Chemical characteristics of the aboveground tissues of Miscanthus × giganteus and relationships to soil characteristics

Authors: Pisani, Oliva; Klick, Sabrina; Strickland, Timothy; Pisarello, Kathryn; Coffin, Alisa

Submitted to: BioEnergy Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/28/2023
Publication Date: 1/9/2024
Citation: Pisani, O., Klick, S.A., Strickland, T.C., Pisarello, K., Coffin, A.W. 2024. Chemical characteristics of the aboveground tissues of Miscanthus × giganteus and relationships to soil characteristics. BioEnergy Research. https://doi.org/10.1007/s12155-023-10718-z.
DOI: https://doi.org/10.1007/s12155-023-10718-z

Interpretive Summary: There is a growing need for alternative energy sources including the production of bioenergy feedstocks such as Miscanthus × giganteus. The chemical composition of biomass tissues can provide information on feedstock quality for biofuel conversion and crop residue impacts to soil input management. However, not much is known on the chemical composition of Miscanthus leaves and stems and their relationships with soil carbon (C) and nitrogen (N). Miscanthus leaf and stem chemistry data including C, N, nutrient concentrations, and the composition of the water extractable organic matter (WEOM) was analyzed to determine which soil variables may be correlated with tissue chemistry. Leaves and stems were dominated by N, potassium (K), calcium (Ca), phosphorus (P), and magnesium (Mg). The leaves contained higher nutrient concentrations compared to the stems, suggesting a lower biofuel quality. Leaf WEOM contained larger and more complicated structures compared to stem WEOM which was dominated by smaller, fresh structures. Varying relationships were found between tissue nutrients and the soil mobile C and N, suggesting a dynamic linkage between Miscanthus physiology and these active soil C and N pools that supply plant-available nutrients for crop growth. Miscanthus leaves had a chemical composition indicative of reduced biofuel quality. These results provide insight on the complex interactions between plants and soil.

Technical Abstract: To reduce the C footprint of human activities, there is a growing need for alternative energy sources including the production of bioenergy feedstocks. Miscanthus × giganteus is a high yielding grass with low environmental impact and high potential for feedstock use. Studying the composition of the aboveground tissues of Miscanthus is important for understanding feedstock quality for biofuel conversion and how crop residue quality may affect soil input management. Data on Miscanthus leaf and stem chemistry including carbon (C), nitrogen (N), macro- and micronutrient concentrations, and the optical characteristics of the water extractable organic matter (WEOM) was analyzed to identify differences in composition between aboveground tissues and modeled to identify soil variables that may be correlated with tissue chemistry. Leaves and stems were dominated by N, potassium (K), calcium (Ca), phosphorus (P), and magnesium (Mg), but overall, the leaves contained higher nutrient concentrations compared to the stems. The leaves displayed elevated Si:K and Ca:K ratios and lower C:N and C:P ratios compared to the stems. Leaf WEOM contained large, aromatic and complex structures while the stem WEOM was dominated by small, recently produced structures. Varying relationships were found between tissue nutrients and the soil total N and mobile C. Overall, Miscanthus leaves had a chemical composition indicative of reduced biofuel quality compared to the stems. The relationships with soil N and mobile C suggest a dynamic linkage between Miscanthus physiology and these active pools. These results have implications for crop nutrient allocation and nutrient management practices.