Sewage sludge effects on carbon dioxide-carbon production from a desurfaced soil

Desurfaced soils are found near cities in the Pampean Region of Argentina because A horizons were used for brick production. These soils are not suitable for agriculture. Application of sewage sludge is a tool for improving soil productivity, but its effects on the environment are not thoroughly understood. Production of carbon dioxide (CO(2))-carbon (C) in the field from a desurfaced soil in which 25 Mg dry matter ha(-1) of sewage sludge were applied the first year and 10 Mg dry matter ha(-1), the second year was evaluated during a corn (Zea mays L.) growing cycle. Microbial biomass and metabolic activity were also measured. Sludge applications produced an increase of the CO(2)-C efflux in the field of 30-50% during summer. Microbial biomass was not affected by sludge some months after the application, but metabolic activity and organic matter mineralization were enhanced. The increase of the CO(2)-C emission from the soil represented 21% of the sludge C applied the year of the experiment and 15% of the C applied the year before. Consequently, an important quantity of the sludge C was retained in the soil.