Scientists Examining Stover Harvesting for Ethanol

5-year USDA project studies impact on soil health and productivity

Apr. 18, 2026 at 5:41am

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A bold, abstract painting in earthy tones depicting the interconnected forces of soil nutrients, carbon cycling, and biofuel production through sweeping geometric shapes and precise botanical patterns, conveying the structural complexity of sustainable agriculture.A conceptual visualization of the delicate balance between biofuel production and soil health that researchers are working to define through the REAP project.Lincoln Today

Researchers from the USDA, state universities, and the Department of Energy are conducting a 5-year study called the Renewable Energy Assessment Project (REAP) to determine the optimal amount of corn stover that can be harvested for ethanol production without harming the soil. The project is examining factors like soil erosion, nutrient replacement, and carbon sequestration to establish guidelines for no-till farmers and ethanol producers.

Why it matters

Harvesting corn stover for cellulosic ethanol could reduce dependence on crude oil, but removing too much stover can negatively impact soil health and productivity. This research aims to find the right balance to support both renewable energy and sustainable agriculture.

The details

The REAP project is studying field sites across 13 USDA Agricultural Research Service locations and state universities. Researchers are looking at the effects of stover harvesting on organic matter content, grain yields, and carbon sequestration in soils with varying productivity levels. They are also testing cover crops and living mulches to see if those can help maintain soil health when stover is removed.

  • The second season of field studies is wrapping up in 2026.
  • The full 5-year REAP project is scheduled to conclude in 2028.

The players

USDA Agricultural Research Service

A network of research locations conducting the Renewable Energy Assessment Project (REAP) to study the impacts of corn stover harvesting.

Wally Wilhelm

A plant physiologist at the USDA ARS Agroecosystem Management Research Unit in Lincoln, Nebraska, who is coordinating the REAP research.

Gary Varvel

A scientist at the USDA ARS in Lincoln, Nebraska, who is working with Wally Wilhelm on a 100-acre study examining the effects of stover harvesting.

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What they’re saying

“REAP aims to establish stover-management guidelines that would help no-tillers, ethanol producers and...”

— Wally Wilhelm, Plant physiologist, USDA ARS

What’s next

The REAP project is scheduled to continue field studies for 3 more years to gather comprehensive data on the long-term impacts of stover harvesting.

The takeaway

This research is critical for finding the right balance between renewable energy production and soil health preservation. The guidelines developed through REAP will help farmers, biofuel producers, and policymakers make informed decisions about sustainable stover harvesting practices.