LEACHING OF LIME AND FERTILIZERS FROM A RESEEDED UPLAND PASTURE ON A STAGNOGLEY SOIL IN MID-WALES

Concentrations of nutrients were measured in drainage water from a drained but otherwise unimproved area of Molinia grassland and from a similar area following pasture improvement in Year 1 of the 4-year study. Application of lime and fertilisers to the improved area and reseeding with a grass / white clover mixture had little effect on concentrations of nitrate and ammonium-N in drainage water except for one year when nitrate concentrations were increased to a maximum of 24 mg N l(-1) for a brief period following application of nitrogen fertiliser. Concentrations of organic-N, potassium, phosphorus and calcium and the pH of water samples increased following pasture improvement and were consistently greater than corresponding values for the Molinia area. By Year 4 almost all of the potassium fertiliser applied to the reseeded area in Years 1 and 2 had been leached. In the same period, about 12% of the phosphorus fertiliser and 24% of the lime application had been leached.