Abstract

DEL PINO, Amabelia et al. Characterization and evaluation of biosolids produced by anaerobic digestion of agroindustrial residues. Cienc. suelo [online]. 2012, vol.30, n.2, pp.151-160. ISSN 1850-2067.

The objective of this study was to characterize and evaluate the biosolids (slurry) produced in a pilot reactor feed with agroindustrial residues. The chemical characterization of the biosolids and variability estimation were conducted on slurry samples taken during five weeks. Samples were analyzed for dry matter (DM), pH, and total contents of C, N, P, K, Na, Ca, Mg, Cu, Fe, Mn, and Zn. In order to study the patterns of decomposition and nutrient release of the slurry, two soils of different textures were incubated with slurry rates equivalent to 80 and 160 kg ha-1 of N. They were compared with equal rates of fertilizer N and a check treatment without any addition. In the incubation experiment, soil respiration and nutrient release were determined during 115 days. The average DM content of the slurry was 5.2 %, pH was alkaline and the highest nutrient contents corresponded to N, P, and Ca. There was variability among samplings, although the variation coefficients were lower than 20 %. The Na and micronutrient levels were not within the range considered as environmental risk. The slurry addition promoted soilmicrobial activity. In the silt loam soil, approximately one third of the added C was lost as CO₂, and one fifth in the sandy loam soil. The slurry N was rapidly mineralized, reaching similar levels as in the fertilized soils. The addition of slurry increased the contents of available P, N, and exchangeable Ca and Mg, therefore it is concluded that it was beneficial for the soil fertility.

Keywords : Biogas; Slurry; Nutrients release; Uruguay.

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