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Providing evidence to improve practice

Individual study: Effects of sewage sludge amendment on humic acids and microbiological properties of a semiarid Mediterranean soil

Published source details

García-Gil J.C., Plaza C., Senesi N., Brunetti G. & Polo A. (2004) Effects of sewage sludge amendment on humic acids and microbiological properties of a semiarid Mediterranean soil. Biology and Fertility of Soils, 39, 320-328


This study is summarised as evidence for the intervention(s) shown on the right. The icon shows which synopsis it is relevant to.

Soil: Add sewage sludge to the soil Mediterranean Farmland

A replicated, controlled study in 2004 in a barley field in Spain found more carbon dioxide in soils with added sewage sludge, compared to soils without it. Soil organisms: Similar amounts of microbial biomass (measured as carbon) were found in soils with or without added sewage sludge (179–229 vs 174 mg/kg). Greenhouse gases: Higher rates of respiration (measured as carbon dioxide) were found in soils with added sewage sludge, compared to soils without it, in one of two comparisons (50 vs 15 µg CO2/g/day). Methods: Sewage sludge (40 t/ha) was added to some plots, but not to others (plot size and number of replicates not reported). Soil samples (0–20 cm depth) were taken from each plot, nine and 36 months after adding the sewage sludge.