Soil inventory and monitoring. Current issues and gaps

Soil is a vital, non-renewable resource providing essential support to human life, society and to ecosystem services. The quality of soil must be enhanced, maintained or restored in order to provide its essential functions such as nutrient release, water storage, filtering and transfer, habitat provision, carbon storage and contributing to food security. Political awareness that soil is under increasing pressures and threats has been rising for several years (EC, 2006). Although rates of soil degradation are often slow and only detectable over a multi-annual timescale they are nevertheless frequently irreversible. This is why we must monitor soil quality in order to detect changes early on. Such early detection should enable the design and implementation of policy measures to protect and maintain the sustainable use of soil. Soil monitoring is the systematic determination of soil variables so as to record their temporal and spatial changes (FAO/ECE, 1994). Soil monitoring enables the early detection of changes in soil quality, both negative and positive. As such, it is an essential tool for assessing the effectiveness of soil protection policies. The detection of changes also enables fuller understanding of the actions of soil processes involved in soil degradation or improvement. This gives the opportunity for informed policy decisions to be made in order to protect and to conserve soils for their sustainable use and for general environmental control. A recent review undertaken within the ENVASSO project, funded under the European Commission’s 6th Framework Programme of Research, described the majority of existing soil monitoring networks in Europe, and identified differences in their spatial coverage and scope (Morvan et al., 2008; Kibblewhite et al., 2008). It was found that in many countries of Europe, national monitoring sites have, as yet, been sampled only once, and therefore, the monitoring network can only be considered to be an inventory. This large consortium project identified many issues which were common across Europe and which required more research. The idea of putting together contributions that might address some of these issues of soil inventory and monitoring into a thematic issue of the European Journal of Soil Science arose during the final consortium meeting of the ENVASSO project in November 2007 in Bordeaux, France. There are many scientific issues related to inventory development and soil monitoring that need to be addressed to ensure that networks will be able to detect change in soil over relevant spatial and temporal scales. These include design and implementation of sampling in space and time, choice of relevant indicators, development and testing of new analytical techniques, harmonization of