Assessment of Potential Territorial Suitability for the Sustainable Production of the “Acquaviva Red Onion” (Allium Cepa L.): A Study Using Overlapping Approach

The onion (Allium cepa L.) is one of the most important horticultural crops worldwide; it is widely appreciated by consumers for its nutraceutical effects. In the extreme South of the Murgia area (Apulia, Italy), the Acquaviva red onion has been cultivated for a very long time, as an excellence of this territory. The production of this product typically extends across a rather limited and substantially confined area within the municipality of Acquaviva delle Fonti. Therefore, this circumscribed oasis of production demands territorial planning policies aimed at valorizing its sustainable production by safeguarding the soils most suited to this typicality of production, whose erosion would result in the disappearance of a product with high territorial value. In order to assess the potential territorial suitability for the Acquaviva red onion, data on climate (average temperature and precipitation), soil (texture, pH, electrical conductivity and organic matter content), topography (altitude and slope) and land use were found for each district, through preliminary surveys, and using the Informative Territorial System (SIT Puglia) database. Territorial suitability ranges were established, based on the onion cultivation needs and the indications of the Designation of Municipal Origin (DE.C.O) production specification and the Slow Food production specification for Acquaviva red onion. Using the GIS software Arcmap Arcgis 10.5, all information layers were overlapped, obtaining the maps of suitability for each feature. Finally, from the overlap of these, it was possible to obtain an overall map of the areas with a greater territorial suitability. The results obtained suggest that accurate territorial planning can be integrated with the contents of a regional development program that is attentive to the valorisation of this typical local product. Beyond the purposes described above, this method could be extended to conterminous territorial areas to verify the possible expansion of the optimal production area.