Abstract

SANDOVAL-ESTRADA, Marco; CELIS-HIDALGO, José; STOLPE-LAU, Neil  and  CAPULIN-GRANDE, Juan. Effect of sewage sludge and salmon wastes amendments on the structure of an Entisol and Alfisol in Chile. Agrociencia [online]. 2010, vol.44, n.5, pp.503-515. ISSN 2521-9766.

In Chile the generation of sewage sludge increased from 200 t d^-1 in 1990 to 300 t d^-1 in 2010, while the salmon industry increased its production from 50 000 t annually in 1990 to 397 000 t in 2007 and generated 1.4 t of sludge per t of salmon produced. In addition, these organic wastes are applied to the soil without analyzing their effects on physical properties. This study analyzed the effects of amendments with urban and salmon sludge in the distribution and stability of aggregates (mean weight diameter, DPM) in a degraded Entisol and Alfisol soil. The treatments were: sewage sludge (LU), land- farmed salmon sludge (LP), lake-salmon sludge (LL), at doses of 25, 50, 75, 100 and 150 t ha^-1, and an absolute control (TS), not amended. There were two additional treatments with ryegrass (Lolium multiflorum L.): soil without sludge (TC) and soil with inorganic fertilizer (FN). The experimental design was completely randomized with three replicates, and Tukey test (p<0.05) was used to compare means. After six months there were significant differences (p<0.05) between the doses used in the two types of degraded soils. In the Entisol, amendments at 100 and 150 t ha^-1 increased the amount of macroaggregates (>0.25 mm) for LU (64.15%) and LP (66.7% ), and led to a better DPM (p<0.05), as compared to TS, TC and FN, whereas LL showed no significant differences. In the Alfisol, with LU the amount of macroaggregates (>0.25 mm) was greater at doses of 100 (34.1%) and 150 t ha^-1 (33.0%), whereas with the doses 100 and 150 t ha^-1 LU, LP and LL showed higher values of DPM than the absolute control (p<0.05).

Keywords : Lolium multiflorum; biosolids; stability of aggregates; macroaggregates; soil remediation.