If by the expression 'for investment' the questioner means for the purpose of trading and hopes that the price of the land will increase and then he will sell it, in this case Zakat has to be paid on this land as it is a tradable item. So Zakat has to be paid on it on the following two conditions:

1)     Its price should be at the level of the minimum amount liable for Zakat, which is the value of 85 grams of gold by itself or with other money added to it or other tradable items.

2)     A whole lunar year should have elapsed on the money with which you bought the land.

If it reaches the minimum amount liable for Zakat and a whole lunar year elapses on the amount of money with which you bought the land, then Zakat has to be paid on it, which is 2.5% when it is due. If you rent this land before you sell it, Zakat has to be paid on the rent money when a whole lunar year elapses and if it reaches the minimum amount liable for Zakat by itself or with other money on which Zakat is due.

However, if by 'for investment' the questioner means in order to rent it and benefit from its profit, and did not buy the land for purpose of sale, then in this case Zakat does not have to be paid on the value of the land, but just on its profit if it reaches the minimum amount liable for Zakat by itself or with other money added to it, or gold or silver, or other tradable items and a whole lunar year elapses. 

Allaah knows best.