Dilution of olive mill wastewater eliminates its phytotoxicity and enhances plant growth and soil fertility Munir

Olive Mill Wastewater (OMW) is phytotoxic and all attempts to treat it are expensive and therefore alternative less expensive techniques should be developed to reduce its phytotoxicity. The objective of this study is to determine whether the dilution of OMW with water improves its suitability for soil application and enhances plant growth without polluting the environment. The following treatments were investigated in a randomized complete block design with four replications in a greenhouse pot experiment: 1) Potable water (W); 2) Undiluted OMW (100%OMW); 3) Diluted OMW at a ratio of 1water:3omw (75%OMW); 4) Diluted OMW at a ratio of 1water:1omw (50%OMW); and 5) Diluted OMW at a ratio of 3water:1omw (25%OMW). Pots filled with 5 kg air dry soil and seeded with hybrid maize were watered periodically according to the treatments applied. At the end of the growing period, the above ground biomass was harvested and plant and soil samples were taken for chemical analysis. The results indicated that undiluted OMW reduced plant growth and increased soil salinity. Dilution of OMW reduced its phytotoxic effect, increased soil organic matter, soil N, P, and K. However, even diluted OMW increased soil salinity thus should be taken into consideration with continuous OMW application. It was concluded that the dilution of OMW (25%OMW) eliminated the OMW phytotoxicity and enhanced plant growth. Such approach can be attractive to both farmers and owners of olive mill as this approach is a practical alternative to the expensive non-affordable by the owners of mills treatments techniques