Question

why does the government usually maintain a buffer stock grains ​

Answer 1

Answer:

buffer stocks are used to be maintain to supply the grains to the people of the country when there is shortage of grains or the production of the grain was very low due to any reason

Answer 2

Answer:

If any disaster come then there is the absence of food, many people don't get food properly.

So as to help those people in food the government usually maintain a buffer stock grains.

I think you have got your answer.