Long term effects of olive mill wastewaters application on soil properties and phenolic compounds migration under arid climate

Results have showed that the irrigation of sandy soils by different doses of OMWW has influenced the soil physicochemical and microbiological characteristics. However, a slight change in the granulometric composition of soil treated with OMWW has been distinguished. The study of the phenolic compounds dynamic has showed the migration of these compounds further than 120 cm soil depth. The comparison of the different spectra obtained by the high pressure liquid chromatography (HPLC) technique has explained that the high molecular weight polyphenols which have been retained in the upper soil layers. However, the low molecular weight phenolic compounds have been detected in depth. All the results obtained have proved that the dose of 50 m3 ha−1 has been the most suitable for the soil studied.