Alms Tax: The Amount of Zakat for Mixed Methods of Irrigation

Practical Laws of Islam as per the teachings of Ayatullah Sistani

Ruling 1892

If wheat, barley, dates, or grapes are irrigated by both rain and buckets of water and suchlike, in the event that it is commonly considered that their irrigation is by means of buckets of water and suchlike, the zakat on them is one-twentieth [5%]. If it is commonly considered that their irrigation is by means of a stream or rain, then the zakat on them is one-tenth [10%]. And if it is such that it is commonly considered that their irrigation is by both means, then the zakat on them is three-fortieths [7.5%].

-Ayatullah Sistani, Practical Laws of Islam, Alms Tax (Zakat)