The factors at work:
- farmers built up their net worth during the boom better than they did in the 70's
- interest rates now are low, in the 80's high
- lending on real estate was more rational
- better safety net due to more crop insurance coverage.
I'd also observe there are a lot fewer farmers today than in the 80's, which IMHO reduces the likelihood of any one farmer going bust--there's fewer marginal players in the game.