Chemical and biological properties of a sandy loam soil amended with olive mill waste, solid or liquid form, in vitro

Background: The profitable use of the large amounts of olive oil mill wastes produced in Greece, as source of soilorganic matter, might be probably beneficial to soil microorganism activity.Results: A high rate of organic matter biodegradation was observed in soil samples amended with the liquid formof olive mill wastewater, whereas the vice versa results were obtained with the solid form. When the soil wasamended with a mixture of both olive mill waste forms, liquid (L) and solid (S), the organic matter of the solidwaste (S) showed a well-improved biodegradation; the available forms of P, K, Zn, Mn, and Cu were increased,especially in treatments where the olive mill wastewater, liquid form, was threefold in comparison to the solid form.Moreover, the soil amended with the solid (S) form of olive mill waste reduced bacterial growth significantly, andboth waste forms act negative impacts to soil-borne fungi belonging to the genus Rhizopus.Conclusions: The results of this work demonstrated the high potential of olive mill waste, solid or liquid form,added to sandy loam soil in an incubation experiment in vitro. The better results for soil quality were obtainedwhen a combining mixture of these materials was added in the ratio 1:3 (solid/liquid).

Keywords:

Olive mill waste , Soil organic matter biodegradation , Soil microflora , Soil chemical properties