Gift deed to brother's son.

In case your the guardian of him with help of local lawyer can transfer such asset in his name and get it duly registered the other option is make a WILL for the same but it will come into force only when th maker of the WILL is deceased 

You may prepare a gift deed duly stamped and registered in order to transfer the land in his favor. However, in case your brother's son is a minor, then you will have to appoint a guardian or a estate manager to look after the interest of the minor till he reaches the age of 18.