Effect of olive mill pomace compost on yield, oil percentage and the leaf elements content in two olive cvs ’Zard’ and ’Roughany’

Background: The use of olive mill solid waste to form of compost in olive groves, in addition to helping dispose of this by-product of the olive oil industry, also can recycles nutrients that out of the garden during the fruit harvest. The aim of this study, was to riplacing of this compost with manure of animal at the olive groves as an organic fertilizer, improvement on the nutritional status of olive trees, fruit quality, fruit yield and oil.
Materials and Methods: Olive mill waste solid was mixed with 10% wheat straw (W/W) and two percent urea. The composting process was completed after three months. 12, 24 and 36 kg olive pumice compost was given per tree. Control trees donʹt received compost (first control) or 15 kg of manure (second control) instead of compost. The fruit yield, oil yield, fruit quality characteristics and leaf mineral elements content of ‘Zard’ and ‘Roughany’ olive cultivars were evaluated in compost treated and control over two years.
Results: The most both fruit and oil yield in the first and second year after treatment belonged to the 12 and 36 kg compost treatment in ‘Zard’ cultivar that in the second year, fruit and oil yield was respectively 58 and 57 percent more than the first control in the same cultivar. In the first year, the highest oil percentage in the dry matter, belongs to the second control in the ‘Roughany’ cultivar. While, two years after treatment, the trees that treated with 24 and 36 kg of compost in the ‘Roughany’ cultivar had about 10 percentage of oil in dry matter more the trees that treated with manure in the same cultivar. Fruit weight, pit weight and fruit pulp percentage in ‘Zard’ cultivar was higher than ‘Roughany’ cultivar over two years. In the second year after treatment, the trees that treated with 36 kg of compost in ‘Zard’ cultivar had the highest fruit weigh and also pulp weight and pulp to pit ratio was more than the manur treatment in the same cultivar.
The highest nitrogen, in the first year after the treatment blonged to ‘Roughany’ cultivar, with 24 kg compost, that was more 26 percent than the first control in the same cultivar. In the second year after treatment blonged to ‘Roughany’ cultivar, with 24 kg compost, that was more 26 percent than the first control in the same cultivar. Two years after treatment, the trees were treated with 36 kg of compost had 10 percent more phosphorus than the first control. Also in this year, the ‘Zard’ cultivar had nine percent more potassium than the ‘Roughany’ cultivar. In the first year, ‘Zard’ cultivar had more calcium and magnesium, and less phosphorus and sodium than the ‘Roughany’ cultivar, respectively. In the second year after treatment, calcium and magnesium in the trees that treated with 24 and 36 kg compost was at the highest level statistically. The ratio of sodium to potassium in the first and second year, in the ‘Zard’ cultivar was less than’Roughany’ cultivar.
Conclusion:It seem olive trees that fertilized with olive mill pomace compost especially with 36 kg could improve nutrition status of olive tree such as leaf N, P, Ca and Mg in leaves and consequently improves fruit and oil yield and fruit quality especially in ‘Zard’ cultivar.