N.J. Stat. Ann. § 54:4-23.16

Separation or split off of a part of the land which is being valued, assessed and taxed under this act, either by conveyance or other action of the owner of such land, for a use other than agricultural or horticultural, shall subject the land so separated to liability for the roll-back taxes applicable thereto, but shall not impair the right of the remaining land to continuance of valuation, assessment and taxation hereunder, provided it meets the 5-acre minimum requirement and such other conditions of this act as may be applicable.