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The changes of soil organic matter (SOM) humification induced by long-term combination of tillage and olive mill wastewater (OMW) application compared to natural and cultivated soil have been little investigated. This study aimed to compare effects of no cultivation with natural vegetation soil (NC), tillage (CT1) for 80 years and combination of tillage with OMW application (CT2) for 20 years on SOM humification degree. Fluorescence spectroscopy and UV-visible ratios (E4/E6 and CHA/CFA) were used to study soil humic acids (HAs). The SOM and humification distribution was determined for the whole field area using the Inverse Distance Weighting method. Results showed that SOM content, fluorescence emission area and E4/E6 and CHA/CFA ratios were higher in NC. Tillage reduced SOM amount, molecular size, aromatic condensation and humification degree as shown by the strong correlation between fluorescence area and CHA/CFA ratio in CT1 conversely to E4/E6. Contradictory results between fluorescence emission area and E4/E6 ratio found in NC and CT1 indicated that E4/E6 ratio was not a reliable indicator of SOM humification degree. The SOM amount, CHA/CFA ratio and emission fluorescence area increased conversely to E4/E6 ratio in CT2. This revealed a greatly humified organic matter and aromatic structure condensation with tillage and OMW application. Spatial distribution showed a progressive increase of SOM and CHA/CFA from north-west to south-east linked to the positive relationship between CHA/CFA ratio and SOM amount independent of soil management practices. Soil amended with OMW provided a favourable environment for the development of HAs which improved soil quality. The UV-visible ratio CHA/CFA with fluorescence emission area can be used as parameters to investigate SOM humification degree.

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The study of three roadsoil contamination in the Sfax region by polycyclic aromatic hydrocarbons showed a significant variation between the three sites and proportional to the distance from the road. The variation between the physicochemical characteristics of three soils influenced the spatial distribution of polycyclic aromatic hydroacarbons. Quantitatively, the soils near Manzel Chaker road had the highest content followed by those of the Tunis road soil . Qualitatively, chrysene, benzo (b) fluorenthene;benzo (a) anthracene and Indeno (1.2.3.cd) pyrene were the most abundant compounds. These contaminants, with naphthalene and fluorenthene, affected the germination and aerial growth of tomato but with no significant effect on the germination and growth of cucumber which has shown resistance to pollution by polycylic aromatic hydrocarbons. The use of PCA and regression between parameters indicated that these compounds which are in mixture in soil have disturbed the germinative capacity, the speed of germination and the aerial elongation of tomato. In the same soils, the cucumber showed resistance to this contamination and its germination was not affected.

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