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ARS Home » Plains Area » Temple, Texas » Grassland Soil and Water Research Laboratory » Research » Publications at this Location » Publication #425983
Research Project: Enhancing Cropping System and Grassland Sustainability in the Texas Gulf Coast Region by Managing Systems for Productivity and Resilience

Location: Grassland Soil and Water Research Laboratory

Title: Experimental warming effects on soil respiration and microbial community function in switchgrass cropland in Middle Tennessee

Author
item LI, JIANWEI - Tennessee State University
item GAMAGE, LAHIRU - Tennessee State University
item JIAN, SIYANG - University Of Oklahoma
item WANG, XUEHAN - Tennessee State University
item ALFORD, JONATHAN - Tennessee State University
item MANU, MATTHEW - Tennessee State University
item PANDEY, AVIYAN - Tennessee State University
item DE KOFF, JASON - Tennessee State University
item HUI, DAFENG - Tennessee State University
item Fay, Philip

Submitted to: Global Change Biology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/2/2025
Publication Date: 9/17/2025
Citation: Li, J., Gamage, L., Jian, S., Wang, X., Alford, J., Manu, M., Pandey, A., De Koff, J., Hui, D., Fay, P.A. 2025. Experimental warming effects on soil respiration and microbial community function in switchgrass cropland in Middle Tennessee. Global Change Biology. https://doi.org/10.1111/gcbb.70066.
DOI: https://doi.org/10.1111/gcbb.70066

Interpretive Summary: Global warming is projected to accelerate losses of soil carbon to the atmosphere, however, experimental studies of the mechanisms by which warming affects soil carbon losses to the atmosphere from soil respiration CO2 emissions from perennial bioenergy crops such as switchgrass have rarely been conducted. Identifying warming effects and mechanisms in switchgrass is necessary to accurately quantify the benefits of switchgrass bioenergy cropping systems. This study reports results from a two year warming experiment in a switchgrass cropland. High frequency measurements of soil respiration coupled with measurements of soil carbon pools and microbial enzyme activities revealed that experimental warming increased rates of soil respiration, primarily because warming increased the microbial pool of carbon and soil temperature while decreasing soil moisture. The experiment will be continued into the future to identify how these trends continue.

Technical Abstract: Global warming is projected to accelerate soil carbon (C) loss to the atmosphere. However, soil CO2 emissions under warming and the underlying microbial processes are not adequately studied in bioenergy croplands. To address this issue, a soil warming experiment was established in a switchgrass cropland at Tennessee State University in May 2021. Four paired plots with infrared and dummy heaters (i.e., warming vs. control plots) were randomly installed in four blocks. Collections of hourly soil heterotrophic respiration (Rs), temperature, and moisture at surface soil (0-10 cm), as well as biweekly soil organic carbon (SOC), total nitrogen (TN), microbial biomass carbon, and nitrogen (MBC and MBN), and extracellular enzyme activities (EEAs) were conducted consecutively for two years. Warming elevated soil temperature by 2.2', reduced volumetric water content by 17.5%, and significantly increased hourly Rs but had no significant effects on the contents of SOC, TN, MBC, MBN, and soil EEAs. Despite the insensitive responses of soil microbial, enzymatic, and bulk features, the elevated Rs was closely associated with warming-caused changes in soil microbial biomass, soil temperature, and moisture. Overall, the elevated Rs in response to 2-year experimental warming informed a likely positive response of switchgrass soil CO2 emission to a warmer future and a shift toward increased autotrophic respiration. The current study implied the importance of long-term experimental observations to accurately predict soil respiratory responses in switchgrass croplands.