Billy---one method of planning ahead is to create an Irrevocable Life Insurance Trust (ILIT) funded with a life insurance policy for the amount of the potential Estate Tax due at death.
If the tax due is $1,000,000 the land owners heirs would have tax free cash from the life policy to pay the tax, in essence,preserving the farm asset....in the family.
Of course, the deceased farm owner would need to have the foresight to buy the life policy before death, be in good enough health to get the policy, and have the money to be able to pay the premium on the policy.
The owner could also sell the farm before he dies, and spend all the money before the kids or the gov. get what's left over after the initial tax hit.