Abstract
Miscanthus is a low input energy crop suitable for low fertility marginal arable land and thought to provide carbon sequestration in soil. We analysed a long-term field experiment (14-year) to determine whether differences in genotype, growth habit, and root distribution affected soil carbon spatially under different Miscanthus genotypes. Soil cores were taken centrally and radially to a depth of 1m, and divided into six vertical segments. Total root length (TRL), root dry matter (RDM) and δ13C signature of soil organic carbon (SOC) were measured directly, and root length density (RLD), fractions of Miscanthus-derived soil organic C (SOCM), and residual soil carbon (SOCorig) were calculated. Genotype was found to exhibit a statistically significant influence on spatial allocation of SOC. Grouping varieties into ‘tuft-forming’ (T) and ‘non-tuft-forming’ (NT) phenotypes revealed that respective groups accumulated similar amounts of RDM over 14 years (11.4±3.3 vs. 11.9±4.8Mgha−1, respectively). However, phenotype T allocated more carbon to roots in the subsoil than NT (33% vs. 25%). Miscanthus genotypes sequestered between 4.2 and 7.1gC4-SOCkg−1 soil over the same period, which was more than the average loss of C3-derived SOC (3.25gkg−1). Carbon stocks in the ‘A horizon’ under Miscanthus increased by about 5Mgha−1 above the baseline, while the net increase in the subsoil was marginal. Amounts of Miscanthus root C in the subsoil were small (1.2–1.8MgCha−1) but could be important for sustainable sequestration as root density (RLD) explained a high percentage of SOCM (R2=0.66).
Highlights
Miscanthus is a favored perennial feedstock for bioenergy in subtropical and temperate regions due to its high potential productivity (Heaton et al, 2010; Lewandowski et al, 2003) and benefits with regard to the carbon and greenhouse gas balance (Dondini et al, 2009; Hillier et al, 2009)
A 3-way interaction between horizon, position and phenotype was found for root dry matter (RDM; p = 0.04), which reflects the strong contrast in spatial distributions in RDM between phenotypes
We found variation in root distribution between genotypes, with ‘T-phenotype’ allocating more biomass – relatively (33 vs. 25%) and absolutely (3.6 vs. 2.9 Mg haÀ1) – to roots at greater depth than non-tuft forming groups (NT) phenotypes
Summary
Miscanthus is a favored perennial feedstock for bioenergy in subtropical and temperate regions due to its high potential productivity (Heaton et al, 2010; Lewandowski et al, 2003) and benefits with regard to the carbon and greenhouse gas balance (Dondini et al, 2009; Hillier et al, 2009) Domestication of these perennials is in its infancy and genotypes may be found or bred that suit a wider range of ecological conditions and maximize efficiency of carbon sequestration (Clifton-Brown et al, 2008; Karp and Shield, 2008; Yan et al, 2012). Existing studies of the genotype effect focus on carbon near the surface (Zatta et al, 2014) which ignores the potentially beneficial effect of deep roots as a mechanism to sequester carbon (Kell, 2011)
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
