Is zakat obligatory on the remaining uninvested plot of land, and how is zakat calculated for it and for the period prior to its division, and how is the zakat calculation for a grape project (1400 vines) organized?

If a person acquires land without intending it for trade, then zakat is not obligatory on it. The same applies if it is inherited. However, if they intend it for trade, zakat is not obligatory on it until it is sold and its price, if it reaches the nisab, has been held for a full year. If it is rented out, then zakat is obligatory on its rent if a full year passes and it reaches the nisab.

As for zakat on grapes, it becomes obligatory if the dried yield reaches the nisab (five wasqs). Half of one-tenth is given if it was irrigated by machinery, and a full one-tenth if it was irrigated by rainwater. Zakat is given from the grapes themselves before they are sold. The time zakat becomes obligatory on black grapes is when their blackness appears, and on white grapes when they develop sweet water or show a yellowish tint.