Swathing

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 swather's job is to pick up the swath, and separate the grain from the straw. The straw is usually returned to the soil, continuing a cycle of fertilizing for another harvest. 

Moisture content of the crop's seed helps to determine when swathing should occur. Wheat and oats are swathed when moisture content is 35 percent, barley is swathed when the content is between 35 and 40 percent and rye is cut when moisture is up to 45 percent. Moisture content can be determined by looking at the kernels and with a "touch" test; kernels should be fairly firm, but can be indented with a finger or thumbnail. 

The swath may be self-propelled, tractor-mounted or tractor-pulled. Unless straight combining is being done, then swathing happens before any combining. Some swathing implements are used for double swathing, where they can lay one swath beside the previous swath. Where crops are light, this reduces pick-up 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 presses the swath into the stubble and protects the swath against the effects of the wind. Many operating techniques as well as the type of swather used affect 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. Furthermore, losses due to insect, hail or frost damage may be reduced.