Metal, nutrient and biomass accumulation during the growing cycle of Miscanthus established on metal-contaminated soils Florien Nsanganwimana 1,2 , Christophe Waterlot 1 , Brice Louvel 1 , Bertrand Pourrut 1 , and Francis Douay 1 * 1 Laboratoire Ge´ nie Civil et ge´oEnvironnement (LGCgE), ISA Lille, 48 boulevard Vauban, 59046 Lille Cedex, France 2 University of Rwanda-College of Education, Remera Campus, KG 11 Avenue 47, P.O. Box 5039, Kigali, Rwanda Abstract The energy crop Miscanthus presents high potentials for phytomanagement. Its shoot yield and nutrient accumulation has been extensively characterized in uncontaminated agricultural soils, while very little is known for metal-contaminated conditions. This study aimed at assessing potential differences in dry matter and metal and nutrient accumulation of the standing aerial bio- mass in Miscanthus (M. · giganteus) growing in situ on agricultural plots presenting different soil Cd, Pb, and Zn concentrations. Plant samplings were conducted monthly along the growing peri- od from May to December. Cadmium, Pb, Zn, and the concentrations of the nutrients N, P, K, Ca, Mg, and Na were determined in leaves and stems separately. During the growing phase, the maximum dry matter was reached in early in autumn. Whatever the organ, Cd and Zn concentra- tions were higher on contaminated than on uncontaminated plots. During summer and autumn, Zn and Pb concentrations were higher in leaves than in stems whereas Cd concentrations did not significantly differ between the organs. Concentrations of N, P, K, and Mg decreased across the study period whereas those of Ca and Na increased. Overall, metal and nutrient concentra- tions depended on plant organ and its development stage. The dry matter and nutrient accumu- lation patterns were not different between contaminated and uncontaminated plots. The signifi- cance of these findings is discussed in light of best phytomanagement practices and potential uses of Miscanthus biomass. Key words: Miscanthus · giganteus / biomass / phytomanagement / growing season / senescence Accepted October 03, 2015 1 Introduction Worldwide, large surface of land are reported to be contami- nated by metals (Evangelou et al., 2012; Panagos et al., 2013). Soils on such lands require appropriate management and remediation options to avoid loss of arable surface areas and to produce economically valuable biomass, while alleviat- ing metal exposure and associated environmental/health risks (Evangelou et al., 2012; Witters et al., 2012). Due to its high productivity, its tolerance to abiotic and biotic stresses, and its biomass with multiple uses, the perennial grass Mis- canthus (Miscanthus · giganteus) is considered as a suitable candidate plant to couple management of metal-contami- nated lands and biomass production (Nsanganwimana et al., 2014). Moreover, Miscanthus is characterized by a high nu- trient use efficiency and a high nutrient turnover in soils as a result of nutrient translocation and mulch decomposition, hence little requirements for mineral fertilization (Cadoux et al., 2014; Nassi o Di Nasso et al., 2011). To maintain local farmer’s activities, the cultivation of Miscan- thus was proposed as a sustainable management option of metal-contaminated agricultural soils within Metaleurop site located in N France (http://www.safir-network.com/site- de-metaleurop/). This site covers a large surface (about 120 km 2 ), mainly contaminated by atmospheric emissions of the former lead smelter called Metaleurop Nord. This smelter had released large quantities of metal (mainly Cd, Pb, and Zn)-contaminated dust for more than a century until its clo- sure in 2003 (Douay et al., 2008). This has resulted in a high soil contamination. After its closure, most of the crops grown on these soils still present Cd, Pb and Zn concentrations which are higher than the maximum threshold allowed for food and feed (Douay et al., 2013; Pruvot et al., 2006). Exper- imental Miscanthus plantations were established since 2007 to evaluate the phytostabilization potential of this plant com- bining the production of energy-dedicated biomass on conta- minated soils and limitation of environmental and human risks on the Metaleurop site. Studies of the metal concentrations in Miscanthus above- ground biomass from contaminated soils have only focused on late harvest but not on the metal composition in the stand- ing biomass across the growth cycle (Barbu et al., 2013; Pogrzeba et al., 2013). High Zn concentrations are usually found in shoots regardless of the degree of soil contamination (Nsanganwimana et al., 2014), and for Cd and Pb in case of highly contaminated soils (Kocon´ and Matyka, 2012; Pogrzeba et al., 2013). However, none of the above-men- tioned studies covered the entire Miscanthus growing cycle ª 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim www.plant-soil.com J. Plant Nutr. Soil Sci. 2016, 179, 257–269 DOI: 10.1002/jpln.201500163 257 *Correspondence: Dr. F. Douay; e-mail: francis.douay@isa-lille.fr