Hmm, w.r.t to the agrarian social structure, there was a guy who said that librelization has had a positive effect on agriculture, brought in better infra, more connectivity etc.
You can say it will lead to the spurt of the new, educated farmers/entrepreneurs, those who do reverse migration, from cities to towns. Many thinkers talked about it during green revo. I dont remember names, if you want i can check them up. But on the top of my head i will say the guy who wrote the book "where have all the farmers(?) gone?" and most of the marxist thinkers like ashok rudra and all.
He even gave a character desc. of this new farmer. most sociological studies were on the impact of green revolution and the effect on urbanization etc. which is amplified by FDI. So, maybe you can use those studies.
Plus many others, who mostly classified them into big/small/new educated farmers. The big farmers already no not need middle men. So, FDI will benefit the small farmers, as they are the ones most plagued by middle men. This is just a guess, have no concrete proof of this.
As for the negative effects, you can say it can again lead to usurpation up the big landowners, as said by gail omvedt. But i dont think there are any major negative effect on the agrarian social structure. Maybe on the rural social structure, but not sure about agrarian. There might be on other things, like loss of business for convenience stores. BTW, there was a term for these small shops, like some xxx and xxx store. Do you remember?
Just cooking something up. If you have any ideas, please do share.