2.3. Soil materialTen sites were randomly chosen and sub-samples were col-lected up to a depth of 15 cm (A horizon = 20 cm), after removingthe top layer. After combining the sub-samples, they were sieved(2 mm × 2 mm) to remove root residues and coarse material andstored in polyethylene bags at 5◦C until used.2.4. Chemical and microbiological soil analysisWater content (WC) was determined by drying an aliquot (×2)until constant weight at 105◦C [7]. Bulk density and field capac-ity humidity (FCH) were determined by the graduated cylindermethod [8]. The pH was measured with a glass electrode ona suspension of soil in deionised water (1:1) [8]. Organic car-bon (OC) was determined by wet oxidation with K2Cr2O7/H2SO4[9]. Extractable phosphorus (P) was photometrically determinedby the Olsen extraction method [10]. Extractable nitrogen asNO3−+ NO2−+ NH4+was determined by the diffusion method [11].Colony forming units (CFU g−1) were determined by the serial dilu-tion method by using trypteine soy agar (TSA) as culture media.