The effect of the use of vermicompost, leonardite and pomace on some soil properties in olive cultivation

This research was carried out on a 12-year-old Gemlik variety olive grove, located in the historical Deyrulzafaran Monastery in the Artuklu district of Mardin province, Turkey, in the years 2020-2021. The effect of the use of vermicompost, leonardite and pomace, which are known as organic soil improvers, on some properties of soil under olive trees was investigated. The treatments were applied in February 2020 and repeated in February 2021 during the pre-flowering period of olives. At the end of the applications, the soil was analyzed in July 2022. For this purpose, samples were taken from two different depths, 0-30 and 30-60 cm, to represent the orchard soil under an olive grove. According to the research results, the pH of the soil samples taken from the olive orchard, measured in the saturation sludge, varied between 7.18 and 7.69, and the soil was determined to be of neutral and slightly alkaline reaction. The organic matter content of the garden soil, which was determined to have loamy texture (L) with a salt-free structure, proved to rank as follows: pomace > leonardite > vermicompost-treated soil, with the latter having the highest organic matter content compared to the control group. The %N content in the soils increased in the order: vermicompost > pomace > leonardite, the latter being the highest compared to the control group. In soil samples, the following elements were determined in the following quantities: phosphorus 3.01-6.12 kg da^-1, potassium 40.00-44.80 kg da^-1, calcium 2500-7370 mg kg^-1, magnesium 350-422 mg kg^-1, sodium 4.42-6.02 mg kg^-1, iron 8.19-15.20 mg kg^-1, copper 8.44-13.10 mg kg^-1 and manganese 26.30-38.70 mg kg^-1. It was determined that the phosphorus content of the soils was very low in soil samples taken from 30-60 cm depth, and moderate in soil samples taken from 0-30 cm depth. The potassium content of the soils was determined to be low. All the soil samples were determined to contain excess amounts of calcium. Finally, all the garden soil samples were found to contain adequate amounts of Mg, Na, Fe, Cu and Mn.