Advances in Miscanthus × Giganteus Planting Techniques May Increase Carbon Uptake in the Establishment Year

Agricultural lands hold significant potential for CO₂ sequestration, particularly when utilizing biomass crops and agricultural residues. Among these, Miscanthus × giganteus (<i>mxg</i>) stands out due to its high productivity and carbon sequestration capabilities. Recognizing the importance of such biomass crops, the Intergovernmental Panel on Climate Change (IPCC) has identified Bioenergy with Carbon Capture and Storage (BECCS) as a crucial strategy for achieving net-zero CO₂ emissions by 2050. This study examines the carbon uptake potential of <i>mxg</i> during its establishment year at the Sustainable Advanced Bioeconomy Research (SABR) farm in Iowa, USA, where <i>mxg</i> was planted at a density exceeding previous studies. Using eddy covariance (EC) measurements, we quantified the net ecosystem carbon exchange (NEE), and derived gross primary productivity (GPP), and ecosystem respiration (<i>R</i> _eco). Our findings reveal that SABR's <i>mxg</i> exhibited a significant carbon uptake of -621 g C m^-2, a threefold increase compared to a similar EC site in the "corn-belt" (University of Illinois Energy Research Farm; UIEF), which was established with lower planting density and pre-commercial planting equipment. Favorable growing conditions and advanced planting technologies at SABR likely contributed to this high carbon uptake. Comparisons with other global EC studies indicated a strong correlation between higher planting densities and greater carbon uptake. These results suggest that increasing <i>mxg</i> planting density can enhance carbon uptake, but further studies are necessary to evaluate the impacts under varying environmental conditions and management practices. Additionally, economic analyses are essential to determine the viability of higher planting densities. Our study underscores the potential of optimized <i>mxg</i> management practices to contribute significantly to CO₂ uptake and supports the development of BECCS as a viable climate change mitigation strategy.