I have land in which I grow wheat and barley. Is zakat obligatory on them?

Zakat (definition) is obligatory on grains and fruits if they reach the nisab (definition), which is five awsuq, approximately 612 kilograms. Wheat and barley are among the types subject to zakat. If the yield of wheat or barley alone reaches the nisab, zakat becomes obligatory on it. However, if neither reaches the nisab independently, one cannot be added to the other to complete the nisab, due to the difference in their species. Varieties of the same species are combined to complete the nisab, such as different types of dates or different types of wheat, but different species are not combined.