Options for harmonising soil data obtained from different sources

This review was prepared in conjunction with the EU HoliSoils project (Grant agreement No. 101000289) and ISRIC’s ongoing WoSIS (World Soil Information Service) programme. It investigates posibilities for harmonisation of discongruent soil data obtained from a diverse range of data providers. Various approaches, expressed in terms of tier levels, towards full harmonisation are discussed. The actual choice for, or feasibility of, a given approach is largely detemined by the fact whether new soil monitoring programmes can be set up or whether only soil legacy data are available. These considerations determine the level of harmonisation of soil data achievable in the framework of the World Soil Information Service. WoSIS-derived data will underpin the digital soil mapping work of the HoliSoils project, with a focus on forest soils in Europe.