Soil water uptake and root distribution of different perennial and annual bioenergy crops
2015
Ferchaud, Fabien | Vitte, Guillaume | Bornet, Frédéric | Strullu, Loic | Mary, Bruno | Agroressources et Impacts environnementaux (AgroImpact) ; Institut National de la Recherche Agronomique (INRA) | French National Research Agency (ANR) under the project "Regix" ; BPI-France under the project "Futurol"
Bioenergy crops are expected to provide biomass as a replacement for fossil resources, but their impact on the water cycle is still under question. This study aimed at both quantifying the ability of bioenergy crops to use soil water and analysing the relationship between their root systems and soil water uptake. Water content was monitored continuously for 7 years (2007-2013) under perennial (Miscanthus x giganteus and Panicum virgatum), semi-perennial (Festuca arundinacea and Medicago sativa) and annual (Sorghum bicolor and x Triticosecale) bioenergy crops. Root distribution was characterized in 2010 down to 3 m depth. Soil water deficit (SWD) was calculated as the difference between field capacity and actual water content. Maximal SWD (0-210 cm) during the growing season was higher for semi-perennials, despite a lower biomass production than perennials. Water capture in deep soil layers was greater under perennials and semi-perennials than under annual crops. A curvilinear asymptotic relationship was found between water capture and root density and described by a model the parameters of which varied between crops, indicating a variable soil water capture for a given root density. This study provides quantitative information required to simulate the impact of bioenergy crops on drainage and aquifer loading.
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