Ecosystem‐scale biogeochemical fluxes from three bioenergy crop candidates: How energy sorghum compares to maize and miscanthus. Issue 3 (22nd December 2020)

• Record Type: Journal Article
• Authors: Moore, Caitlin E.; von Haden, Adam C.; Burnham, Mark B.; Kantola, Ilsa B.; Gibson, Christy D.; Blakely, Bethany J.; Dracup, Evan C.; Masters, Michael D.; Yang, Wendy H.; DeLucia, Evan H.; Bernacchi, Carl J.
• Is Part Of: Global change biology. Volume 13:Issue 3(2021)
• Page Start: 445
• Page End: 458
• Publication Date: 2020-12-22
• Subjects: bioenergy cropping systems -- carbon -- eddy covariance -- light use efficiency -- nitrogen -- water use efficiency; Biomass energy -- Periodicals; Biomass energy -- Environmental aspects -- Periodicals; Energy crops -- Periodicals; 662.88
• DOI: 10.1111/gcbb.12788
• Languages: English
• ISSNs: 1757-1693

Abstract

Abstract: Perennial crops have been the focus of bioenergy research and development for their sustainability benefits associated with high soil carbon (C) and reduced nitrogen (N) requirements. However, perennial crops mature over several years and their sustainability benefits can be negated through land reversion. A photoperiod‐sensitive energy sorghum ( Sorghum bicolor ) may provide an annual crop alternative more ecologically sustainable than maize ( Zea mays ) that can more easily integrate into crop rotations than perennials, such as miscanthus ( Miscanthus × giganteus ). This study presents an ecosystem‐scale comparison of C, N, water and energy fluxes from energy sorghum, maize and miscanthus during a typical growing season in the Midwest United States. Gross primary productivity (GPP) was highest for maize during the peak growing season at 21.83 g C m −2 day −1, followed by energy sorghum (17.04 g C m −2 day −1 ) and miscanthus (15.57 g C m −2 day −1 ). Maize also had the highest peak growing season evapotranspiration at 5.39 mm day −1, with energy sorghum and miscanthus at 3.81 and 3.61 mm day −1, respectively. Energy sorghum was the most efficient water user (WUE), while maize and miscanthus were comparatively similar (3.04, 1.75 and 1.89 g C mm −1 H2 O, respectively). Maize albedo was lower than energy sorghum and miscanthus (0.19, 0.26 and 0.24, respectively), but energy sorghum had a Bowen ratio closer to maize than miscanthus (0.12, 0.13 and 0.21, respectively). Nitrous oxide (N2 O) flux was higher from maize and energy sorghum (8.86 and 12.04 kg N ha −1, respectively) compared with miscanthus (0.51 kg N ha −1 ), indicative of their different agronomic management. These results are an important first look at how energy sorghum compares to maize and miscanthus grown in the Midwest United States. This quantitative assessment is a critical component for calibrating biogeochemical and ecological models used to forecast bioenergy crop growth, productivity and sustainability. Abstract : Energy sorghum, maize and miscanthus are three crop candidates primed to contribute to bioenergy production in the United States. We showed that while energy sorghum is an annual crop much like maize in it's nitrogen fluxes, it behaves more like the perennial crop miscanthus in terms of its carbon capture per volume of water and mega joule of light used. Our assessment provides an important first step toward quantifying ecosystem scale biogeochemical fluxes between these three cropping systems that is required to assess their long‐term ecological sustainability.