The link below explains and allows you to search the Freeholders' Records of Northern Ireland
Freeholders’ records provide a range of information about land ownership and may contain all or some of the following:
Name of freeholder, Address of freeholder, Location of freehold, Description of freehold, Name of landlord, Address of landlord, Value of freehold, Names of other lives, Date and place of freeholder’s registration, Occupation of freeholder, Religion of freeholder.
http://www.proni.gov.uk/index/search_the_archives/freeholders_records.htm