Spring and summer 2024 have had no shortage of extreme weather. From flash flooding, hailstorms, wind and everything in between, this year’s crops have seen it all.
Justin Glisan, state climatologist of Iowa, shared on a recent webinar with Iowa Learning Farms that he has seen this trend slowly becoming more common for a few years now.
“Annual precipitation just over the last 16 years [in Iowa] has been several inches above average. If you look at the two-year intervals, 2018 and 2019 were the wettest two years on record,” Glisan says. “In the recent term, we’ve been seeing wetter conditions, and this has implications on runoff and aerial flooding.”
He says it’s clear we’re locking in on higher intensity events more often, and the management practices farmers adopt now will have a significant impact down the road.
This chart shows Glisan’s projections of what the average temperature will look like in 2050 with and without an increase in conservation farming practices.
“In the next 25 years, there’s the potential of anywhere from an increase of 2.5°F in the temperature record up to a 10-degree increase,” he says. “At the worst-case scenario, you’re raising the temperature by 10 degrees, and that’s 40% more water vapor in the atmosphere to work off of. That’s where we’re going to see increasingly extreme events with impacts on flooding and our conservation practices.”
With more water vapor comes higher humidity, which has implications for livestock health and can lead to higher temperatures and more frequent extreme rainfall events. Glisan says while increased moisture could help with drought stress in row crops, it also means higher overnight lows and more instability in the atmosphere.
How Conservation Practices Can Help
To trend closer to the lower emissions path, Glisan believes more of both in-field and structural conservation practices will need to be adopted.
“We know that with these higher intensity rainfall events falling on bare soil, it loosens up the soil profile, and we get more runoff. To keep that on the landscape, we look to cover crops, rotation diversity, prairie strips or a perennial cover on the land surface,” he says. “We also need to keep the water where it should be. For that, we think of terraces, wetlands and farm ponds.”
He suggests five methods to help adapt your operation:
1. Integrate alternative crop species with conservation crop rotations to maintain or improve soil health.
2. Choose crop species and varieties that are more suited to future conditions, including heat tolerance and water stress.
3. Use cover crops or reduce tillage to increase infiltration and water-holding capacity while building soil strength and aggregation.
4. Choose longer maturity corn cultivars to take advantage of a longer growing season, or plant shorter maturity corn varieties earlier in the season to avoid reproductive stages happening during the worst risk of drought in late summer.
5. Be prepared with farming strategies that help manage too much soil moisture in the spring — cool season cover crops or improved drainage — and not enough soil moisture during late summer — high-residue systems, drainage water recycling or controlled drainage structures.
