Threshing and Winnowing
----------------------------

1. Separating fruits or seeds from the plants or ears is called threshing. In cereals, straw and grain are separated and in pulses seeds are separated from the pods. Threshing is followed by winnowing. Separating grain or seed from chaff is known as winnowing, Wind power is used to separate husk and grain since husk is lighter than grain or seed. Threshing is done immediately after harvest of the crop or it may be done at a later stage.

2. Threshing of cereals, millets and few pulses are done mainly by beating against stones or any other hard material or by beating with mallets or by treading under the feet or cattle or tractor tyres. Some threshers like Olpad thresher, Japanese rotary paddy thresher, rollers etc., are also used. Rollers made of stones are used to thresh grain from ears of sorghum, pearl millet, finger millet etc. The ears are spread in a circular path of one meter width with a thickness of about 20 cm. The roller is pulled with the help of a pair of bullocks over the circular path pf ears. The repeated rolling separates th seed from the ears.

3. Olpad thresher is used to threshing wheat, barley, oats etc. It consists of 20 circular discs each 45 cm in diameter and 3 mm in thickness placed 15 cm apart in three rows. The thresher is run by a pair of bullocks over the dried crop spread in a circular path on the threshing floor.

4. Japanese rotary paddy thresher consists of a threshing drum, mechanism and a supporting frame. The main parts of the machine are a wooden durum with peg-teeth all around its circumference. The diameter of the drum is about 43 cm and width may vary from 40 to 76 cm. The thresher is operated by a single person with the help of a pedal. Threshing of paddy is done by holding the bundle of sheaves against the teeth of revolving drum.