Olive Mill Wastewater for Degraded Soil Restoration

Abstract

In Southern Tunisian arid regions, the main issues of soil degradation on the surface by wind erosion (loss of nutrients and organic matter) and in depth by reduction of water reserves were diagnosed. In order to preserve these soils, improve biological activity and maintain their productivity, a restitution of organic amendments becomes necessary. Among the remedial solutions, the composting of olive tree by-products (Olive Mill Wastewater (OMW), Ramial Chipped Wood (RCW)) could be used for these soils. In this context, an experiment in pots was carried out on Medicago sativa L. in order to evaluate the effects of compost on ecosystem services of a sandy soil sampled from an experimental olive orchard in Chammakh. Two treatments (OMW with RCW and RCW) were applied and compared to a control soil having a sandy texture, with %sand being at least equal to 80%. The results showed that the highest nitrogen content is recorded with the composite compost (OMW with RCW) (0.26 g kg-1). The Electric Conductivity of treated soil decreased by 60% over time. The RCW was the most effective treatment for improving soil phosphorus properties and above-ground biomass. The OMW combined with RCW compost allowed to keep almost the same soil moisture (147.23 g kg-1) but almost 3 times more compared to a control soil (52.30 g kg-1).