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

Ammonia losses were investigated from broadcast, band-spread and injected untreated cattle slurry, broadcast aerated slurry and broadcast separated slurry (liquid fraction). The slurries were applied on ley after the first cut at an application rate of 33 to 62 Mg ha(-1) including about 80 kg ha ammoniacal nitrogen. Slurries were analysed and ammonia emission was measured with a micrometeorological chamber method on the day of application and on the following two days. Separation lowered the dry matter content of slurries by an average of 37% but aeration had no significant effect. Aeration reduced the ammoniacal nitrogen content by an average of 12%. About half of the ammoniacal nitrogen of broadcast slurries was lost through ammonia volatilization, but injection of slurry into the ground prevented ammonia losses almost totally. Band spreading retarded ammonia volatilization on the day of application, but total emissions were not significantly different from broadcast slurry. Ammonia volatilization from neither aerated nor separated slurry differed significantly from broadcast untreated slurry. However, in some cases the volatilization of ammonia was lower from the separated slurry, whereas the highest volatilization was measured from aerated slurry. Injection of slurry into the ground proved to be far more effective in preventing ammonia emission than the reduction of either surface area or dry matter content of surface applied slurry.