Threshing methods - Harvest and Post Harvest Operations, Crop Production | Crop Production Notes- Agricultural Engineering PDF Download

What is threshing? 

Threshing is part of the harvesting process. Threshing involves separating the grains from the straw either by impact, friction or combing action.

Why is proper and timely threshing important?

Any delay between cutting and threshing causes rapid deterioration of the grains, especially during field drying or when the crop is stacked in the field. Improper threshing can also cause high threshing and scattering losses.

The different threshing methods:

1. Foot threshing or trampling:
Use of bare feet or animals to thresh the crop which is spread on the floor. In some regions animals have been replaced by tractors.

2.Beating against a threshing rack:
The grains are separated from the straw by impact when the crop is beaten against a slatted bamboo, wooden platform or any other hard object such as a steel oil drum.

3. Pedal thresher:

Holding the crop against a threshing drum driven by a foot crank combs the grains from the straw. Because small straw chaff and foreign matter drops with the grains, cleaning is needed

4. Machine threshing
Because of the high labor requirement of manual threshing, mechanical threshers of different types and sizes are increasingly being used.

The thresher

Depending on the farming system, post-production practices and the available infrastructure, threshers come in different sizes. They range from small portable units without a cleaner such as those used in the Philippines, to large truck-mounted units such as in Thailand.
Threshing is usually done in the field, near the field or at the nearest road.
Usually, a mechanical thresher works with a drum as axial. The crop turns around the axial. (see image on the left)
The drums have "teeth" on the surface. (See below) The teeth of the pegtooth drum make the grains separate from the straw by beating it.