**2. Materials and Methods**

## *2.1. Sample Collection Areas*

The soil samples examined were collected from three areas in Greece, and more specifically, from the Prefectures of Lakonia, Argolida and from the island of Kos. Specifically, 50 soil samples were collected from Laconia from irrigated olive groves. The sampling procedure was carried out in September after the irrigation period. In Argolida, 12 samples were collected from various irrigated crops at the end of the irrigation period, while in Kos, 27 samples were collected from a horticultural greenhouse. The depth of soil samples collection was up to 30 cm.

#### *2.2. Methods of Determining the Soil Properties*

After sampling, the samples were transferred to the laboratory for air-drying and sieving through a 2 mm sieve and the soil texture, pH and calcium carbonate were determined. Soil texture was determined by means of the Bouyoucos hydrometer method [23], pH values were measured using standard glass/calomel electrodes in 1:2.5 w/v soil–water suspension [24]; CaCO<sup>3</sup> equivalent percentage was estimated by measuring the eluted CO<sup>2</sup> following the addition of HCl (calcimeter Bernard method).

#### *2.3. Methods of Various Soil Extraction and Measurements*
