Compost Use in Agriculture: The Fate of Heavy Metals in Soil and Fodder Crop Plants

The effects of organic fertilizer application on heavy metals accumulation in both soil and plants and on the main soil fertility parameters have been evaluated in a long-term field experiment. The research was carried out in a Mediterranean environment (Rutigliano, Southern Italy – 41° 01′ latitude N, 4° 39′ longitude E, 112 m a.s.l.) since the autumn of 2001 in permanent rain-fed meadows of alfalfa (Medicago sativa L.) and cocksfoot (Dactylis glomerata L.). Two organic materials, Municipal Solid Waste (MSW) compost and Olive Pomace (OPC) compost, were compared to nitrogen (cocksfoot) and phosphorus (alfalfa) mineral fertilizer treatments. The results showed that at the end of the first four years, the MSW and OPC composts application did not cause any heavy metals accumulation in soil and plants. Only the Zn reached a high level in the cocksfoot experimental soils. In addition, these organic materials allowed significant increases of extracted and humified soil organic carbon in the plots of both fodder...