Reducing N and K leaching from grassland: slurry applied by spreading or injecting?

There is a need for fertilization practices that minimize nutrient leaching in Estonia, because average annual precipitation exceeds evaporation considerably. The objective of the study was to compare two slurry application methods, injecting and spreading, in terms of influence on the leaching of nitrogen (N) and potassium (K) from grassland. Mini-lysimeters filled with loamy sand soil embedded in three swards (three-species grass mixture, grasses mixture with white clover, and grasses mixture with lucerne) were used. Three annual nitrogen rates (60, 120, 180 kg ha(-1)) in conjunction with the two slurry application methods (injecting and spreading) were applied. Percolated water quantities, N and K content in leachate and the sward yield were measured. Leaching of N was significantly (P < 0.05) lower in the instance of slurry injection. K leaching was similar for both slurry application methods. Injection reduced N leaching only from grasses mixed with white clover sward. It can be concluded that slurry application method influenced only leaching of N. The botanical composition of the sward impacts the significance of application method influence on N leaching.