Conversion of marginal land into switchgrass conditionally accrues soil carbon and reduces methane consumption

Authors: BATES, COLIN - University Of Oklahoma; ESCALAS, ARTHUR - University Of Montpellier; KUANG, JIALIANG - Oklahoma State University; Hale, Lauren; WANG, YUAN - Noble Research Institute; HERMAN, DON - University Of California; NUCCIO, ERIN - Lawrence Livermore National Laboratory; WAN, XIAOLING - Chinese Academy Of Sciences; BHATTACHARYYA, AMRITA - Lawrence Livermore National Laboratory; FU, YING - University Of Oklahoma; TIAN, RENMAO - University Of Oklahoma; WANG, GANGSHENG - University Of Oklahoma; NING, DALIANG - University Of Oklahoma; YANG, YUNFENG - Tsinghua University; WU, LIYOU - University Of Oklahoma; PETT-RIDGE, JENNIFER - Lawrence Livermore National Laboratory; SAHA, MALAY - Noble Research Institute; CRAVEN, KELLY - Noble Research Institute; BRODIE, EOIN - University Of California; FIRESTONE, MARY - University Of California; ZHOU, JIZHONG - University Of California

Submitted to: The ISME Journal: Multidisciplinary Journal of Microbial Ecology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/27/2021
Publication Date: 7/1/2021
Citation: Bates, C., Escalas, A., Kuang, J., Hale, L.E., Wang, Y., Herman, D., Nuccio, E., Wan, X., Bhattacharyya, A., Fu, Y., Tian, R., Wang, G., Ning, D., Yang, Y., Wu, L., Pett-Ridge, J., Saha, M., Craven, K., Brodie, E.L., Firestone, M., Zhou, J. 2021. Conversion of marginal land into switchgrass conditionally accrues soil carbon and reduces methane consumption. The ISME Journal: Multidisciplinary Journal of Microbial Ecology. https://doi.org/10.1038/s41396-021-00916-y.
DOI: https://doi.org/10.1038/s41396-021-00916-y

Interpretive Summary: A deeply-rooting, perennial, biofuel crop, switchgrass, has potential to mitigate climate change and enhance soil fertility by sinking carbon into soils. Switchgrass cultivated in marginal soils impacted soil greenhouse gas emissions and microbial community characteristics, which were site-specific effects. Enhanced soil carbon content, but reduced methane consumption in switchgrass cultivated soils indicated that if evaluated for climate mitigation, total soil carbon fluxes need to be considered.

Technical Abstract: Switchgrass can be cultivated on soils with low nutrient contents, and its rooting depth, of up to 2 m, has brought attention to the crop with a great potential to sequester soil carbon (C). However, to fully evaluate the sustainability of switchgrass-based biofuel production, it is crucial to understand the impacts of switchgrass establishment and land conversion on biotic/abiotic characteristics of various soils. Here, we characterized the ecosystem-scale consequences of switchgrass at two ‘Dust Bowl’ remnant field sites (designated SL and CL) in Oklahoma, which are low in nitrogen (N) and phosphorus (P) nutrient availability, C content, and have a high erosion history. Paired plots at each site, including a control fallow plot and a plot cultivated with switchgrass, were assessed by profiling (i) physicochemical soil characteristics, (ii) the biodiversity of prokaryotic communities, and (iii) greenhouse gas (GHG) fluxes (CO2, CH4, and N2O). Switchgrass significantly increased soil C at the SL site and reduced microbial diversity at the CL site. Strikingly, switchgrass significantly reduced the CH4 consumption by an estimated 39% and 47% for the SL and CL sites, respectively; implying carbon balance considerations may need to be accounted for to evaluate the sustainability of switchgrass cultivation fully. Together, our results suggest that site selection by soil type is a crucial factor in improving soil C stocks and mitigating GHG fluxes.