Proposed Soil Indicators for Olive Mill Waste (OMW) Disposal Areas

The disposal of olive mill wastes (OMW) is considered as a major environmental problem worldwide, but especially for Mediterranean countries. Disposal in evaporation ponds or directly on soil is a common practice, which causes serious damages to soil and to the environment. The present study was performed in the framework of the LIFE project Strategies to improve and protect soil quality from the disposal of Olive Mill Wastes in the Mediterranean region-PROSODOL and one of its main objectives was the identification of appropriate soil parameters that could be used as soil indicators to assess soil quality at OMW disposal areas. For this, a well-designed soil sampling strategy was developed and implemented in Crete, South Greece at five OMW disposal areas. Many soil parameters were monitored bimonthly for a year. After statistical evaluation, eight soil parameters were selected as being appropriate soil indicators for OMW disposal areas, i.e., electrical conductivity, pH, organic matter, polyphenols, total N, exchangeable K, available P, and available Fe. Although many researchers have extensively studied the effect of OMW on soil quality, yet the identification of soil indicators to assess and monitor soil quality is an innovative issue and has never been studied before.