Who is the owner of extra land not mentioned in sale deed

THe person who is in posession can utilize it but no one can be owner as when correction or demarcation will be done the land will be adjusted to its original owner

Officially you are the owner to the extent of what your property document states, the surplus land surrounding your property is not yours though you may be in possession, hence while making a claim for it, you must establish that you were in possession of the same for more than 12 years to perfect the title by adverse possession, consult a local lawyer and move further as per his further advise.

first as per your query what documents you have to prove that you registered document has less land site because before going to fight for legal you have to gather all the evidencial documents to prove that that the actually your land area is say 10 and in your sale deed is 8 the difference 2 to prove you should have the evidence 

okay you can gather the neighour land sale deed and check through his sale deed the difference of land his is and yours and you can file for demarcation for this you have to approach a sub registrar office of that land area and give a application and if he has not taken any action then you have to file a civil suit to order the registrar to make demarcation and rectify the difference in land area from encrochers