A green house experiment was conducted to investigate the effects of the application of solid urban waste compost at a rate of 30 g dm-3 (60 t ha-1), on 21 acid and five alkaline soils in relation to their organic carbon, total nitrogen, available phosphorous and sulfur contents. Compost from the São Matheus Treatment Plant (São Paulo, Brazil) was applied with or without dolomitic lime and mineral fertilizers. In alkaline soils, lime was substituted by gypsum. The experiment was carried out with soils in the plots, in a completely randomized block design with three replicates, and treatments in the sub-plots. Compost application caused evident organic carbon accumulation in soils with initial organic carbon contents > 12 g dm-3 and nitrogen > 1.3 g dm-3, but a C/N ratio < 12. In the other soils, organic carbon accumulation was a consequence of the interaction between the stability of compost organic matter, original organic matter, and physical and chemical soil properties. Residue application increased the contents of total nitrogen and available sulfur in all soils, but available phosphorous only increased in acid soils. The use of solid urban waste compost as organic fertilizer in agricultural areas is viable under the condition, however, that its effects on chemical properties are properly monitored.
organic fertilization; nutrient availability; soil organic matter; nutrient mineralization and immobilization