Keeping grapes in Kangina

Written by: Muzamil Shah Watandost

In some provinces of Afghanistan, gardeners have vineyards that provide their basic needs from harvesting.
Some of these gardeners store grapes in Kangina(a special pot made from mud to keep grapes in it)  and to get more benefits, they sell them at a higher price in the wenter. Besides them, some other gardeners complain about the rotting of their grapes in Kangina.
How can they keep the grapes without rotting in Kanginas for a long time?