Source: Michigan State University AgBioResearch

By Holly Whetstone

A study authored by Michigan State University (MSU) soil biologist Lisa Tiemann is the first of its kind to show that crop rotations, in isolation from other management factors, can increase the functions performed by soil microbial communities that benefit plant growth.

The findings were published online May 25 in the peer-reviewed journal Ecology Letters.

Research for the project took place at the W.K. Kellogg Biological Station, an MSU research center in Hickory Corners, Mich., northeast of Kalamazoo. In the paper, Tiemann and her co-authors address the relationships among crop rotational diversity, soil structure, microbial community structure and activity, and soil organic matter chemistry.

“Although the aboveground benefits of crop diversity have been well-documented, the belowground effects remain uncertain,” Tiemann said. “Understanding how crop diversity alters microbial community dynamics and the specific mechanisms controlling positive impacts of biodiversity belowground is critical for sustainable soil management.”

 A byproduct of increased pressure on soils from agricultural intensification is a negative impact on microbial diversity. Over-farming is problematic worldwide and can lessen soil’s ability to perform important ecosystem functions. Results may include threats to long-term food security, increases in greenhouse gas emission, flooding and a reduction in water quality.

Researchers sought to combat these challenges through crop rotation, restoring positive interactions above- and belowground by increasing biodiversity. The group concluded that a diverse set of crops can sustain soil biological communities, with positive effects on soil organic matter and soil fertility.

“The data we present are the first to support the hypothesis that increasing rotational diversity fundamentally changes microbial community structure and activity, with positive effects on aggregate formation and soil organic matter accrual,” Tiemann says. “These findings provide further support for the use of rotational diversity as a viable management practice for promoting agroecosystem sustainability.”

Tiemann, whose work is funded in part by MSU AgBioResearch, indicated that this knowledge can ultimately be used to help land managers determine how to maximize soil sustainability, particularly in low-input cropping systems.

Co-authors for the study are Stuart Grandy and Marshall McDaniel, Department of Natural Resources and the Environment at University of New Hampshire; and Emily Atkinson and Erika Marin-Spiotta, Department of Geography at University of Wisconsin-Madison.

The study was supported by the USDA Soil Processes Program, the U.S. Department of Energy Office of Science, the Office of Energy Efficiency and Renewable Energy and the U.S. National Science Foundation Long-Term Ecological Research Program.