Land use in relation to soil chemical and biochemical properties in a semiarid Mediterranean environment

Low organic matter levels and fragile structure of coarse textured soils from and and semiarid environments can lead to progressive degradation of their quality and productivity. Our objective was to evaluate the effects of land use on soil organic matter quality and quantity and biochemical properties related to soil microbial activity that are involved in the cycling of nutrients and carbon. Four sandy soils under different agricultural practices and four adjacent soils under grass cover in a Mediterranean environment comprising the humid-temperature climate of centralwest Italy were characterised chemically and biochemically. A sensitivity index was calculated for each of the measured properties by dividing the values for uncultivated soils with their cultivated counterparts. A metabolic potential index was calculated as the ratio between dehydrogenase activity (DHase), and water-soluble carbon (WSC). There was a general decline of total organic carbon (TOC), extractable humic substances (HS), WSC, water-soluble carbohydrates (WSCH), DHase, urease, protease, phosphatase and beta-glucosidase activities following the different agricultural practices with respect to soil under grass cover. DHase, urease and phosphatase activities were more sensitive and responded more frequently to land use than TOC and WSC and WSCH. DHase/WSC ratio confirmed the reduction of cultivated soils metabolism as consequence of management practices. (C) 2002 Elsevier Science B.V. All rights reserved.