Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
2415044 | Agriculture, Ecosystems & Environment | 2009 | 8 Pages |
This study focused on root size and distribution of energy crops which may be a reliable indicator of the capability of these crops to accumulate significant C stocks in the soil. Alike, understanding root size and distribution may provide new insights into the knowledge of mechanisms involved in soil water uptake. The present research was performed in North Italy, Po Valley (32 m a.s.l., 44°33′N, 11°21′E). The assessment of root distribution and biomass of Panicum virgatum (switchgrass = S), Miscanthus x giganteus (miscanthus = M), Arundo donax (giant reed = G) and Sorghum bicolor (fibre sorghum = FS), in a soil profile of 1.2 m depth, aimed at providing new insights into carbon storage and water capture capacity. Despite a similar above ground biomass production, perennial crops exhibited different total root biomass, root shape and water uptake. G accumulated considerably higher total root biomass (13.6 Mg ha−1, d.w. basis), while FS, being annual, produced clearly the lowest root biomass (2.1 Mg ha−1). Root biomass distribution was described using the β model, through the relationships between root length density (RLD) and soil depth. In summary, M had a very superficial root shape (β = 0.931) with almost 90% of total root biomass concentrated in the top 0.35 m soil, while G and S exhibited a relative even root distribution (β = 0.979 and 0.984, respectively). RLD and root weight showed diverse patterns among crops and along the soil profile due to different root diameters and root bulk densities of the crops. Root water capture capacity (ϕ) was determined according to the King model through the relationship between soil moisture and RLD in vertically succeeding soil layers. Differences in ϕ among crops were expressed through the constant k, which resumes many physiological and environmental details driving water uptake. Briefly, high k means a faster water uptake for a given RLD. M showed the highest k (2.50) followed by FS (1.02), G (0.54) and S (0.31). Importantly, k and β were closely and negatively related which would mean that top-rooted crops, though being more subjected to drought risks, have significant higher abilities in recovering soil water. This is an assertion which is consistent with the previous studies that showed M being highly productive under wet environment, but very sensitive to water shortage. This study shows that energy crops can greatly differ in terms of water capture and root distribution, a fact that should be taken into great account in optimizing the land use change.