SUBMERGED PEDOLOGY: THE SOILS OF MINOR ISLANDS IN THE VENICE LAGOON

Minor islands of the Venice lagoon are part of a delicate ecosystem, with equilibrium that depends on multiple factors deriving from both the aqueous and the terrestrial compartment, and represent useful indicators of the lagoon ecosystem status. Over centuries, some islands emerged, some others disappeared, others are being submerged in consequence of sea level rise, or are dismantled by marine erosion. Ecological survey and soil sampling evidenced rather homogeneous environment and soil characters, likely due to the same genesis from HTM during centuries, and to environmental conditions such as moisture and brackish groundwater. Four of the examined soils are Inceptisols, while the others present limited horizon differentiation, and are Entisols. All the profiles reflect udic or aquic conditions, and some of them are submerged for most time. Most soils are moderately alkaline (7.9 250 g/kg); organic carbon content at surface is within the normal range (8 <OC g/kg< 12), while at depth it is low (< 8 g/kg). The soils of shallow sandbanks differ from those of the islands having neutral pH (6.6 17 g/kg) and carbonates. Moreover, the textural class is generally silty-loam with increasing clay content with depth. Currently, the soils examined present hydromorphic pedofeatures, which are the result of the most important pedogenic process in the lagoon. Alternating reduction/oxidation processes would increase as a consequence of sea level rise, determining reducing conditions at bottom, and conversely enhancing salt concentration uppermost, with negative consequences for both pedogenic evolution and vegetation survival

Assessment of total soil and plant trace elements in rice-based production systems in NE Italy

Recently, the widespread interest on soil enzymes is due to the need to develop sensitive indicators of soil quality that reflect the effects of land management on soil and assist land managers in promoting long-term sustainability of terrestrial ecosystems. The activities of six important enzymes involved in C, N, P, and S cycling were investigated in a paddy soil from the Veneto region, Italy, in four different rotation systems (rice-rice-rice, soya-rice-rice, fallow-rice and pea-soya-rice) with three replications in April (after field preparation, field moist condition), June (after seedling, waterlogged soil condition), August (after tillering stage of rice, waterlogged soil condition) and October (after rice harvesting, drained soil condition) over the 2012 growing season. Our results demonstrated that soil enzyme activities varied with rotation systems and growth stages in paddy field. Compared with field moist soil, drained soil condition resulted in a significant increase (P < 0.05) of β-glucosidase, arylsulfatase, alkaline and acid phosphatases, leucine aminopeptidase (except of F-R), and chitinase activities in all rotations, while compared with drained soil, waterlogging (in month of June, the early period of waterlogging) significantly decreased (P<0.05) β-glucosidase, alkaline and acid phosphatases, leucine aminopeptidase (except of P-S-R), arylsulfatase, chitinases. Soil organic-C was positively correlated with acid and alkaline phosphatases, and arylsulfatase while ß-glucosidase, chitinases and leucine aminopeptidase were not significantly correlated to soil organic-C. Enzyme activities were always correlated among them