Evaluación del potencial como enmienda orgánica de un fermentado ácido-láctico de restos de alimentos

Lactic acid fermentation is presented as an alternative technique for organic waste processing, although little literature exists on the effects of applications to the soil. The aim of this work was to evaluate the evolution of different chemical and microbiological soil properties after the material’s addition.

For this purpose, a 101-day laboratory soil incubation experiment was carried up, which included two contrasting soil conditions (greenhouse soil and farm soil) and three doses of material
(0, 8.8 and 17.6 Mg. DB. ha^-1). Prior to incubation, soils and available materials were characterized. Destructive samples were taken at incubation days 7, 14, 28, 56 and 101 to determine inorganic nitrogen concentrations in the form of NO₃ and NH₄, pH_H2O and electrical conductivity. Concentrations of calcium, magnesium, potassium and sodium, as well as organic carbon and nitrogen total contents were measured at the beginning and at the end of incubation. Soil microorganism community’s indicators were evaluated, such as β-glucosidase and alkaline phosphatase activity, in addition microbial biomass estimation by counting., Soil respiration evolution was observed through a NaOH trap in a parallel incubation.

Differential behaviours were observed for evaluated soils, including NO₃ a net immobilization
of 28.4 kg N. ha^-1 in the greenhouse soil and a net mineralization NO₃ of 11.0 kg N. ha^-1 in the farm soil with fermented material applied in the same dose. In greenhouse soil, a pH_H2O increase was observed when applying the material, while in farm soil there was not. Meanwhile, the application of the material significantly increased the levels of magnesium and potassium in both soils.

No significant differences were observed for sodium levels and electrical conductivity with the adding of the fermented lactic acid in any case.

An increase in respiration in both soils was observed as a result of the application of the material, stabilizing after 76 days.