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Evaluation of long-term water management strategies for saving water and reducing nitrogen and phosphorus losses from agricultural fields: controlled drainage and surface flow constructed wetland case studies in Venice Lagoon drainage basin
Full text linkIn in contesto di carenza idrica e di inquinamento delle acque superficiali causato dalle attività agricole, devono essere identificate nuove pratiche di gestione delle risorse idriche che rispondano a queste problematiche e possano essere utilizzate in diversi ambienti.
Il bacino idrografico della Laguna di Venezia (nell'Italia nord-orientale) è un'area sensibile all'inquinamento delle acque superficiali. La prevalenza di terreni pianeggianti e la presenza di una falda freatica superficiale, tuttavia, suggeriscono condizioni idonee per la realizzazione di due pratiche di gestione idrica per la riduzione dei carichi di N e P provenienti dalle aree agricole: il drenaggio controllato (controlled drainage: CD) e le wetland artificiali a flusso superficiale (surface flow constructed wetlands: SFCWs). Il monitoraggio di lungo periodo delle performance di queste pratiche è necessario per fornire risultati di validità generale, che non siano condizionati dalla variabilità meteorologica annuale.
Questo lavoro valuta le performance di un sistema di CD e di SFCW in un esperimento di lungo periodo. Il CD è stato monitorato durante i periodi 1995-2002 e 2006-2013, in termini di bilancio idrico e di resa delle colture, e dal 2007 al 2013 anche per le perdite di N e P. La SFCW è stata monitorata dal 2007 al 2013 per la riduzione dei carichi di N e P.
Il CD ha permesso di ridurre i deflussi idrici del 69% e ha determinato un aumento complessivo della resa di granella di mais del 26,3%, e della resa di mais da insilato del 4,0%. Le perdite di NO3-N e PO4-P nelle acque superficiali sono state ridotte rispettivamente del 92% e del 65%.
La SFCW ha mostrato tassi di rimozione annui apparenti dell'83% e del 79% rispettivamente per NO3-N e N totale, e del 48% e del 67% rispettivamente per PO4-P e P totale.
Sia il CD che la SFCW si sono rivelati efficaci nel ridurre i carichi inquinanti di N e P, ed il CD ha anche contribuito ad aumentare la resa delle colture attraverso il risparmio idrico. Per questi motivi, l'applicazione di queste due pratiche di gestione idrica è da prendersi in considerazione in questo ambiente
Efficiency of controlled drainage and land drainage system in improving water saving and reducing non-poin source pollution in a five-year trial
No full text7-year N and P balance of a Surface Flow Constructed Wetland in advanced stage: a case study in North-Eastern Italy
No full textCrop yield responses to water table management with different drainage systems in a long term trial
No full textWater table management to save water and reduce nutrient losses from agricultural fields: 6 years of experience in North-Eastern Italy
No full textTo evaluate the performances of a controlled drainage system in optimizing water use and reducing nutrient losses from agricultural fields, an experimental facility was set up in north-eastern Italy in 1996. Water table management was tested in combination with surface (open ditches) and subsurface (pipe) drainage systems. Data were collected from 2007 to 2013 on: water table depth, drained volumes, nitrogen and phosphorus concentrations in groundwater and in drainage water.
Nitrogen in groundwater showed higher concentrations when controlled drainage was combined with open ditches system, with a median of 13.43 mg L-1 for NO3-N and 18.68 mg L-1 for total N. Drainage water showed an opposite trend: subsurface pipes with free drainage provided highest concentrations due to extensive leaching (a median of 20.7 mg L-1 for NO3-N and 24.0 mg L-1 for total N). Phosphorus concentrations showed notable differences in drainage water, with higher values in the controlled drainage – open ditches system due to surface runoff (a median of 0.190 mg L-1 for PO4-P and 0.536 mg L-1 for total P).
In general, the most hazardous period for surface water pollution was autumn-winter, due to rainy weather and fertilizer application on bare soil.
Overall, water table management reduced total water discharge by 81% compared to free drainage. On average, with controlled drainage annual nitrogen losses were lowered by 92% (from 29 to 2 kg NO3-N ha-1) and annual phosphorus by 65% (from 0.14 to 0.05 kg PO-4P ha-1). Free drainage with subsurface pipe was the worst combination from the environmental point of view: annual nitrogen and phosphorus losses were 46 kg NO3-N ha-1 and 0.10 kg PO4-P ha-1 respectively.
Water table management clearly proved to be a reliable tool to improve both water usage and quality
Influence of Irrigation Frequency on Radicchio (Cichorium Intybus L.) Yield
Full text linkRed chicory (radicchio) plants produce leafy heads that are of great commercial interest and they require a proper irrigation technique to achieve satisfactory productivity. The use of mini-sprinklers with high-frequency irrigation schedules may increase radicchio productivity, provide better growing conditions due to timely intervention, and save water, but so far little research has been carried out on this topic. This experiment aims at evaluating the effect of two mini-sprinkler irrigation schedules (high- and low-frequency) on radicchio yield and growing conditions over a 5-year cultivation period. Marketable radicchio head production was on average 12% greater with the high-frequency schedule (26.5 t ha-1) than with the low-frequency schedule (23.6 t ha-1), mainly due to greater head weight. The number of underweight, pre-flowering, rotten, and missing plants was significantly different between the two schedules when these variables were considered separately, but the overall number of marketable plants was greater in the high-frequency schedule during certain years. In general, the high-frequency schedule permitted to increase both radicchio yield and to reduce irrigation water use on average by 14% (-24 mm in volume), improving the irrigation water productivity by 19% (from 0.18 t mm-1 of the low-frequency schedule to 0.22 t mm-1 of the high-frequency schedule). Reducing the irrigation interval permits a timely adaptation to the weather course and improves radicchio growing conditions, presenting itself as a valid strategy that could be adopted by the farmers, upon appropriate consideration of energy and management costs
Predicting Soil Carbon Dynamics in Organic Farming Topsoil: A Model Calibrated to Account for Crop and Weed Residues
No full textLONG-TERM YIELD AND ENVIRONMENTAL EFFICIENY OF ORGANIC AND CONVENTIONAL SYSTEMS IN NORTH-EASTERN ITALY
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