This spread pattern could be a wide band extending on either side of the line of travel. Alternatively, the pattern may be out to one side only. Farmers wanting to spread manure on standing row crops may prefer to use either drop pipes or injectors instead of broadcasting the manure onto the crop. A drop pipe system consists usually of two to four pipes which ride along just above ground level. These distribute the manure in strips between the rows.
Injectors are basically the same except that the manure is knifed directly into the soil.
Injectors may be mounted at either the front or rear of the spreader, while drop pipes are almost always mounted at the rear. The gravity unloading spreaders rely on the weight of the manure to empty them. The fluid head at the outlet will gradually decrease as the spreader empties. Therefore, the rate of flow of manure will decrease accordingly. The manure may be deflected into a narrow band at the rear of the spreader, or it may be directed through drop pipes.