Ammonia emission after slurry spreading: quantification and control

Abstract

This paper describes a study carried out in Brittany (Western France) of ammonia losses from surface-applied animal slurries and a laboratory study of the ways of reducing these losses. The experiments were conducted on grass, stubble and arable land using wind tunnels to calculate the total ammoniacal nitrogen (TAN) lost from an experimental plot (1m2). The tests carried out in four departments in Brittany in 1993 revealed that the ammonia losses (NH3) varied between 5% and 63% of the total ammoniacal nitrogen (NH4+) applied in the slurry. On average, 72% of the losses occurred within the first 12 hours after spreading. Significant correlation was found between the ammonia losses (as a percentage of TAN applied) and mean air temperature and the nitrogen rate applied (kg of N-NH4+ per ha). Laboratory tests in a measurement cell revealed that prior acidification of the slurry and the addition of calcium chloride (CaCl2, 2H2O) gave an 85% reduction in the ammonia lost.