As the increase of nitrate concentration in groundwater has often been ascribed to an inappropriate use of liquid manure, the main purpose of this study was to better understand the factors controlling nitrate dynamics in the unsaturated zone of soils subjected to characteristic agronomic practices, and to contribute to improving Action Programmes, with reference to EU Directive 91/676, for Nitrate Vulnerable Zones (NVZ). Water infiltration and nitrate leaching have been studied in experimental fields located inside Nitrate Vulnerable Zones of the Emilia-Romagna region (Northern Italy), characterized by different pedological and hydrogeological properties and equipped with tensiometers, ceramic-cup samplers and piezometers. This article describes the results obtained from one of these sites, monitored over a six year period, which was cereal cropped and treated with pig slurry. Field data for the first three years of the experiment have been used to calibrate MACRO and SOILN field-scale models, simulating water flow and nitrogen transport. The results demonstrate how nitrogen inputs from slurry, substantially higher than crop uptake, causes nitrates accumulation in the surface layer of the soil especially in warm periods (concentrations of up to 300 mg NO3-N l-1 were found in soil water). Even if the soil texture was fine, the shrink-swell properties of clay minerals determined fast drainage conditions (related to macroporosity), so that during the early rainy periods nitrates leached through the first meters of the unsaturated zone, at least down to 4 m. This shows that nitrate accumulation should be limited before these periods, i.e. by reducing manure application rates, especially if the soil is to be left uncultivated . The results from the models were consistent with the experimental data and hence testified that MACRO and SOILN are suitable tools for predicting such phenomena, even though their calibration require some further refinements.
Mantovi, P., Fumagalli, M., Beretta, G., Guermandi, M. (2006). Nitrate leaching through the unsaturated zone following pig slurry applicatons. JOURNAL OF HYDROLOGY, 316(1-4), 195-212 [10.1016/j.jhydrol.2005.04.026].
Nitrate leaching through the unsaturated zone following pig slurry applicatons
FUMAGALLI, MARIA LETIZIA;
2006
Abstract
As the increase of nitrate concentration in groundwater has often been ascribed to an inappropriate use of liquid manure, the main purpose of this study was to better understand the factors controlling nitrate dynamics in the unsaturated zone of soils subjected to characteristic agronomic practices, and to contribute to improving Action Programmes, with reference to EU Directive 91/676, for Nitrate Vulnerable Zones (NVZ). Water infiltration and nitrate leaching have been studied in experimental fields located inside Nitrate Vulnerable Zones of the Emilia-Romagna region (Northern Italy), characterized by different pedological and hydrogeological properties and equipped with tensiometers, ceramic-cup samplers and piezometers. This article describes the results obtained from one of these sites, monitored over a six year period, which was cereal cropped and treated with pig slurry. Field data for the first three years of the experiment have been used to calibrate MACRO and SOILN field-scale models, simulating water flow and nitrogen transport. The results demonstrate how nitrogen inputs from slurry, substantially higher than crop uptake, causes nitrates accumulation in the surface layer of the soil especially in warm periods (concentrations of up to 300 mg NO3-N l-1 were found in soil water). Even if the soil texture was fine, the shrink-swell properties of clay minerals determined fast drainage conditions (related to macroporosity), so that during the early rainy periods nitrates leached through the first meters of the unsaturated zone, at least down to 4 m. This shows that nitrate accumulation should be limited before these periods, i.e. by reducing manure application rates, especially if the soil is to be left uncultivated . The results from the models were consistent with the experimental data and hence testified that MACRO and SOILN are suitable tools for predicting such phenomena, even though their calibration require some further refinements.
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