Iowa Farmland Bubble?

The Dec 5 Des Moines Sunday Register banner headline read: Why Farmland is Skyrocketing.  The Register reports that due to rising corn (maize) prices,  Iowa farmland is now changing hands at prices  over $8,000 per acre,  and some parcels have sold for up to $14,000.   They suggest that a speculative bubble may be building.   This would not be the first time this has occurred in Iowa--it also happened in the early 1920s and in the late 1970s.  Both times, the inevitable crash resulted in a severe depression for rural counties.   The nationwide recession in the U.S. today is probably less severe than that endured by most rural Iowa counties in the 1980s, after the farmland price collapse at the beginning of that decade.  Are we doing this again?
    Between 1972 and 1979,  Iowa farmland climbed from  $2,495 per acre to a peak of $5,711.  Then by 1986 it had crashed to only $1, 519.   By 2000, It had taken took 14 years to climb back to $2,291 (still less than it had been 28 years earlier.)  But by 2009 it had nearly doubled to 4371, and in just one more year it has doubled again.