How Do Farmers Sift Wheat?
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Manual Threshing
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Manual threshing
The first step in process of sifting wheat is to loosen the chaff from the edible grain, which is called threshing. The old fashioned way to do this is to spread the wheat onto a floor made from stone, concrete or tamped earth and to beat it with a flail. This is no longer done in the developed world, but in some places where machines are expensive and human labor is not, manual threshing is still common.
Winnowing
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The next step is called winnowing, where the loosened chaff is removed from the grain. The old fashioned way of doing this was to throw the grain in the air, where the lighter chaff would be blown off by even a decent breeze. The heavier grains would fall back to the ground below where they were thrown.
Combines
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A combine in action.
In the developed world, threshing and winnowing is done in a machine called a combine. Combines are called that because they combine multiple farm tasks into one process, in this case harvesting and threshing. These machines are one of the great workhorses of industrialized agriculture, allowing one man to do the work formerly done by many. The combine will drive through the fields, cutting and scooping the wheat into a machine that separates it from the stalk and then the husk. The grain is fed into a group of horizontal cylinders called rasp bars, which guides the grain upwards through grates and sieves, combining threshing and winnowing into one short process. The finished grain is then dumped into a trailer or following truck.
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