It depends on the state, but even if you have a $5m exemption on inheritance, if you inherit $10m of farmland, you need cash to keep the land (or go into debt) or liquidate the land.

No federal estate tax on $10m of farm land (kicks in around $13m this year, from what I can tell—the so-called "death tax" is often framed as applying to a whole lot more people than it actually does). Further, I'm pretty sure there are ways to structure a business that'll prevent even amounts exceeding $13m from being affected—granted, that would require advance planning which may or may not have been done.

The rest would vary state by state and depend on the relation to the deceased, but I'm pretty sure it'd be $0 or negligible in most cases, on a $10m estate, for spouse or children at least, even with minimal advance preparation.

Farms in a family trust are not subject to the death event that triggers inheritance tax.