LAND REHABILITATION BY URBAN REFUSE AMENDMENTS IN A SEMIARID ENVIRONMENT - EFFECT ON SOIL CHEMICAL-PROPERTIES

The constituents of urban refuse may have potential chemical benefits in reclaiming degraded soils and improving plant growth, but this may be offset by chemical problems such as increased soil salinity and the accumulation of heavy metals. A series of experiments was conducted in the Fortuna Basin in semi-arid south-east Spain on a Xeric Torriorthent to investigate changes in soil properties with urban refuse amendments varying from 6.5 to 26 kg.m-2. Soil chemical properties were monitored during three years after the application of solid, largely organic, urban refuse. Changes in the contents of potassium, phosphorus, nitrogen, organic carbon, exchangeable sodium, electrical conductivity, and the sodium, chlorine and sulphates in the saturation extract, as well as a number of heavy metals are reported. Salts are quickly leached out, whereas essential plant nutrients are retained. There is a clear medium-term benefit to soil fertility with the use of urban refuse. Potential off-site impacts of diluted toxic contaminants are discussed.