The manure is moved by auger, for example, to either the front or the back. It is spread onto the land by a set of paddles, beaters, or an impeller. These spreaders have definite advantages in very thick slurries. Otherwise, farmers will likely find the cost is more than a tank spreader of the same volume. Some farmers use them to spread manure on standing row crops.
Injectors ensure that the manure is worked into the soil immediately.
The actual injectors are mounted either on a tool bar or directly on the 3-point hitch of the tractor. If on a tool bar, they may be installed at either the front or rear of the spreader. When mounted at the front the injectors are easily seen by the driver. It's possible to achieve more uniform depth penetration on rolling land with the front-mounted injectors. Rear-mounted injectors have the advantage of breaking up the soil in the wheel tracks.