Effect of Inorganic Nitrogen and Cow Slurry on Yield and Nitrogen Losses in a Natural Pasture in the Basque Country (Spain)

Inappropriate use of fertilisers can cause large losses of nitrogen (N) from the system with different ecological consequences. This study tried to make a first approach to N cycling by comparing N inputs and outputs in an imperfectly drained natural grassland soil receiving different rates of N fertiliser as ammonium nitrate or cow slurry, The acetylene inhibition technique· is used for measuring denitrification, Fertiliser response and decrease in white clover (Trifolium repens) content was greater for the inorganic treatment. The highest rates of denitrification occurred when nitrate and soil water were high. Losses in the inorganic treatment were about 5 times greater than in the slurry treatment, accounting for up to 17.4% of the applied N.