Improving the mining soil quality for a vegetation cover after addition of sewage sludges: Inorganic ions and low-molecular-weight organic acids in the soil solution

Abstract

We assessed the effects of applying stabilized sewage sludge (SSL) and composted sewage sludge (CLV), at 5 and 10% to an acid mining soil. Limed soil (NCL) amended or not with SSL and CLV was incubated for 47 days. We studied the cations and organic and inorganic anions in the soil solution by means of ion chromatography. Liming led to big increases in Ca2+ and SO42- and to significant decreases in K+, Mg2+, NH4+ and NO3-. Addition of both organic amendments increased some cations (NH4+, K+, Mg2+, Na+) and anions (Cl-, NO3- only with CLV and PO43- only with SSL) and provided a greater amount of low-molecular-weight organic acids (LMWOAs) (SSL more than CLV). Incubation led to decreases in all cations, particularly remarkable for Ca2+ and Mg2+ in SSL-10. A decrease in NH4+ was associated with variations in NO2- and NO3- resulting from nitrification reactions. During incubation the LMWOAs content tended to decrease similarly to the cations, especially in SSL-10. Chemometric tools revealed a clear discrimination between SSL, CLV and NCL. Furthermore, treatment effects depended upon dose, mainly in SSL. Amendment nature and dose affect the quality of a mining soil and improve conditions for plant establishment.