Harvest occurs when the crop is mature. This is measured by many different factors, such as the weather, or, depending on the crop, it may be its colour. A farmer may also do a moisture test, by pinching or creasing the crop to tell if it is ready for harvest. Knowing when to harvest a crop is a science in itself. Harvesting is usually a two-stage process. First the farmer swaths and then he or she combines. Sometimes, though, swathing and combining are done in one operation by straight combining, depending on the crop and the weather. Once the farmer knows when to harvest, he or she must make a decision about how the crop will be harvested.
Harvest begins with the cutting of a standing crop. Straight combining is usually the preferred harvest method in most of the world. Warm weather during the summer harvest season means that swathing could increase the risk of crop loss in most of these regions. Harvest in western Canada, however, takes place in the fall when temperatures are cooler, and the days are shorter. There is usually a rush to get the crop under cover and swathing offers the opportunity to speed up harvest. It is in a large part because of this that swathing has been widely adopted by cereal growers.
Some recommend that approximately 25% of the canola seeds are turning brown, even though the pods are still green. This is because canola pods shatter if left too long resulting in crop losses. Certain crops, such as lentils, peas and flax, can be subjected to chemical desiccation at about 75% maturity. What this application of chemicals does is stop crop and weed growth, which results in more uniform drying from tops to bottoms of plants, throughout an entire field. The crop may then be harvested.
