Study verifies crop rotation benefits, eVGN July 2015
Results from a new study show crop rotation has a positive impact on soil microbial communities and long-term land sustainability.
“This knowledge can ultimately be used to help land managers determine how to maximize soil sustainability, particularly in low-input cropping systems,” said Lisa Tiemann, the study’s author, who is an assistant professor in Michigan State University’s (MSU) Department of Plant, Soil and Microbial Sciences.
The study is being touted as 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 Ecology Letters, a peer-reviewed journal.
Research for the project took place at the W.K. Kellogg Biological Station, an MSU research center in Hickory Corners, Michigan. 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,” she said. “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 could sustain soil biological communities, with positive effects on soil organic matter and 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 said. “These findings provide further support for the use of rotational diversity as a viable management practice for promoting agroecosystem sustainability.”
In her work, Tiemann views soil organic matter (SOM) dynamics and nitrogen cycling through a microbial lens.
“With a new, microbially oriented view of SOM formation, microbial community structure, biofilm formation, microbial productivity and microbial growth efficiency are all factors likely to influence and contribute to SOM formation and stabilization,” she said. “However, these factors have rarely been explored in this context. This emerging area of research provides a framework for testing questions and about soil microbial community dynamics in relation to environmental change and important ecosystem services such as soil fertility and nitrogen cycling.”