Description of chemical and biological soil characteristics of two fields subjected to different agricultural management under Mediterranean conditions

Several factors such as soil pollution and intensive agricultural management continuously damage the sustainability of agricultural production, with potentially adverse effects on soil quality. It is important to create applicable and valid soil quality indicators in order to both identify areas with potential productivity problems and monitor soil quality changes due to a range of perturbations. In this work we compared several chemical and biological variables between a Mediterranean soil characterized by intensive horticulture that has been irrigated for 20 years with moderately saline waters (IM) and an adjacent soil, subjected to a sustainable agricultural production management and irrigated with plain water (SM). Soil sampling was repeated three times during a year in both sites. IM soil had lower pH, organic carbon and total nitrogen compared to SM soil at all sampling times, while its electrical conductivity was significantly higher at two sampling times only. Potentially mineralizable nitrogen pointed out significant differences only at the first sampling time, with lower levels in the SM soil. β-sitosterol, cholesterol and ergosterol varied significantly with sampling time and were influenced also by management. Statistical approach by Principal Component Analysis highlighted a contrast between two groups of soil variables: potentially mineralizable nitrogen and sterols mainly weighted on the first axis, while chemical properties, weighted on the second one. Moreover, the second axis separated the soil subjected to a sustainable agricultural production system from that subjected to intensive practice management, while the first axis separated the third sampling data from the first two.