This paper focused on evaluation of existing liquid manure application methods and equipment from an odour-related perspective. Requirements for liquid manure injection and how to select injectors and the operation parameters were also addressed. Odour levels associated with land application of liquid manure are not directly related to the
application method. That manure injection provides lower odour level than surface application is not necessarily true in some injection cases where excessive manure is exposed to the air as a result of poor injection operation or the use of an inappropriate injector. Odour levels are directly determined by the amount of manure exposed to the air and the surface area covered with exposed manure, if other conditions are the same. Injection may not reduce odour to a background level (equivalent to odour over an unmanured soil surface), even it is properly done. Odour concentration at the ground level following manure injection varies from approximately
double 18 times higher than the background value, depending on the extent of manure exposure.

The primary criterion for selecting an injector should be based on the tool capacity that must be sufficient in order to minimize exposed manure, and consequently odours. Other criteria should be also considered, such as the hose power requirement and manure distribution in soil. In grassland application, minimum soil disturbance is also an important criterion. The performance of an injector on these perspectives is not only affected by tool type, but also by injection depth and other factors. Generally, manure application to grassland was feasible using low-disturbance injection, infiltration enhancement, surface banding and sub-canopy application methods, in terms of grass
production. However, there is the potential for odour if excessive overflow-manure occurs.