Camillo Zanchi

Raindrop Size Distribution and Soil Erosion

AbstractSoil erosion is caused, at least in part, by the effect of kinetic energy on the soil during rainfall. Therefore, a better knowledge of rain parameters is useful. To assess the influence of rain on the amount of soil loss, an experimental site was set up in the Chianti hills (central Italy). Tipping-bucket rain gauges and the Joss-Waldvogel disdrometers were used. A colocated system of gauges provided soil loss and runoff measurements for rainfall events that occurred between September 2006 and June 2007. The reliability of a widely used rainfall erosion index was also assessed and the effect of kinetic energy, computed by the measured drop size distribution, evaluated. The results highlighted the potential of the physical approach in computing the kinetic energy developed by the rain drops to the soil, especially for higher rainrates and when the hydrological balance is positive or slightly negative. The kinetic energy estimate from the rain rate well reproduces the measured values only below 10 ...

Leaching of Glyphosate and Aminomethylphosphonic Acid through Silty Clay Soil Columns under Outdoor Conditions.

Glyphosate [-(phosphono-methyl)-glycine] is the main herbicide used in the Chianti vineyards. Considering the pollution risk of the water table and that the vineyard tile drain may deliver this pollutant into nearby streams, the objective of the present study was to estimate the leaching losses of glyphosate under natural rainfall conditions in a silty clay soil in the Chianti area. The leaching of glyphosate and its metabolite (aminomethylphosphonic acid [AMPA]) through soils was studied in 1-m-deep soil columns under outdoor conditions over a 3-yr period. Glyphosate was detected in the leachates for up to 26 d after treatments at concentrations ranging between 0.5 and 13.5 μg L. The final peak (0.28 μg L) appeared in the leachates approximately 319 d after the first annual treatment. Aminomethylphosphonic acid first appeared (21.3 μg L) in the soil leachate 6.8 d after the first annual treatment. Aminomethylphosphonic acid detection frequency and measured concentration in the leachates were more than that observed for the glyphosate. Aminomethylphosphonic acid was detected in 20% of the soil leachates at concentrations ranging from 1 to 24.9 μg L. No extractable glyphosate was detected in the soil profile. However, the AMPA content in the lowest layer ranged from 13.4 to 21.1 mg kg, and on the surface layer, it ranged from 86.7 to 94 mg kg. Overall, these results indicate that both glyphosate and AMPA leaching through a 1-m soil column may be potential groundwater contaminants.

Soil Salinisation in the Grosseto Plain (Maremma, Italy): An Environmental and Socio-Economic Analysis of the Impact on the Agro-Ecosystem

Soil salinisation jeopardises economy and landscape formed in Grosseto Plain during the last two centuries. Observed evidences show that soil salinisation is not due to climate change and rain reduction, but predominantly to the agricultural techniques of the local farms, which require large water supplies for irrigation. Water is drawn heavily from brackish water bodies too. In turn, in this coastal zone the excessive exploitation of groundwater increases the entry of salt water from the sea into the groundwater table. This research indicates alternative agricultural techniques fit to avoid soil salinisation and aimed at maintaining agricultural profitability as well as the landscape in the Grosseto Plain.

Prediction of Soil and Nutrient Losses on Chianti Vineyard with SWAT Model

In Mediterranean area, hillside vineyards are frequently subjected to high soil losses due mainly to improper management techniques which influence the dynamics of nutrients. The aim of this study is to evaluate the “Soil and Water Assessment Tool” (SWAT) performance in predicting nitrogen and phosphorus content in runoff and soil particles transported from experimental fields. Runoff volume and composition was measured during several rainfall events (87), measured from January 2005 to December 2008, in instrumented up-down slope vineyard at the Montepaldi Farm - University of Florence, in Tuscany (Italy). Both harrowed and grassed inter-row management techniques were evaluated. SWAT was tested using a 10 min runoff model to simulate hydrology, then model results were compared with field observations. Notwithstanding the SWAT model overestimates the soil loss and the runoff, the results of this study show good agreement between simulated and measured data both for runoff and soil loss with Nash-Sutcliffe efficiency (NSE) values, both for harrowed and grassed plots higher 0.89. Moreover the SWAT model performed satisfactorily in simulating daily nitrogen and phosphorus losses, both on grassed and harrowed plots, with a NSE higher than 0.92 both for the calibration period and validation period.