Rapid incidental phosphorus transfers from grassland.
In Britain, frequent rainfall means that there is a high potential for rapid, direct (incidental) losses of phosphorus (P) to occur after fertilizer or manure application. However, despite the known contribution of P to the eutrophication of water bodies in Britain, such incidental transfers have received little experimental attention. To rectify this, we used lysimeter plots (each 3 x 10 m) to investigate incidental transfers in a composite of overland and lateral subsurface flow (0-27 cm) following the application of different P sources. The treatments used were triple super phosphate (TSP), dairy slurry (Slurry), an equal mix of TSP plus slurry (TSP + Slurry), and no P (Zero P). The treatments were applied to wet soil at a rate of 29 kg ha(-1). In the following 169 h, 48.8 mm rainfall (intensity < or =3 mm h(-1)) resulted in total phosphorus (TP) exports between 1.8 and 2.3 kg ha(-1). A single 4-h period (with overland flow) accounted for 33 to 46% of overall loads from the P-amended treatments. Concentrations in discharge from TSP + Slurry and TSP peaked at 11000 microg TP L(-1) (67-68% as reactive P < 0.45 microm (RP<0.45). Slurry peaked at 7000 microg TP L(-1), 66% as particulate TP (>0.45 microm) and 20% as RP<0.45. Even in subsurface flow, concentrations exceeded 3000 microg TP L(-1) for all P-amended treatments. Incidental TP concentrations in plot discharge were up to 110-fold higher than those considered eutrophic in inland waters. We suggest that targeting short-term management decisions for P applications is the most immediately viable method to mitigate P loss and benefit the environment.
Preedy
N
N
Institute of Grassland and Environmental Research, North Wyke, Devon, UK. neil.preedy@bbsrc.ac.uk
McTiernan
K
K
Matthews
R
R
Heathwaite
L
L
Haygarth
P
P
D001682:Biological Availability; D017753:Ecosystem; D004784:Environmental Monitoring; D005068:Eutrophication; D005308:Fertilizers; D008372:Manure; D010758:Phosphorus / Q000493:pharmacokinetics*; D006109:Poaceae; D011891:Rain; D012989:Soil Pollutants / Q000032:analysis*; D014872:Water Movements; D014873:Water Pollutants / Q000032:analysis*
D005308:Fertilizers; D008372:Manure; D012989:Soil Pollutants; D014873:Water Pollutants; D010758:Phosphorus