All perfect praise be to Allah, The Lord of The Worlds, and may His peace and blessings be upon our Prophet Mohammad and upon all his family and companions.
According to the consensus of the Muslim scholars, wheat is among the crops liable for Zakah, as stated by Ibn al-Monther (may Allah be pleased with him ): "Scholars have agreed that Zakah is due on: wheat, barley, dates and raisins." {Al-Ijma`/pp.93}.
The condition for the liability of Zakah on wheat is reaching the Nissab (minimum amount liable for Zakah) which is five Wasqs. A Wasq equals sixty Saa`s. Accordingly, the Nissab of Zakah on wheat is (750 Kg.) in modern weights. In terms of modern measurements, Dar Al-Ma`arif Al-Islamia estimated one Saa` for three liters, and so the Nissab of Zakah on crops and fruits is (900) liters, {Al-Fiqh al-Manhaji}.
In conclusion, if your (asker) harvest reaches the afore Nissab then it is liable for Zakah. One-tenth the production should be given for Zakah if the crop is watered naturally and one-twentieth if it is watered with equipments or requires expenses of transportation. And Allah Knows Best.
