Explain:
another method of threshing is to pull the stalks through a saw-toothed frame resembling a comb that is placed over a box to catch the separated grains
Answers
Answer:
Threshing is the process of separation of grain from the stalk on which it develops and from the chaff or unit that covers it. In the process, the edible part of the crop is loosened but not the fiber part. It is done after harvesting and before winnowing. The technique that was used in old times was striking the harvested ears of grain with a thrash and this was done manually. Alternatively, horses, donkeys or bulls trod out the grain from stalks. After this, the straw was gathered and raked away while the grains were winnowed to remove the debris. During winnowing, the air current blew away the light weighed waste particles leaving behind the heavy grain particles. But the whole process was tedious.
Later in the seventies, Andrew Meikle contrived a threshing machine. Piles of grain were sustained into a spinning chamber furnished with wooden mixers. The machine had a saw-tooth like drum to rake away the free straw and pushed the remaining waste and grain through a strainer into a set of rollers that further isolated the chaff from the grain before winnowing. The working principle of Meikles's machine has been used in all threshing machines including the advanced self-moved combines. Combine harvesters do the harvesting, threshing and winnowing.
Threshing was usually carried out in an isolated plot of land called threshing floor. Some threshing floor were flattened circular or paved surface (outdoor) but usually in a small-scale farming, the floor used to be a stone or a wooden plank. Outdoor floors were a common property used by a whole village. But unfortunately, modern machines and technologies outsourced floor.
Threshing and Winnowing
Threshing is the most critical kernel harvester feature. Grain loss and harvest destruction contribute greatly to the philosophy and techniques of threshing. Four forms of threshing principles are available: scratching, scraping, combing, and grinding.
Grain loss may be called a function of peripheral velocity and affecting touch pattern. Grain loss can be known to be a feature of rasp bar touch patterns. Grain loss resulting from cleaning and separation was substantially reduced in the subsequent combing threshing process.
The name given to the method of extracting the grain from the chaff is Winnowing. This is the move after a threshing (the method of loosening the chaff). Winnowing also requires ventilation – since the grain is often thicker than the chaff, a gentle wind is generally enough to blow away the chaff, whereas the grain is left in place.