Effects of some organic fertilizers on olive oil yield and quality under mardin conditions

This study evaluated the effects of different organic fertilisation regimes on olive oil quality parameters in Gemlik olive cultivar olive groves of Deyrulzafaran Monastery in Mardin province. The dose responses of pomace (P1: 4 kg/tree, P2: 8 kg/tree, P3: 12 kg/tree), leonardite (L1: 1.5 kg/tree, L2: 3 kg/tree, L3: 4.5 kg/tree) and vermicompost (SG1: 3 kg/tree, SG2: 6 kg/tree, SG3: 9 kg/tree) applications were examined and evaluated in terms of sustainable agricultural practice. The soil of the research area has a slightly alkaline character and loamy structure; it does not pose a problem in terms of salt content. As a result of the two-year study, soil organic matter content was determined as 1.98% at 0-30 cm depth and 1.30% at 30-60 cm depth. Organic matter content of P3, L3, SG1 and SG3 treatments were higher than the general average especially at 0-30 cm depth, while L1, L2 and SG1 treatments were higher than the general average at 30-60 cm depth. Free acidity (% oleic acid) content varied between 0.27% and 0.42%, the highest value (0.42%) was found in L2 treatment, while the lowest values (0.27%) were obtained in P2 and P3, L3 and SG2 treatments in statistically similar groups. The average total phenolic content was 307.115 mg/L and P2, L1, SG3, SG3, KG and P3 treatments exceeded the average of the experiment. The results obtained indicate that the current approach to olive oil quality assessment centred on acid level should be extended to other important parameters such as phenolic profile and values. This study provides strong evidence in favour of revising the Turkish Food Codex Communiqué on Olive Oil and Olive Pomace Oil.