Soils sampling planning in traceability studies by means of experimental design approaches

The present research is part of a project dealing with the development of analytical methodologies mainly based on primary indicators, such as isotopic ratio of radiogenic elements, for theauthenticity and geographical traceability of oenological food, typical of the Modena district. In particular, considering the objective of establishing a food-territory link by means of these analytical indicators, it is straightforward how the representativeness of sampling for both food and soils, covers a primary role in the robustness of the traceability models. With the aim of building traceability models for oenological matrices, the issue of selecting a set of representative, informative and different soil samples is tackled. In this case, the goal is not obtaining a set of soil samples uniformly spanning the territory to be investigated, since the planning of a punctual sampling extended in the whole district of Modena is not feasible considering the total number of samples affordable by the study, but rather to choose a representative set of vineyards were to locate the soil samples. Thus, all the vineyard-registered producers of the district of Modena were considered and different variables (geological features of the soils, winegrowing coverage, grapes varieties, yearly productions of the farms, etc.) were handled with Experimental Design (DoE) techniques in order to simultaneously taking into account the different kinds of information for achieving a sustainable and rational site sampling. In particular, D-Optimal Onion design was chosen since it is widely used for mapping and planning purposes, hence it consents to achieve the maximum coverage and uniformity of the selected samples in the whole domain. An efficient mapping of geographical region has been obtained ensuring coverage of farms characterized by main grape production and insisting on soils with different geological features.