Effect of treatment and application technique of cattle slurry on its utilization by ley: I. Slurry properties and ammonia volatilization

Abstract

Ammonia losses were investigated from broadcast, band-spread andinjected untreated cattle slurry, broadcast aerated slurry and broadcastseparated slurry (liquid fraction). The slurries were applied on ley after thefirst cut at an application rate of 33 to 62 Mgha−1 including about 80 kgha−1 ammoniacal nitrogen. Slurries were analysed andammonia emission was measured with a micrometeorological chamber method on theday of application and on the following two days. Separation lowered the drymatter content of slurries by an average of 37% but aeration had no significanteffect. Aeration reduced the ammoniacal nitrogen content by an average of 12%.About half of the ammoniacal nitrogen of broadcast slurries was lost throughammonia volatilization, but injection of slurry into the ground preventedammonia losses almost totally. Band spreading retarded ammonia volatilizationonthe day of application, but total emissions were not significantly differentfrom broadcast slurry. Ammonia volatilization from neither aerated norseparatedslurry differed significantly from broadcast untreated slurry. However, in somecases the volatilization of ammonia was lower from the separated slurry,whereasthe highest volatilization was measured from aerated slurry. Injection ofslurryinto the ground proved to be far more effective in preventing ammonia emissionthan the reduction of either surface area or dry matter content of surfaceapplied slurry.