How is zakat calculated on sugarcane whose cultivation costs 63 pounds per feddan, with a return of 57 pounds?

Zakat is not obligatory on sugarcane itself. Rather, it becomes obligatory on the money obtained from its sale, if this money reaches the nisab (minimum threshold) either on its own or when combined with other cash, gold, silver, or trade goods, and a hawl (one lunar year) has passed over it. In this case, it is subject to Zakat like gold and silver.