Ligneous-cellulosic, nitrophilous and wetland plants for biomass production and watertable protection against nutrient leaching

Research has recently stressed the importance of combining renewable energy production with environmental protection. The aim of the present work was to find new perennial herbaceous plants adequate to figure out innovative energy cropping systems based on reduced input (no tillage, use of slurry and/or wastewater for nutrient supply) and with low environmental impact. Fourteen species were cultivated in growth boxes and fertilized with pellet manure (2010-2012) and digestate (2013). Research focused on comparison of biomass production, nitrogen (N) and phosphorus (P) accumulation in aboveground biomass and the quality of percolation water. Five species, C. indica, C. pseudocyperus, G. maxima, P. arundinacea and S. sylvaticus, did not survive more than one or two years of cultivation. A. donax had the highest biomass yield, increasing yearly (26.2, 62.8, 95.1 and 140.1 Mg ha(-1), from 2010 to 2013, respectively) and significantly higher than all the other studied species. M. x giganteus production increased from the first (13.1 Mg ha(-1)) to the second year of cultivation and then remained stable (average 51.0 Mg ha(-1)); the other species showed increased productivity in the first years and then a dramatic drop in the last year. Again, A. donax had the highest nutrient accumulation in aboveground biomass, with mean yearly values of 631 kg N ha(-1) and 83.2 kg P ha(-1). The total N (TN) concentration in percolation water was higher in the first autumn-winter season, with a median close to 15 mg L-1 and great variability. Two years later, the median concentration fell to 2 mg L-1 and variability was considerably reduced. A. donax and M. giganteus turned out to be the best species in reducing nitrate N concentrations in percolation water. Concentrations of total P (TP) were two orders of magnitude lower than those of TN and showed higher and more variable values in 2012-2013 (from 0.060 to 0.145 mg L-1) than in 2010-2011 (from 0.025 to 0.034 mg L-1). The species did not significantly influence the TN and TP presence in the percolation water. Considering both biomass production and attitude to water table protection, A. donax gave the best results of all species studied.