Characterization of fine root system and potential contribution to soil organic carbon of six perennial bioenergy crops

• Published in: Biomass & bioenergy 2015-12, Vol.83, p.116-122
• Main Authors: Chimento, Carlo, Amaducci, Stefano
• Format: Article
• Language: English
• Subjects: C sequestration; Fine root biomass; Perennial bioenergy crops; Root diameter; Root length density; Root vertical distribution
• ISSN: 0961-9534; 1873-2909
• DOI: 10.1016/j.biombioe.2015.09.008

Perennial bioenergy crops provide biomass for renewable energy production, but also sequester atmospheric carbon (C) in the soil. Roots represent one of the most important soil C inputs-root length density (RLD, cm cm−3), root diameter and fine root biomass (FRB, Mg ha−1) in the top 1 m of soil were characterized for three woody (poplar, black locust, willow) and three herbaceous (giant reed, miscanthus, switchgrass) perennial crops in the same location. The vertical distribution of FRB and RLD was described by fitting the “beta” (β) model to the experimental data. The herbaceous species had higher β values for FRB and RLD than woody crops, suggesting that the former explore the deeper soil layers with a greater proportion of roots. In particular, 3.7 Mg ha−1, or 43% of the whole root mass, was found below the ploughing soil layer (0.3 m) for the herbaceous species, while only 1.2 Mg ha−1, or 26% of the whole root mass, was allocated by woody crops to the same soil layer. In all the species, the majority of the sampled roots (99.1%) had a diameter lower than 2 mm, and in the first 10 cm of the soil the woody species tended to produce roots with a smaller diameter than those of the herbaceous species. Overall, the herbaceous crops have a higher potential to contribute to C storage in the deep soil layers, while the woody species, have a greater potential to affect soil organic carbon in the top soil layer. •Fine roots of six perennial bioenergy-crops in a single experiment are described.•The root length, biomass and diameter were measured.•Herbaceous species accumulate a large fraction of fine root biomass at deep soil layers.•Woody species showed a more superficial root system with thinner roots.