Climate change is affecting how potatoes grow in Canada, but there are ways to adapt your farm to weather the changes.
Editor’s note: This interview has been edited for length and clarity.
Spud Smart (SS): Is climate change a new thing for Canadian potato growers?
Stephanie Arnold (SA): It’s been a while since the temperatures here in P.E.I. the summer have stayed below 21 C as they did in the 1970s. And I’m not even sure how often we ever consistently got one inch of rain per week throughout the growing season.
I wanted to start here because growers have been adapting to changes in the climate for a very long time. So why do we all of a sudden have this intense focus on climate change adaptation? What we are focusing on is how the pace of change is accelerating. The speed of adaptation has to pick up like it’s never had too before.
The events will become more intense, the seasonal rainfall amounts will be impacted. And also, the type of events will change. We are already seeing many more rain events in our winter months than in years past.
SS: How can we use temperature changes to our advantage for growing potatoes?
SA: An increase in growing degree days can open up new options in the varieties and the types of crops we plant. And while a double harvest won’t be possible with potatoes it could be possible with rotational crops.
But of course, the good is balanced with the bad for potatoes. The stages of growth that’s most affected by heat stress are tuber initiation, vegetative growth and tuber bulking. When the temperatures are high and there’s more respiration, dry matter distribution favours developing foliage and so tuber dry matter suffer, and they can get unacceptably low especially for the processing industry. With the warmer temperatures, pests and weeds can overwinter become more productive, more invasive, and multiply faster.
SS: How is precipitation being affected by climate change?
SA: On the precipitation side, unfortunately, we don’t really expect any positives that can come from the change in precipitation patterns. And because warmer weather can hold more water vapour, we will also see longer periods between rain events. And when it does rain, it will become more intense. And so, you can see drought-like conditions and excessive soil moisture multiple times within the same season.
This higher temperature combined with irregular and intense rainfall can cause occasional flooding, which increases the risk of bacterial infections. And this excess soil water can also increase incidences of seed contamination.
SS: Is there a way potato growers can predict what is going to happen regarding climate?
SA: It’s difficult to be proactive when you are not sure what to base your decisions on. Can we look at averages? How do we use trends? We’re also uncertain about the types of impacts where and when they’ll happen and how severe there’ll be. And the temptation is to wait and see. That’s because you don’t want to spend your limited resource too early to prepare for an impact that might not come or might come later or isn’t as bad as we anticipate. There’s also a concern about whether or not you would bother spending the time and money on something if it’s not going to be enough when all is said and done. And there’s never a guarantee that what you’re doing will work.
The approach I’m using for potatoes in P.E.I. helps to remove some of that uncertainty, I look at what the external pressure points the farmers are facing, using climate projections to determine when they might trigger a need for adaptation action, and then lay out the different adaptation options so that growers can choose and sequence them in a way that makes sense for them.
SS: What can potato growers do on their farms to help with the impacts of climate change?
Ryan Barrett (RB): One thing that we’ve learned over the last number of years is that reducing nitrous oxide emissions is probably one of the major ways that farmers can reduce their impact on their impact on climate change. Nitrous oxide is many times more serious as a greenhouse gas than carbon dioxide.
So doing what we can to reduce nitrous oxide, whether it be reducing nitrogen or using a protected nitrogen source, like say ESN or Super U or Agrotain, something that maybe has a more of a slow-release process to it. Maybe it’s also planting a cover crop to make sure that you’re sequestering some of that nitrogen rather than having it lost to the system.
Then it’s also things like converting non-productive land or sensitive areas to permanent grass or permanent trees which sequesters carbon. Reducing tillage passes, which not only reduces fuel consumption, but also carbon released from the soil. So, it’s a kind of a double whammy.
SS: How can improving soil organic matter help with climate change?
RB: One big one is improving soil organic matter. It should not be news to anybody that increasing the organic matter level of our soil is associated with increasing the water holding capacity, helping to buffer changes in soil temperature and keep soil cooler. It also helps foster a healthy microbiome that suppresses disease and cycles nutrients. And of course, it’s sequestering carbon at the same time as building soil health.
What are we doing to do that in Prince Edward Island to build resiliency in our soils? We’re evaluating different crops and different mixtures that maximize root growth and maximize carbon sequestration. We’re evaluating crops and mixtures that feed the soil and build that soil organic matter, while at the same time suppressing diseases, that many of which are soil borne. And then we’re also evaluating crops and mixtures that naturally break up soil compaction without the need for deep tillage. So that can be things like daikon radishes or alfalfa crops that have deep tap roots that can help to break up the soil.
I think that cover cropping is a key way that we can introduce more resiliency in our systems. Not only do they reduce soil erosion, but they also reduce nitrate leaching and nitrous oxide emissions. So that retains that nitrogen for the next year, which means that hopefully, we can reduce the amount of nitrogen that we have to apply for the next for the next crop.
Header Photo — A cover crop of radishes in Prince Edward Island which helps improve soil organic matter. Photo: Ryan Barrett