Characterisation of clays from Alicante province (SE Spain) for use in the recovery of degraded soils.

The goal of this paper is the characterisation of seven clays of the province of Alicante (SE Spain) and their possible use to improve the fertility, water absorption and contaminant-retaining capacity of degraded soils. Three soils affected by the dumping of construction debris were also studied to diagnose the problems and possible recovery strategies. Several physicochemical properties were measured, such as the water holding capacity, soil organic matter, lime, pH, EC and CEC. A high correlationship between mineralogical and elemental composition was obtained. Illite was present in all clays and soils. Some of the samples also contained kaolinite and significant amounts of lime. The CEC, as expected, was more closely related to the organic matter content. Soil organic matter was detected in the second derivative of the FTIR spectra by the signals of the CH2 groups at 2850 and 2919. This way, the FTIR spectrum for the soils of the area would make it possible to estimate both the organic matter content and the CEC. Despite their origin, soils did not show heavy metal pollution; however, salinisation risk seemed to be the most probable cause of degradation. According to the organic matter, lime and illite content, two clays were selected as the most suitable for soil degradation recovery. Furthermore, organic matter additions may help to improve the self-depurative ability of the soil.