Although relatively less use has been made of special use valuation of land in recent years, the heavier use of the valuation option in the late 1970s and early 1980s can still lead to recapture. For deaths before 1982, the potential recapture period is 15 years after the death of the decedent; full recapture occurs within the first ten years with a phaseout between 10 and 15 years. For deaths after 1981, the recapture period has been reduced to 10 years after the decedent's death (or 10- years after the commencement of "qualified use" under the two year grace period).
The key question is what events can lead to recapture.
Harl, Neil E.
"Avoiding Special Use Valuation Recapture,"
Agricultural Law Digest: Vol. 2
, Article 1.
Available at: http://lib.dr.iastate.edu/aglawdigest/vol2/iss4/1