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Science with a focus on applied problem-solving has an important role to play in building sustainable food systems, transitioning to clean energy, improving water quality, and supporting biodiversity.
FEWscapes researchers have been working for the past few years on various projects focused on these interconnected goals. Here are a few insights from their research.
Soil type matters when it comes to climate impacts on crops
An immense body of research has analyzed how climate change will affect production of the key crops we use for food, fuel, and fiber. These projections of future crop yields don’t always consider the effects of soil, however.
In a study published in Agricultural Systems, a research team that included FEWscapes principal investigator Chris Kucharik assessed US soil, climate, and crop data. They found that changes in temperature and precipitation affected crop yields more strongly in coarse-textured soils; comparable weather events caused less fluctuation in medium- and fine-textured soils.
This means farmers, farm advisors, and policymakers alike should be aware that areas with coarse-textured soils – including parts of the east coast, south, Nebraska, and the Great Lakes – are likely to see greater impacts on crop yield as the climate continues to warm.
Texture, which is determined by the mineral material in soil, is not the only factor that matters. The study demonstrated that the water retention properties of soil organic matter, or decomposing plant and animal material composed largely of carbon, can also have positive or negative yield effects.
Fields with more organic carbon – i.e., those with concentrations above 2% – generally lost less yield to heat and drought. In wet regions with poorly drained soils, though, increased organic matter can reduce crop yields by causing more soil saturation.
Read Huang, J., A. Hartemink, and C.J. Kucharik. 2021. Soil-dependent responses of US crop yields to climate variability and depth to groundwater. Agricultural Systems, 190: 103085.
There may be potential to artificially replenish declining groundwater tables in the Wisconsin Central Sands
“Managed aquifer recharge” is the practice of taking water from nearby rivers and spreading it onto fields where it will infiltrate into the soil and percolate downward to the water table. In the right circumstances, it can reverse groundwater depletion and make water available for ecosystems and irrigation. Land managers have put it into practice across the world, largely in arid or semi-arid regions like California’s Central Valley.
Former civil and environmental engineering master’s student Harold Barker studied the potential of this managed recharge in the Wisconsin Central Sands, where water availability is higher but groundwater tables have nonetheless declined. (Barker was advised by FEWscapes co-principal investigator Steven P. Loheide.)
Managed recharge in the region would involve diverting excess streamflow from snowmelt in the Wisconsin River into dedicated recharge zones. Barker used hydrological models to project the impacts of this practice and found that it does indeed have the potential to ameliorate groundwater depletion in the Central Sands.
Most studies of managed recharge tend to look at how it would impact one variable of interest: say, water for irrigation or for drinking water supply. But, in reality, aquifers face multiple competing demands from natural and human uses. Barker looked at the tradeoffs between groundwater supply (important for irrigation), forest productivity, and baseflow to trout streams.
There are a few pockets of the Central Sands where recharge could provide all three of those benefits. In most places, it would only be useful for one or two. And in some places, recharging aquifers wouldn’t generate any benefits in any of these areas.
These results point to the need to carefully consider priorities and tradeoffs when designing interventions like artificially replenishing aquifers.
Read Barker, Harold. 2023. Impacts of managed aquifer recharge on ecosystem services in a forested and agricultural landscape. University of Wisconsin-Madison master’s thesis.
Crop insurance serves row crop farmers better than pasture and livestock farmers, survey finds
In a survey on Midwestern farmers’ attitudes about Farm Bill financial programs, insurance products received higher marks from row crop farmers than from forage, grass-based livestock, and confinement livestock farmers.
The survey, led by recent PhD graduate Yu Lu and FEWscapes co-principal investigator Adena Rissman, found that 79% of respondents saw insurance as either “moderately” or “extremely” helpful for row crop production, compared to 40% for forage production, 35% for confinement livestock and just 30% for grass-based livestock systems.
A similar pattern held in opinions of insurance rules, premium cost, paperwork load, wait time, and staff performance.
