Date of Defense

4-16-2025

Date of Graduation

4-2025

Department

Biological Sciences

First Advisor

Kathryn Docherty

Second Advisor

Steven Bertman

Abstract

Conventional agricultural practices that transform natural ecosystems from cropland rely on methods such as tilling, pesticide application, and fertilization. These practices have a substantial impact on soil health, fertility, and stability, which can result in soil loss and lower crop yields. Particularly, conventional agricultural practices reduce the overall amount of soil organic matter and can change the proportions of carbon stored in the particulate organic matter (POM) and the mineral-associated organic matter (MAOM) fractions. Conservation efforts - such as marginal area prairies and prairie strips - that can be used within conventionally managed agricultural systems can help reduce these negative effects on soil health. However, the extent to which plant seed mix richness influences these benefits remains unclear. This study evaluates the impact of four land management strategies on soil organic carbon pools, microbial biomass, and overall soil health. In 2023, we leveraged treatments in the Conservation Lands Experiment located at Michigan State University’s Kellogg Biological Station. We sampled from sites representing four land management treatments: conventional agriculture, abandoned old fields, and prairies restored using a 12-species seed mix and a 70-species seed mix. The prairie restorations were implemented in 2015 on abandoned old fields and managed with biannually prescribed fire. We measured microbial biomass carbon, respiration, total carbon, permanganate oxidizable active carbon (POXC), total soil organic matter (SOM), particulate organic matter carbon (POM-C), and mineral-associated organic matter carbon (MAOM-C). Agricultural soils exhibited the lowest levels of active carbon and microbial biomass of the four treatments, while the two prairie restorations and the old field sites had higher, but similar, levels of microbial biomass and activity, active carbon, SOM, POM-C, and MAOM-C. However, the relative differences in POM-C among the treatments suggest a trend that soils in the restorations are on a trajectory to accumulate more POM-C than the old fields. This was not a pattern we observed in the MAOM-C fraction, so this result may indicate that the historical legacy of abandonment led to an accumulation of MAOM in the restorations, but seeding with native species and fire management are ways that can promote continued contribution to organic matter as POM. These findings highlight the value of including native plant installations and reducing tillage as strategies to improve soil health in agricultural management.

Access Setting

Honors Thesis-Restricted

Restricted to Campus until

6-3-2027

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Available for download on Thursday, June 03, 2027

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