Potato greenhouse gas emissions can be reduced through proper fertilizer usage, according to these fertilizer industry experts.
EXPERTS:
Editor’s note: This interview has been edited for length and clarity.
Spud Smart (SS): What is 4R Nutrient Stewardship?
McKenzie Smith (MS): It’s pretty straightforward in terms of what it means. It is a sustainable way of applying your nutrients and it includes the right source, which means applying the balanced supply of all nutrients that are needed by the crop — macronutrients like N, P and K, along with micronutrients.
Right rate is the amount of those nutrients that you would apply. It is considering organic sources like manure and nutrients that are already in the soil, taking a soil sample and then adding fertilizer to ensure that the right amounts of each necessary nutrient is available to the crop in the right proportions.
And then right time and right place, pretty self-explanatory, applying nutrients at a time when the crop can use them best, during the certain crop growth timeframes or avoiding before a big rainfall event. And then right place, same idea. Applying those nutrients subsurface below the soil next to the root type, so that the nutrients can be optimized by the crop and taken up, and in turn reducing the potential loss of those nutrients to our environment through volatilization to air, or through runoff to water.
SS: How do you determine the right source when it comes to fertilizer?
MS: Obviously across Canada, the right nutrient source will likely differ. The type of fertilizer that would be best suited for a canola crop in Western Canada on dry soil versus a corn crop in central Canada, or more specifically to this conversation, potato production in Atlantic Canada.
The source is what you need to determine first in terms of what is needed to be applied to that specific crop, and then what type of source depends on soil and climatic conditions to best optimize nutrient uptake. Additionally, it’s important to ensure a balanced supply of nutrients, so you’re not adding more nutrients or something that’s already there in the soil or already applied with an organic source like manure but looking at what is missing and making sure its present in your prescription.
Taking into account how much of those nutrients that you’re looking at are available in the soil and sources applied with fertilizer, then you can determine how much of those nutrients are needed to balance supply…Looking at what is in the soil by taking a soil sample is one of a few ways that you can determine the right rate to apply, especially after a crop rotation.
SS: What impact does potato production have on greenhouse gas emissions?
Erika Wagner (EW): Globally, agriculture contributes to about 20 per cent of greenhouse gas emissions. And of that 20 per cent, five per cent comes from mineral fertilizer use and six per cent comes from mineral fertilizer production. Let’s look at greenhouse gas emissions in the potato industry, using the life cycle assessment of a frozen french fry.
On-farm emissions make up about 18 per cent of total emissions of that final frozen french fry product. Whereas the activities at the processor make up about 33 per cent of the overall emissions, retailer 11 per cent, and consumer and foodservice actually make up about 38 per cent of overall emissions. There are a lot of factors that make up the final lifecycle assessment for a french fry, and as an industry, there’s a potential to reduce emissions at many points in the lifecycle.
For on-farm emissions, there may be years where our greenhouse gas emissions per french fry are really low, because we had a great yield great quality, favourable weather, and used inputs efficiently to drive higher yield and reduce losses. But there also may be years where there are unexpected weather events, which happens more often than not these days where maybe the yields are a little lower, or quality issues arise leading to higher greenhouse gas emissions per french fry. So, the on-farm emissions may increase or decrease from year to year, but that may be able to be balanced by reduced emissions at a different point in the cycle.
SS: How can you reduce on farm fertilizer emissions as a potato grower?
EW: One consistent way is to choose inputs that are manufactured with processes that have a low carbon footprint. At Yara we’ve actually been working to reduce our emissions in the manufacturing process for 20 years. We’re leading in reducing emissions in the manufacturing of nitrate fertilizer through the use of nitrous oxide abatement catalyst technology and energy efficient measures.
So already our nitrate-based EU-produced fertilizers have a 50 to 60 per cent lower carbon footprint compared to other non-EU fertilizers. In the future, we’re also looking at using renewable energy resources in addition to the abatement catalysts to reduce our emissions in manufacturing by 90 to 95 per cent. So just by choosing inputs that have manufacturing process with low carbon footprints, you can lower your emissions of your on-farm potato production.
SS: Why is it important to sustainability to manage tuber quality at harvest and storage?
EW: The idea here is really to provide the crop with the nutrients that it needs to grow a high-quality crop in the grade you’re looking for in the end, which should reduce waste, it should reduce loss in storage, and it should reduce waste at the processor.
For tuber grade, if you’re growing a seed crop or a chip crop and you want a higher tuber set, I’d recommend making a phosphorus application at tuber initiation. Calcium can also increase tuber size, it’s very important for tuber quality. I would recommend using calcium but also making sure to use the shot of phosphorus at tuber set initiation.
Everyone knows that nitrogen is an important nutrient for the crop. But it’s also important to manage your nitrogen well, because too much nitrogen particularly late in the season can negatively impact quality. It can negatively impact skin finish and skin set and can increase susceptibility to bruise and can also lead to growth cracks and more incidences of internal blemishes.
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