Of the environmental changes given the highest priority within ICP Integrated Monitoring, N and S deposition have important implications for the soil chemistry. The minimum requirements of the soil chemistry subprogramme therefore reflect the acidification impacts of S and N deposition, and the eutrophication impact of N deposition.
The focus is on properties describing the acid and N status of the soil, background properties that determine soil acidity and nutrient status, parameters necessary for calculating soil chemistry pools/amounts, and those soil properties required by the various acidification and geochemical models used within IM.
Soil water chemistry is also monitored by ICP Integrated Monitoring. Acidic water percolating through the soil dissolves and weathers minerals, releasing base cations for nutrient uptake by microbes and roots alike, for seepage to deeper layers and ground water, and ultimately for outflow to rivers and lakes. Soil water is intimately coupled with the chemical and biological processes in the upper soil layers and is sensitive to both acidification and nitrogen pollution. The soil water chemistry subprogramme is therefore one of the most essential subprogrammes for understanding geohydrochemical interaction with biological effects at both plot and catchment scales.