The blow given through the air to remove the outer covering is called winnowing.

Winnowing
Winnowing is a method used in agriculture to separate the grain from the chaff. This process helps in removing unwanted materials like dirt, dust, and straw from the grains before they are stored or used for consumption.

Process of Winnowing
- The harvested crop, such as wheat or rice, is spread out on a clean, flat surface.
- The farmer then lifts the grain and throws it into the air.
- As the grain falls back down, the lighter chaff and debris are blown away by the wind, while the heavier grain falls back to the ground.
- This repeated tossing of the grain allows for the separation of the heavier grain from the lighter chaff.

Importance of Winnowing
- Winnowing helps in cleaning the grains and removing impurities, ensuring that only the good quality grain is retained for consumption or storage.
- It also helps in increasing the shelf life of the grains by removing moisture and preventing the growth of mold or fungus.
- Additionally, winnowing helps in improving the overall quality of the crop, making it more marketable and desirable for sale.
In conclusion, winnowing is a simple yet effective method used in crop production to separate the grain from unwanted materials. It plays a crucial role in ensuring the quality and purity of the harvested crop before it is used for various purposes.