In Can Farms Pull Carbon from Sky to Soil? (Grow, summer 2023), Hal Conick highlighted the early stages of an ongoing long-term study by a group of agronomy researches. Their goal is to see if improved agricultural practices can sequester carbon and slow climate change.

The study measures the impact on a variety of soil types over time by analyzing two decades of sampling data from a longitudinal cropping trial at UW. It also evaluates data from multiyear experiments at two other Midwestern universities and two networks of research sites on multiple Midwestern farms. In addition, the study uses a deeper soil sampling method to improve the accuracy of their carbon measurements. Early results indicated that grazed pasture and perennial grasslands.

And the work continues. In July 2024, the team, including Ph.D. student and lead author Clare Dietz MS’ 22, published findings in Communications Earth & Environment that support the study’s early indications. Through an analysis of changes in soil organic carbon (SOC) stocks under six cropping systems and a restored prairie in UW’s longitudinal trial, the team found that cash-gain and alfalfa-based systems lost SOC over time. Prairie and rotationally grazed pasture, on the other hand, stored carbon effectively (i.e., SOC levels in these systems remained stable).

The findings demonstrate the improved accuracy of the research team’s more comprehensive methods, less thorough methods would have overestimated the ability of these systems to sequester SOC. The study also highlights the need for well-managed grasslands to protect SOC in the Upper Midwest’s agricultural soils.

This article was posted in Changing Climate, Fall 2024, Follow-Up, Healthy Ecosystems and tagged alfalfa, cash-grain crops, climate change, longitudinal cropping trial, perennial grasslands, rotational grazing, soil organic carbon, Wisconsin Integrated Cropping Systems Trial.