A good review of the odour evaluation methods is given. The magnitude method and the ranking methods were used to evaluate manure aeration and additive addition at different rates. The panel members in the first case had to give a magnitude estimation of the odour using a scale from 1 to 9 with the distilled water being assigned 1 on the scale and untreated manure being 7 on the scale. Toward the end of the testing, ranking evaluation was also done comparing only 2 samples and deciding which on is the more offensive. The ranking method appeared to be the more precise method than magnitude however ranking doesn’t give any information on the differences noticed.