All farms have bad years, and insurance is an important part of how farm enterprises manage risk. These results suggest that the lower usefulness of insurance programs might disincentivize deep-rooted perennial forage and pasture cropping systems that contribute more to soil health and water quality. In the absence of changes to insurance programs, it’s possible that this effect will become more pronounced as the threat of extreme weather grows in a warming climate.
Read the policy brief: Yu Lu, Adena Rissman, Lillian Herling, Maddie Olson, Eliza Eyman. 2024. “Midwest Farmer Perspectives on Farm Financial Programs.”
Wetlands alone are unlikely to resolve Gulf hypoxia
Can wetlands, by themselves, address nutrient pollution? No, says research led by collaborators at the University of New Hampshire and including FEWscapes principal investigator Chris Kucharik.
While wetlands remain a valuable tool for nutrient reduction, the results suggest that a portfolio of approaches will be necessary to fully achieve current targets.
The authors modeled the effects of two plausible, hypothetical large-scale wetland restoration programs designed to reduce hypoxic zone in the Gulf of America, an area of dissolved oxygen caused by nutrient pollution that harms fisheries, economies, and human livelihoods. This nutrient pollution comes from runoff from agricultural and urban land across the Mississippi River Basin.
Full implementation of the hypothetical programs would achieve between 10% and 60% of the nutrient reductions needed to meet Gulf of America dead zone reduction targets, a proportion lower than previous estimates.
The authors describe three reasons for this finding. First, they found that wetlands intercept less nutrient runoff than expected. Past studies, they say, underestimated how much agricultural runoff ends up stored in deep groundwater, where it continues to flow into the Gulf over long time horizons.
Second, many areas suitable for wetland restoration are geographically disconnected from heavily fertilized croplands, which means they are less likely to capture nutrients from lands that are contributing the most nutrient runoff. And third, the times of year when wetlands are most effective at filtering nutrients are not the times of year when farmers apply fertilizer.
Read Zuidema, S., W. Wollheim, C.J. Kucharik, and R. Lammers. 2024. Existing wetland conservation programs miss nutrient reduction targets. Proceedings of the National Academy of Sciences Nexus, https://doi.org/10.1093/pnasnexus/pgae129.
After expansion of the US Renewable Fuel Standard in 2007, fertilizer use increased by 3-8%
The US Renewable Fuel Standard is the world’s largest existing biofuel program. In 2022, FEWscapes researchers Chris Kucharik and Eric Booth joined researchers from several universities to assess the program’s environmental outcomes.
Their work found that, after the amount of ethanol required to be blended into fuel was increased in 2007, American farmers expanded their total cropland area by about two million hectares, or a little over 2% nationally. Because of these changes, nationwide fertilizer use increased by 3 to 8% and water quality pollutants increased by 3 to 5%.
The Renewable Fuel Standard was passed with the goal of decreasing the carbon emissions intensity of fuels. But because increased demand for corn ethanol led to conversion of natural landscapes into cropland, these findings indicate the carbon intensity of corn ethanol produced under the policy is likely substantially higher than gasoline without ethanol.
To arrive at these results, the team looked at the first eight years after the expansion of the Renewable Fuel Standard ethanol requirements in 2007. They conducted an economic analysis of how the policy affected crop production and analyzed the environmental impacts of that production. They then compared these results to a “business-as-usual” scenario, in which the Renewable Fuel Standard is not expanded and remains at the levels set in 2005.
When the results were first published, Booth argued that they called for a broad conversation about the future of corn ethanol production. There could still be room for biofuels to play an important role in combatting global warming, though. Achieving this goal, authors say, would likely require replacing corn ethanol with perennial feedstocks, and growing those feedstocks on marginal lands.
Read Lark, Tyler J., Nathan P. Hendricks, Aaron Smith, et al. 2022. “Environmental Outcomes of the US Renewable Fuel Standard.” Proceedings of the National Academy of Sciences 119 (9): e2101084119.
Header photo: A wetland in Hardin County, Iowa. By Lynn Betts, Soil and Water Conservation Society.