Winnowing is restricted to agriculture alone?

No, winnowing is not restricted to agriculture alone. Winnowing is a process of separating components of a mixture by allowing the lighter components to be carried away by air or other means, leaving behind the heavier components. While winnowing is commonly used in agriculture for separating grain from chaff or other debris, the process can be applied in other fields as well.

For example, winnowing can be used in the food industry for separating shells or husks from nuts or seeds, in the pharmaceutical industry for separating impurities from drugs, or in the mining industry for separating minerals from rocks or dirt. In addition, winnowing can be used in a figurative sense to describe the process of separating and selecting the most important or valuable parts from a larger set of data or information.