A centrifugal broadcast seeder is shown in Figure 9.1. The seed is metered from a hopper through a variable orifice. An agitator is provided above the orifice to prevent bridging of the seed over the gate and to assure continuous feeding. Sometimes a fluted wheel is used to meter the seed. The metered seed drops onto a spinning diskthat accelerates and throws it, usually horizontally. The width of coverage depends upon the size, shape, and density of the seeds. Two counter-rotating spinning disks may be used to increase the width of coverage. The seeding rate is controlled by the size of the gate opening, the speed of travel, and the width of coverage. Centrifugal broadcasters are flexible in that they can be used for broadcasting seed, dry fertilizer or pesticides, or other granular materials. After broadcast seeding, a secondary tillage operation may be performed to cover the seeds with soil.
Figure 9.1 – A centrifugal broadcast seeder
