Ag Policy Blog

Purdue Study Examines Indiana Agriculture Climate Risks

Chris Clayton
By  Chris Clayton , DTN Ag Policy Editor
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Corn yields could decline up to 20% by mid-century in Indiana, according to a Purdue University study. The impacts, however, could be offset by changes in crop genetics, soil health improvements and other changes in cropping systems. (DTN file photo by Chris Clayton)

Warming temperatures are likely going to cause shifts in Indiana crop production in the coming decades, according to a study released earlier this week by Purdue University's Climate Change Research Center.

The report focusing on Indiana agriculture noted warmer overnight temperatures already have reduced corn yields in Indiana over the last decade. Those higher temperatures overnight have reduced yield potential about 2%.

At the moment, though, USDA is reporting good crop conditions for Indiana with 69% of the corn crop in good or excellent condition, according to this week's Crop Progress report. The soybean crop is listed at 67% in good or excellent condition.

Still, a warming climate is having an impact on how the soil interacts with the atmosphere, according to a separate study published this week in the journal Nature. Droughts and wildfires are heating up the soil, leading to more carbon dioxide releases from the soil.…

Purdue's study cited that more frequent heat stress and doubling of water deficits will reduce Indiana corn yields for current seed varieties 16% to 20% by mid-century. Soybean yields will be impacted by 9% to 11%. Driving the risks for declining yields will be hotter summer months, but these yield declines can be offset with changes in cropping systems, planting dates, crop genetics, soil health and supplemental irrigation along with drainage management.

"For the average corn and soybean farmer, our message is they already struggle with the variabilities of weather in Indiana," Bowling said. "They already know what these patterns look like," Bowling said. "They have way too much water in the spring then often in those same years there's not enough water toward the end of the growing season. So for them this pattern is the same. What we're projecting is it might become more pronounced -- more water in the spring, less water in the summer, and more often."

Bowling added, "Too much water or too little water are more likely to happen more often."

The baseline line for yield decline comes from current varieties so there is no modeling for possible yield improvement because of new crop varieties and technology.

"In that case, it's how would today's crops, today's varieties, respond to changing weather conditions," Bowling said.

Rising temperatures will extend the growing season, providing opportunities to grow different varieties of crops and double crop in some areas of the state as well. But temperature increases will also translate into more heat stress days as well, the Purdue report stated.

The study also highlights how Indiana farmers have increased subsurface tile drainage, to the point that about half of Indiana cropland is tiled, largely to help farmers get into their fields in the spring, Subsurface drainage in the spring is projected to increase 32% to 48% by mid-century (essentially one to two inches of rainfall) which could translate into greater risk of nutrient loss.

At the same time, hotter summers with lower precipitation will also lead to greater irrigation potential in the state. The difference between growing season rainfall and water demand for the crops is expected to double by mid-century. The deficit could rise from 3.7 increase to as high as 8.1 inches. Still, Purdue researchers also question whether irrigation equipment and usage costs would pay out for Indiana farmers in parts of the state even under drier conditions.

Researchers also looked at the possibility of farmers converting to crops such as winter wheat. "We do see potential, especially in the southern parts of the state, for double cropping with winter wheat and soybeans, for example," Bowling said. "We do think there is evidence that could become a more profitable rotation."

Indiana has been one of the more aggressive states in using cover crops to build soil health, an effort heavily championed by the USDA Natural Resources Conservation Service in the state.

"Certainly there are some that are not as eager to adopt that mindset but we have met other farmers in a focus group who will fully admit that they are part of the cult. They will describe it that way as the cult of soil health. There are a lot of people adopting or at least experimenting on how to use cover crops on their fields and thinking about how to build up organic matter. We support that message in order to better manage water, to drain the water more quickly in the spring, and hold a little bit more water into the summer, that the soil-health message is very consistent with that."

Pests and diseases are really the wildcard in all of this and to explore them would be an entire study unto itself because people can make progress in projections of one particular pest, Bowling said. "There will be some positive changes that some beneficial insects might spread, but it does seem that there is more potential to be more negatives than positives."

Livestock producers in the state are also going to have to cope with rising temperatures and more days when livestock and poultry experience heat stress. Producers will have to spend more money on ways to help keep their animals cool. A longer growing season could have some positive impacts on forage production, but forages also could lose protein content that would impact the quality of hay as well.

Fruits and vegetables cropped in Indiana also are likely to change with those hotter summers. Popular apple varieties grown in the state, such as Honeycrisp and Golden Delicious, may be replaced with other apple varieties as well. Other produce crops also will likely require more pesticide and fungicide applications as well.

Climate change can still be a taboo topic among most farm groups but there are elements of climate resiliency in groups such as the Soil Health Partnership led by the National Corn Growers Association. The American Farm Bureau Federation is also hosting Field to Market meetings in their offices.

"We're still doing the dance where there's hesitation to call it what it is but I'm glad there are a lot of different voices addressing this in their own best terms," said Tom Driscoll, who works on climate issues at the National Farmers Union. "I think we miss some opportunities when we can't say 'climate change' because it allows for a more integrated approach, but I'm glad there are people out there reaching folks in whatever way because it's becoming increasingly urgent."

Driscoll said farmers are more likely to pay attention to a study done by an in-state land-grant university than one released by a federal agency.

"I think it's great when reports go state-specific and it's not written by the EPA," Driscoll said. "Localizing the impacts and really talking about what's going to happen in this watershed, or this county, or how yields for a commodity are going to be impacted is really critical. Because when we talk about sea-level rising and melting polar ice caps, nobody's really sure what that means on his or her farm."

More information on the study can be found at the Purdue Climate Change Research Center…

Chris Clayton can be reached at

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