The sickle-bar mower is like a giant hedge trimmer that sticks out to the side of the tractor, with a set of sharp spinning knives for cutting off hay just above ground level. Unlike some other tractor attachments, this one is powered by the tractor itself. It uses a power take off (PTO), which is basically a shaft that takes the tractor's engine power and transfers it to the attachment rather than carrying its own motor. Given the position of the blades (low and out to the side), the sickle-bar mower can be damaged by rocks, saplings, or hitting a tree or fence post.
Disc mowers are also used to cut hay at or near the ground level with spinning discs. If the hay is to be harvested and used later, disc mowers are often the attachment called on to do the cutting. Like the sickle-bar mower, disc mowers are powered by the PTO rather than having an on-board, self-contained power source.
Home and garden tractors get used most often for mowing and landscaping, so we'll take a look at the variety of popular attachments for these chores next.