Odour emission rates from manure treatment/storage systems.

The effects of agitation, liquid-only manure, depth and time on odour emission rates were investigated. Manure storage tanks were filled to incremental depths every two weeks. At each depth odour samples were collected twice. The second sample was collected seven days after the first. Odour concentration was measured with an olfactometer. Three different pig-manure treatments were investigated. In one treatment, slurry manure in a storage tank was agitated before and during odour sampling. In a second treatment, the settlable solids in manure were removed gravimetrically over 24 hours and liquid manure was pumped to a storage tank. In the third treatment (control), odour samples were collected from unseparated and undisturbed slurry manure. Overall, the odour emission rates in the agitated manure treatment ranged between 0.39 and 1.02 ou s(-1) m(-2), increased with depth and decreased with time, i.e. after seven days at each depth. In the liquid-only manure treatment, the emission rates ranged between 0.09 and 0.69 ou s(-1) m(-2), increased with depth but the effect of time was not evident. In the control treatment, the emission rates ranged between 0.20 and 0.66 ou s(-1) m(-2) and increased with depth on the first odour sampling day but decreased with depth on the second sampling day.