Soil Organic Matter Across a Chronosequence of Cultivated Switchgrass (Panicum virgatum)

Waidelich, Elsa

Soil Organic Matter Across a Chronosequence of Cultivated Switchgrass (Panicum virgatum)

Persistent URL

https://hdl.handle.net/10456/59217

Author(s)

Waidelich, Elsa

Date Issued

March 21, 2025

Abstract

Switchgrass (Panicum virgatum) is an indigenous North American warm season grass developed as a perennial biofuel crop. Switchgrass cultivation has the potential to improve or protect certain soil properties, but there is mixed evidence on the effect of continuous switchgrass cultivation on soil organic matter (SOM). In this study, I collected soil and biomass samples from switchgrass stands of different ages (1-17 years) to investigate the effect of age, aboveground biomass (AGB), and belowground biomass (BGB) on SOM concentration and mass. SOM concentration had no correlation with stand age, and SOM mass was negatively correlated (R2=0.51) to stand age. BGB and total biomass displayed no correlation to stand age, though BGB and total biomass were lowest for the youngest stand. AGB was negatively correlated (R2=0.35) with stand age. AGB was positively correlated weakly with SOM concentration (R2=0.12) and more strongly with SOM mass (R2=0.88), despite annual AGB harvest. BGB was positively correlated with SOM concentration (R2=0.67; p=0.046) but not correlated with SOM mass. These results suggest that SOM and biomass respond to variation within sites and, although SOM was not shown to accumulate in older sites, the concentration of SOM was not found to be depleted over years of continuous switchgrass cropping. This work contributes to the evolving understanding of SOM dynamics under switchgrass and perennial cropping systems which will inform biogeochemistry modeling and agro-ecosystem management.

Major

Environmental Science and Sustainability

Honors

Environmental Science and Sustainability, 2025

First Reader(s)

Bowden, Richard D.