Influence of olive oil solid waste applications on soil pH, electrical conductivity, soil nitrogen transformations, carbon content and aggregate stability

Some of the agricultural wastes have important economic potentials to be used as a plant nutrition and/or soil conditioner. Olive oil solid waste (OSW) is one of them. The aim of this study was to determine effects of OSW on soil pH, electrical conductivity (EC), improving soil nitrogen (N) status, soil aggregate stability and soil carbon contents. Different rates of OSW (control, 2%, 4% and 8%, w/w) were applied to coarse soils and incubated for 2 months. OSW applications decreased soil pH values. The mean EC value of soil measured 2 months after the incubation was greater than that of the first month. Application of OSW at the rate of 8% has significantly increased soil total organic nitrogen contents. OSW applications at the rate of 8% (w/w) significantly increased both mean SOC content (3.5%) and aggregate stability (88%) after 2 months of incubation (p < 0.01). Therefore, OSW has great potential to improve soil structure of coarse textured soil in short term.