Halting the Upward Trend in Soluble Phosphorus Transported from a Grassland Catchment
- R. V. Smith *a,
- S. D. Lennoxb and
- J. S. Baileya
An upward trend in soluble reactive phosphorus (SRP) concentrations in Northern Ireland rivers leading to increased eutrophication has been reported for the last two decades. To identify if a similar trend could be observed in land drainage waters SRP and other P fractions were measured weekly from 1989 to 1997 in land drainage from a 9-ha grassland catchment in Northern Ireland that had a mean P surplus applied of 23.4 kg P ha−1 yr−1 Regressions of annual median concentrations of P fractions in land drainage waters against time for 1989 through to 1997 showed significant increases of SRP and soluble unreactive phosphorus (SUP) of 2.4 and 1.2 μg P L−1 yr−1, respectively. However, the annual flow-weighted concentrations and loads of all P fractions did not show significant increases with time. During the period 1998–2000 a change of management was introduced when only maintenance dressings of P were applied to the catchment according to Ministry of Agriculture, Fisheries and Food guidelines. This resulted in significant reductions in SRP concentrations in 2000 compared with 1997.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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