1,721,053 research outputs found
Long-term pan evaporation observations: a precious resource to understand the water cycle trend
No full textAcceleration of the global water cycle over recent decades remains uncertain because of the high inter-annual variability of its components. Observations of pan evaporation (Epan), a proxy of potential evapotranspiration (ETp), may help to identify trends in the water cycle over long periods. The complementary relationship (CR) states that ETp and actual evapotranspiration (ETa) depend on each other in a complementary manner, through land-atmosphere feedbacks in water-limited environments. Using a long-term series of Epan observations in Australia, we estimated monthly ETa by the CR and compared our estimates with ETa measured at eddy covariance Fluxnet stations. The results confirm that our approach, entirely data-driven, can reliably estimate ETa only in water-limited conditions. Furthermore, our analysis indicated that ETa did not show any significant trend in the last 30 years, while short-term analysis may indicate a rapid climate change that is not perceived in a long-term perspective.Editor Z.W. Kundzewicz; Associate editor D. GertenCitation Lugato, E., Alberti, G., Gioli. B., Kaplan, J.O., Peressotti, A., and Miglietta, F., 2013. Long-term pan evaporation observations as a resource to understand the water cycle trend: case studies from Australia. Hydrological Sciences Journal, 58 (6), 1287-1296. © 2013 IAHS Press
Olsen phosphorus, exchangeable cations and salinity in two long-term experiments of north-eastern Italy and assessment of soil quality evolution
No full textDue to its food production and environmental buffering functions, soil is considered a strategic target by the European Union and its
quality evaluation could be used as an effective index of sustainability. The evolution of some soil chemical parameters has been studied in
two long-term trials established in the early 1960s in north-eastern Italy: one (SF) comparing nutrient management treatments (i.e. organic,
mineral and mixed fertilizers) in lysimeters containing widely contrasting soil types (i.e. sand, clay and peat) and the other (CR) involving a
field study with crop rotation, nutrient (organic vs. mineral fertilizers), and management intensity variables. Soil was analysed for Olsen
phosphorus (Pav), exchangeable cations (Kex, Naex, Mgex and Caex) and salinity, evaluated by measuring the electrical conductivity (EC). A
bi-factorial quality index based on fuzzy logic was then tested and applied to assess the overall soil quality and its evolution in the cropping
systems. A minimum dataset of chemical (pH, organic carbon, cation exchange capacity, Pav and Kex) and physical parameters (available
water content and water-filled porosity) was used to elaborate the index. In general, the use of organic fertilizer resulted in higher Pav, Kex
and Mgex concentrations than the mineral treatments at the same levels, whereas no differences for Naex and Caex were observed. Salinity
level was not influenced by the organic treatments probably because the consistent water drainage in the area prevented salt accumulation.
The soil quality index represented the soil productivity function, explaining up to 74% of yield variability. Index comparison highlighted
the positive role of organic and mixed fertilizations in increasing and maintaining the soil quality. The bi-factorial index of soil quality
based on a minimum dataset is a good tool for the policy maker to evaluate the effects of management practices. However, standardization
and accuracy of the soil analyses are important to reduce sources of variability that could have a strong influence on the soil quality
evaluation
An integrated non point source model-GIS system for selecting criteria of best management practices in the Po valley, North Italy
No full textTo guarantee high production standards which respect the environment, decision-makers in the European Community must promote best management practices (BMPs). Given the strong interactions between pedo-climatic conditions and management, decision support systems are useful tools for selecting the more effective BMPs. An integrated non-point source (NPS) model-GIS system was designed to evaluate the production and environmental effects of alternative criteria of BMPs in the Mincio River Basin (NE-Italy). It is based on an integration of the CropSyst model (version 3.02.21) with a high informational level GIS developed in the Arc/Info environment. Three alternative criteria were evaluated: (1) obtaining maximum irrigation efficiency; (2) obtaining maximum nitrogen (N) fertilisation efficiency; (3) obtaining combined maximum irrigation and N fertilisation efficiency. The hypothetical criteria were compared applying multicriteria analysis of concordance/discordance to a set of agro-environmental indicators. The latter were obtained from field-scale CropSyst applications in the study area in the period 1994-2000. Application of the system required a preliminary 2-year validation phase of CropSyst on 12 experimental sites in the Basin that are heterogeneous in terms of climate, soil and management. The multi-criteria analysis considered the actors currently involved in the management of the Basin area: the farmer, environmentalist and politician. This application demonstrated that water flow control, through irrigation rationalisation, is the critical point for reducing pollution in the area. This allowed crop yield to be improved with a contemporary reduction in irrigation depths (50%) and nitrogen leaching (more than 50%). Irrigation rationalisation represents the best compromise between the farmers' production and livestock waste disposal requirements and the environmentalists' desire for water saving and protection. The GIS-CropSyst integration considers the different pedo-climatic and crop combinations and represents a valid support for territorial management and planning
Agricultural Land Use and N losses to water: the case study of a fluvial park in Northern Italy
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L'analisi multicriterio dei sistemi colturali/Multicriteria analysis of the cropping systems
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Estimation of mean residence time (MRT) of soil organic carbon (SOC) in soils with contrasting texture
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