Biomass production and nutrient removal from perennial energy grasses on a wet marginal land

Authors: COONEY, DANIELLE - University Of Illinois; NAMOI, NICTOR - University Of Illinois; ZUMPF, COLLEEN - University Of Illinois; LIM, SOOHYUN - University Of Illinois; VILLAMIL, MARIA - University Of Illinois; Mitchell, Robert - Rob; LEE, DOKYOUNG - University Of Illinois

Submitted to: BioEnergy Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/11/2022
Publication Date: 7/23/2022
Citation: Cooney, D., Namoi, N., Zumpf, C., Lim, S., Villamil, M., Mitchell, R., Lee, D. 2022. Biomass production and nutrient removal from perennial energy grasses on a wet marginal land. BioEnergy Research. https://doi.org/10.1007/s12155-022-10488-0.
DOI: https://doi.org/10.1007/s12155-022-10488-0

Interpretive Summary: Dedicated energy crops have been targeted for marginal land to grow biomass, provide ecosystem services, and potentially remove nutrients from wet soils to reduce downstream implications. This two-year study evaluated the relationship between management and nutrient recovery on wet marginal land in a high priority nutrient loss reduction zone in Illinois. Four perennial grass treatments including (1) Switchgrass, (2) Miscanthus x giganteus (MG), (3) Prairie cordgrass, and (4) a mixture of big bluestem, Indiangrass, and sideoats grama, were evaluated for biomass production, nutrient uptake, and nutrient removal under two harvests (growing season and after frost) and three N fertilizer rates. Biomass yields were significantly higher across grasses N rates, with the exception of MG when harvest during the growing season. This also corresponded with higher tissue nutrient concentrations and nutrient removal across N-rates during growing season harvest. Switchgrass had the highest N removal potential across all N-rates at both harvests, while MG had the greatest P and K removal when harvested after frost. Increasing N rate correlated with increased biomass and nutrient removal across most treatment combinations. Our results suggest switchgrass is the optimal species for both biomass production and nutrient removal when harvested during the growing season. Additionally, our results demonstrate producers have flexibility in choosing a system that works for them and would still allow for nutrient removal, but harvesting after frost is best suited to preserve the longevity of the stands while maintaining nutrient removal. MG had the highest biomass yield potential while the mixture had little change in yield based on harvest timing, suggesting better yield stability. Future studies should evaluate mixture over the long-term to assess their biomass yields and nutrient removal capacities.

Technical Abstract: Growing dedicated bioenergy crops on marginal land can provide beneficial outcomes including biomass production and energy, resource management and ecosystem services. Various management strategies can be utilized for perennial grass production depending on the desired outcome of the grower. There is increasing interest in understanding the potential nutrient recovery that can accompany the various management strategies for downstream implications related to nutrient movement. This two-year study aimed to understand the relationship between management and nutrient recovery by evaluating biomass production on wet marginal land located in a high priority nutrient loss reduction zone in Illinois. Four perennial grass treatments including (1) Switchgrass [Panicum virgatum L. – SW], (2) Miscanthus x giganteus – MG, (3) Prairie cordgrass [Spartina pectinata Link – PCG], and (4) a polyculture mixture of Big bluestem [Andropogon gerardii Vitman], Indiangrass [Sorghastrum nutans (L.) Nash], and sideoats grama [Bouteloua curtipendula {Michx.} Torr. – MIX], were evaluated for biomass production, nutrient uptake, and nutrient removal under two harvest timings (peak standing crop [PEAK] and after killing frost [KF]) and three nitrogen (N) fertilizer rates (0, 56 and 112 kg N ha-1). Biomass yields were significantly higher across grass treatments and N rates, with the exception of MG when harvest occurred at PEAK timing. This also corresponded with significantly higher tissue nutrient concentrations and nutrient removal (a function of biomass and concentration) across N-rates at PEAK harvest. Switchgrass had the highest N removal potential across all N-rates at PEAK and KF harvest timings, while MG exhibited the most significant removal of P and K at KF. Increasing the application of N did correlate with increased biomass, concentration and subsequent removal of nutrients across almost all treatment combinations. Our results suggest that SW could be an optimal species for both biomass production and nutrient removal when harvested at peak standing crop. Our data suggests that on a short-term basis, producers have plasticity in choosing a system that works for them and would still allow for nutrient removal. However, these results of a young stand also suggest a KF harvest management system is best suited to preserve the longevity of the crop while still maintaining adequate nutrient removal. In this study, MG exhibited the highest biomass yield potential under this system. An additional insight from this study found the polyculture treatment exhibited little change in yield based on harvest timing, suggesting better yield stability. Future studies should give consideration for long-term evaluation of polyculture mixtures to assess their biomass yields and nutrient removal capacities.