Anaerobically digested biosolid and the organic fraction from a municipal solid waste were surface applied at 80 Mg ha-1 to a degraded highly carbonated soil (Rensic Leptosol) from the southeast of Madrid (Spain) to determine the effects of these organic wastes on soil physical and chemical properties. After one year of the waste application, soil samples at 0-15 cm and 15-30 cm depths were taken. The structure of the soil was slightly improved by a small decrease in particle and bulk densities, an increase in water retention accompanied by an increase of organic matter. Waste application also increased the amorphous iron oxide contents and the total heavy metals in the soil in particular the Cu and Zn contents in the surface level. The significative increase of Zn in the subsurface level suggests that the Zn migrated in this soil profile, probably because of its affinity with organic matter soluble fractions.