In this study the leaching properties of Pinus halepensis (Aleppo pine) needles ash before and after treatment with DAP have been investigated by shake leaching tests. For the analysis of ashes (prior and after leaching) and leachants a variety of analytical techniques were employed, including atomic emission spectroscopy with inductively coupled plasma (ICP-AES), ion chromatography (IC), X-ray diffraction (XRD) and scanning electron microscopy (SEM). The presence of DAP obstructs the extraction process of metals contained in ashes, probably of the non-soluble phosphates compounds formed, causing unfavourable effects to soil and plants.