N.J. Admin. Code § 18:15-13.1
Where contiguous land in agricultural or horticultural use and in single ownership is located in more than one taxing district, compliance with the five acre minimum area requirement is determined on the basis of the total area of such land and not merely the area of the part which is located in the particular taxing district.
Example:
An application for farmland assessment covers 15 contiguous acres of land in agricultural use in single ownership; three acres are in taxing district A, the remaining 12 acres are in taxing district B. The three acres in taxing district A are deemed to meet the five-acre minimum area requirement, since it is the aggregate contiguous area, in single ownership, that determines area eligibility in such case, and not merely the area of the portion located in the individual taxing district. (See N.J.A.C. 18:15-3.2(c) )
N.J. Admin. Code § 18:15-13.1