This looks like a wild goose chase thread. Purchasing agri land in installments is not an easy task. The agri land itself is normally held by a farmer and in my experience, all of them want their funds in full and outright during sale.
So this would mean that an intermediary is holding the land with the farmer and probably trying to make a fancy margin by selling it to other prospects. This would also mean that till one pays the last installment the title will not be transferred in your name.
It is always best to buy outright land and transfer title to own name, rather than get into such schemes.