Evaluation of the influence of olive mill waste on soils: the case study of disposal areas in Crete, Greece

It is well known that soils where olive mill wastes (OMWs) are disposed of eventually become overloaded with organic matter unknown and insufficient quality as inorganic nutrients polyphenols. In European Mediterranean countries, the disposal OMW considered to be a major environmental issue. An extensive study on risks soil caused by OMW, in framework LIFE PROSODOL Project (http://www.prosodol.gr), resulted definition eight indicators. The indicators specifically for contain pH, matter, electrical conductivity, total nitrogen, polyphenols, exchangeable potassium, available phosphorus, iron. To confirm validity this set indicators, nine areas were randomly selected studied Rethymno, Crete, without any knowledge their history, details production disposal, or other activities those areas. Soil samples collected analyzed particle size distribution, carbonates, N, P, cations (K, Ca, Mg), boron, Mn, Fe, Cu, Zn. results indicated all parameters affected but different directions magnitudes. Changes evaluated considering number ponds which (a) changes observed; (b) parameter value was measured above excessive threshold; (c) change values >100%. revealed iron constituents three evaluation factors yielded highest values. Moreover, zinc could also potential indicator although it not included With regard pH no substantial observed study, they should always valuable evaluating buffering capacity salinization threat, respectively.