The Use of River Sediments for Plant Nursery in the Framework of the LIFE+ project CLEANSED

-- River sediments are an integral and dynamic part of river basins but where human activities interfere with sediment quantity or quality, their management becomes necessary. Dredging and especially stocking polluted sediments is highly expensive, therefore it would be valuable to find ways to make them a reusable product instead of throwing to landfill. On the other side, there are productive field activities demanding high quantity of soil, such as plant nursing. A European estimation calculates that every year plant nursing consumes about 5.2·106 m3 of soil. To address these issues, five Institutions from Italy and one from Spain are involved in the CLEANSED project (LIFE12 ENV/IT/00652, 2013-2016). One of the aims of the project is to test the use river sediments as plant growing substrates after being decontaminated through phytoremediation technologies. After phytoremediation process, the sediments are experimented as amendant in soil used for plant nursing: the substrate has to guarantee root development but also soil cohesion of root balls when the plants are extracted for sale. The experimental plan aims to test substrates with different percentage of sediments and alluvial soil in order to identify the mixture which guarantees the best plant quality. From May 2014 to November 2015, three ornamental bush species (Photinia x fraseri var. Red Robin, Viburnum tinus L. and Eleagnus macrophylla L.) were planted into woody frames filled with different percentage of sediments and soil (respectively 0 and 100%, 33% and 66% and 50% and 50%). Physical and chemical properties of the substrates as well as plant growth, physiological behavior and stress signals have been monitored through 2014 and 2015 vegetative season. The aim of this study is to present the setting and some results about plant growth, with a focus on the effect of temperature and substrate on the growth of the investigated species..