Recession of phosphorus and nitrogen concentrations in tile drainage water after high poultry manure applications in two consecutive years

High application rates of poultry ( Gallus gallus domesticus ) manure can impair drainage water quality through enhanced leaching of phosphorus (P) and nitrogen (N). In two years with application rates of broiler chicken manure corresponding to 99 and 79 kg P ha −1 year −1 to a tile-drained field with loamy soil in SW Sweden, mean concentrations of dissolved reactive P (DRP) were significantly higher ( p 3 -N) in peak, base and intermediate flows occurred in the 8-year period following manure application. Mean NO 3 -N concentration in peak flows decreased approximately linearly, by 5.6 μg L −1 , for every mm of total water discharge. Thus poultry manure should not be applied in repeated high loads in order to avoid the risk of enhanced P leaching losses during subsequent peak flows. Furthermore, N leaching losses during peak and base flow conditions can persist for longer than a 5-year crop rotation and were shown here to recede at a slower relative rate than P.