Aluminium fractionation and speciation in bulk and rhizosphere of a grass soil amended with mussel shells or lime

Acid soils have a high proportion of Al in the exchange complex and are usually amended with lime to reduce the toxic effect of the free Al (Al3+). To this purpose, in some places like Galicia (NW Spain), there is a high production of wastes such as mussel shells that may substitute the lime. The aim of this work was to study the effect of different amending products derived from mussel shells on the Al chemistry in both bulk and rhizosphere, and on pasture production. The experiments were conducted on plots of an acid soil cultivated with grasses (Dactylis glomerata L., Trifolium repens L. and Lolium perenne L.). Each plot received its own treatment consisting of 1) commercial lime, 2) mussel shells dried and ground till 0–2mm (MDF), 3) mussel shells dried and ground till 2–4mm (MDC), 4) mussel shells heated (550°) and ground till