Air samples have been taken during or after manure spreading to realize olfactometry measurements and determine odour emission. The threshold value was evaluated and expressed as OU/m3. Compared to pig slurry landspreading with a vacuum tanker spreading directly on soil (VT), ploughing in manure immediately after spreading has reduced odour emission by 84%, deep injection reduced odour emission by 73%, shallow injection lower emission by 53% and low trajectory spreader with trailing hoses reduced odour emission by 38%. The following manure treatments also lowered odour emission compared to untreated manure even when using the VT application technique: 86% odour emission reduction for aerobic treatment, 84% for anaerobic treatment and 34% for mechanical separation. Crude protein-reduced diets could also have an impact on odour reduction as those diets lower the concentrations of odorous compounds in the slurry.

Odour emission can be reduced using different spreading techniques. This publication gives those reductions. No information is given on the combined effect of the spreading technique and the use of crude protein-reduced diets.