I have a piece of land where rice is cultivated. I lend this to poor farmer on the condition of giving me 480 kg rice per year. Is it Halal? If not, What should I do?

All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and messenger.

The case which you mentioned in the question is considered a lease transaction whereby land is leased in return for some of its produce. Since, the amount of produce is determined, which is 480 kg as you mentioned in the question, then this is permissible according to the view of the majority of the scholars.

A Fatwa from Ibn Taymiyyah reads: “With regard to leasing land in return for some of its produce, like cultivating the land with wheat or barley, in return for a specific amount of wheat or barley to be given to the land owner, then this is also permissible according to the more correct narrations from Ahmed, which is also the view of Abu Haneefah and Ash-Shaafi‘i. Ahmad's other narration, however, suggests that this transaction is forbidden, which is also the view of Maalik .”

The Fiqh Encyclopedia reads: “If a person rents a piece of land in return for some known food from its produce, like renting it in return for wheat, while it has been sown with wheat, then Imaam Maalik said: "It is not permissible because of the Hadeeth that we have already mentioned." This opinion was also narrated from Ahmad. Abu Haneefah and Shaafi‘i, which is also a narration by Ahmad, said: “It is permissible, because what is permissible to be rented in return for other than food is permissible to be rented for food, as in the case of houses.”  

Allaah Knows best.