How is the Zakat calculated for a barley crop irrigated by rainwater, knowing that its yield ranges from 10 to 20 quintals per 100 kilograms of seeds, and the crop sometimes gets damaged before harvest?

For Zakat (definition) on crops, the passing of a full year (hawl) is not a condition. Rather, it is contingent upon reaching the nisab (definition), which is five wasaq, meaning approximately 300 sa' or 672 kg of good quality wheat. The amount due is one-tenth of the yield if irrigated without effort (such as by rain or rivers), and one-half of one-tenth if irrigated with effort (such as by waterwheels or pumps).