dr. Richard Farrell can point the way, in terms of solutions as his research looks at both the spatial and temporal release of nitrous oxide in various landscapes.

Nitrification inhibitors, products that hold nitrogen in an ammonium form, that can’t be converted to nitrous oxide, is one solution, but Anderson says using precision agriculture can help to manage costs of these types of products by focusing them in “hot spot areas” to minimize losses.

Hear a full conversation with Wes Anderson for more detail on how landscape position affects the denitrification process (story continues below player):

Identifying the high risk areas, where denitrification is most likely to occur, by mapping soils is step one, says Anderson. “Now with some clients that are really ahead of the curve, we have the ability to map soils and landscapes to identify those high-risk areas and really apply products in certain areas of high risk,” says Anderson.

For example, having two sources of nitrogen in one tank, or perhaps one source of nitrogen and the technology to inject nitrification inhibitor into certain parts of the field. Another example Anderson gives is having two sources of nitrogen in two tanks, and diversifying the nitrogen sources, depending on the denitrification risk of the landscape.

Anderson adds that 4R nutrient stewardship comes down to soil type, landscape position, and gravimetric water content. Using the various steps of The 4R nutrient stewardship program also isn’t an all or nothing thing, everything that’s done is a step in the right direction.

“All of those little steps are all increments in the right direction, but I guess what I’m seeing coming the industry is, if we don’t leap forward to that expert level of 4R nutrient stewardship, where we’re spatially managing things as well, the government might start imposing if for us,” says Anderson.

Related: Will the federal government cap synthetic fertilizer use?

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