An overview on deficit and requirements of the Irish national soil phosphorus balance

Phosphorus (P) is an essential life-supporting nutrient for which there is no substitute. Modern farming practice and food production are supported by the application of mineral P fertiliser derived from finite mined phosphate rock. The European Union does not have indigenous mineral phosphate reserves, which poses a significant issue to food security. This research paper assesses the potential of indigenous recycled P sources to replace imported P fertiliser within the Republic of Ireland. The research is undertaken at NUTS 3 (Nomenclature of Territorial Units) regional level, the nutrient soil P requirement is established, and the extent to which the regional production of indigenous recycled P sources can offset this requirement is determined. The soil P requirement was derived from analyzing the regional soil P indexes, stocking rate and land-use. It was established that to optimise Irish agricultural production, approximately 95,500 t of P fertiliser is required by Irish agriculture per annum. Indigenous P sources were reviewed to determine their contribution to the Irish P balance; the sources included sewage sludge, dairy processing waste, and animal manures. Regional indigenous P quantities vary greatly with the South-West Region producing the largest quantity of indigenous recycled P at 42.4% of required P than the Mid-West Region only producing 22.0% of its P requirement indigenously. Sources of indigenous P also vary greatly from region to region depending on population and industry, with the highest quantity of sewage sludge being produced in the Dublin plus Mid-East Region while the greatest contributor of dairy waste is the South-West Region. In total, over 28,500 t of P is recovered from indigenous sources per annum. This indicates that approximately 30% of the national P requirement could be met by indigenous P recycling.