Soil Functions—An Introduction

It is now widely recognised that soils not only provide food but in addition, they deliver a wide range of ecosystem services to society. The EU Thematic Strategy on Soils (2006) identified seven ‘environmental, economic, social and cultural functions’. In research studies from Ireland, these ecosystem services have been rearranged into the following five main soil functions for agricultural land (1) primary production, (2) water purification and regulation, (3) carbon storage and sequestration, (4) habitat for intrinsic and functional biodiversity and (5) the cycling and provision of nutrients. In addition, soils also provide two ancillary functions, namely: (6) a platform for infrastructure (e.g. roads, buildings) and (7) an outdoor archive of archaeological heritage. In principle, all soils perform each of these functions simultaneously. However, the extent to which each function is delivered depends in the first instance, on land use. For example, the functionality of arable soils is characterised by primary production and nutrient cycling. Second, the functionality of soils depends on soil properties. The dominant soil properties in Atlantic climates relate to soil moisture dynamics, specifically the occurrence of excess soil water. Quantifying soil functions is difficult as each soil function encompasses a set of processes which may be altered through management which could alter the delivery of another function, resulting in potentially a synergy or a trade-off between functions. Therefore, proxy-indicators are used to estimate the extent to which a soil provides the five functions. The functionality of soils worldwide is threatened by unsustainable management practices and in Europe, there are eight main threats to soil functionality.