How should the Zakah, due on a land`s produce, be calculated in light of the agreements concluded between farmers and owners of agricultural lands?

I`m a trader and I lease a citrus farm for five years in return for (1000)JDs per year, and I make (20000)JDs as annual profit. However, I pay for expenses such as fertilizers, security, irrigation, pesticide, and the like. Could you clarify the amount of Zakah due on me, and whether I should deduct the costs before I calculate the Zakah or not?

How should I calculate the Zakah on wheat?

What are the crops liable for Zakah, and what is the way to calculate their Nissab (minimum amount liable for Zakah)? And is it permissible to pay their Zakah in cash?