Soil texture effects on the transport of phosphorus from agricultural land in river deltas of Northern Belgium, The Netherlands and North-West Germany

The loss of phosphorus (P) from agricultural soils can lead to serious eutrophication of surface water. Within the large river delta areas in Northern Belgium, The Netherlands and North-West Germany, a number of representative soil textures are found (sandy, peaty and clayey soils), each with its own specific combination of pathways for P loss. Based on a literature review, this paper describes for these areas the main eutrophication issues and the factors affecting P loss from these agricultural soils. Aspects of P input, legislation and water quality are discussed. On sandy soils, intensive animal production systems have led to the localized build-up of P in the soil profile with subsequent leaching to shallow groundwaters, and seepage into surface waters. Regulations for production and application of manure on these soils have led to improvements in surface water quality in the last decade, but P concentrations are still too high to maintain satisfactory ecological standards in water. On peat soils, the mineralization of organic matter in the topsoil or in the subsoil can release large amounts of P, leading to high concentrations of P in surface water. However, large P losses can also occur in seepage water from peat deposits in marine sediments containing easily-soluble calcareous P minerals. On clays, incidental losses of P are dominant: surface runoff or preferential flow can lead to loss of freshly applied P, even from soils that are known to have a large retention capacity for P.