Steps towards the construction of the soil database of the Mediterranean region

The importance of soil data has grown with the increased need for sustainable land management and for addressing soil degradation threats, leading to the development of global soil databases and mapping tools. There is increasing demand for standardized, accessible, and detailed soil information to feed a range of national and international applications related to digital soil mapping and soil monitoring. Legacy soil data constitute a relatively underutilized source of soil information. They are available in formats corresponding to the time and place of collection, and they often differ in standards for soil profile descriptions, laboratory methods, classification systems, map scales, georeferencing systems, data density, and formats. Therefore, the potential of these data can be exploited only if proper harmonization processes are developed and implemented, to make them interoperable with current soil description and classification systems, and data management tools. In the Mediterranean region (MR) and the Near East and North Africa (NENA) countries, steps toward this goal are being taken through the PRIMA-funded SOILS4MED project involving partners located in Italy, Lebanon, Spain, Tunisia, Greece, Egypt, Jordan, Turkey, and Morocco. This initiative focuses on monitoring soil health and developing information systems to promote sustainable soil management. The project aims to collect, digitize, harmonize, and make available in the frame of country-owned Soil Information System (SIS), all the available legacy data at partner countries. Over 11,000 soil profiles and 120 maps have been collected, with contributions from research institutes like IAO, CREA, and IRD/ORSTOM. The maps were scanned, digitized, and their classification systems were translated according to the WRB 2022 standards. The process for legacy soil profile data involved: (i) a comprehensive review of the collected data, (ii) detailed analysis of their different data models (different survey methods and coding/archiving systems and different classification systems), (iii) data selection, (iv) digitalization and harmonization of all the data according to the adopted standard data model. The latter was based on the WRB 4th Edition soil classification and survey guidelines. When the original survey methods differed from WRB 2022, conversion tables created by the team were used to translate classifications into the WRB 2022 system. In fact, legacy soil classification systems were widely varied, ranging from CPCS, Référentiel pédologique, USDA Soil Taxonomy of many different editions, FAO or old WRB systems. This process of collecting, evaluating, integrating, and harmonizing legacy data using a single data model and classification system (WRB 2022) enabled the design and implementation of the first WRB 2022-compliant SIS-database, which will be shared with the international community as a result of the SOILS4MED Project.