A swath is a cut grain. The strip of cut grain is on top of the stubble. The stubble holds the swath off the ground in order to allow air to circulate around the grain to dry it. The swatter's job is to pick up the swath, and separates the grain from the straw. The straw is usually returned to the soil, continuing a cycle of fertilizing for another harvest.
The swathe may be self-propelled, tractor-mounted or tractor-pulled. Unless straight combining is being done, then swathing happens before any combining. Some swathing implementations are used for double swathing, where they can lay one swath beside the previous swath. Where crops are light, this reduces pickup losses and makes better use of combine capacity and efficiency. Swathers may also have pickup reels or fingers to lift up crops that are close to the ground. With other crops like canola, or mustard, a roller behind the swather, is there to press the swath into the stubble and protect the swath against the effects of the wind. Many operating techniques as well as the type of swather used effect swathing performance.
Swathing is usually carried out before seeds are ready for actual separation from the rest of the plant. One reason a farmer may choose swathing rather than "straight" combining is because harvesting can occur earlier and select areas may be harvested giving immature plants a chance to develop further. Further, losses due to insect, hail or frost damage may be reduced.
