Root system characterization and water requirements of ten perennial herbaceous species for biomass production managed with high nitrogen and water inputs

Although several studies have investigated the aboveground production of perennial herbaceous species for biomass production, only a few details are available on their root systems and water balance. This paper provides a root system characterization and a water balance calculation for ten perennial herbaceous species (Arctium lappa L., Arundo donax L., Carex acutiformis Ehrh., Carex riparia Curtis, Glyceria maxima (Hartm.) Holmb., Helianthus tuberosus L., Iris pseudacorus L., Lythrum salicaria L., Miscanthus x giganteus Greef et Deu., Symphitum x uplandicum Nyman) cultivated with high fertilizer and water inputs in a four-year study. Crop evapotranspiration (ETc) maintained the same seasonal trend for all studied species, with the highest cumulative seasonal average water losses for A. donax (1675.1 mm) and the lowest for G. maxima (1406.0 mm). During the growing season, crop coefficients followed a similar trend to that reported for ETc, with average seasonal values ranging from 1.9 for A. lappa and G. maxima to 2.6 for M. x giganteus. For all species soil moisture was higher in the deeper soil layers (20–50 and 50–90 cm) than in the upper (0–20 cm) where a high root system biomass was observed. At the end of the study, different root system biomass productions were found between species with the highest median value at 0–50 cm depth for M. x giganteus (62.6 Mg ha−1) and the lowest for S. x uplandicum (0.5 Mg ha−1). Since these topics have not been well investigated in other studies, our initial results need to be confirmed in different climatic conditions.