An integrated non point source model-GIS system for selecting criteria of best management practices in the Po valley, North Italy

To 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.