There are two publicly traded farmland REITs: FPI and LAND. I used to own both, and have sold out of my positions on recent strength in the units.
We can have a long discussion about the quality of management at these two REITs (somewhat lacking), but the bottom line is that these REITs are really a play on land appreciation.
Right now, LAND's self reported Net Asset Value is under $13 per share. They shares are trading just short of $24. They even caught a couple upgrades this week after earnings release. Let's say there's a time lag in how appreciation makes it into the NAV calculation (LAND appraises their properties regularly). The recent spike in commodity prices doesn't impact LAND that much, because most of their land is in specialty crops, not commodity crops. Let's say that maybe there's still some hidden value in those shares. But there is no way the NAV is $24. If you own it, sell it. I'd short it if it wasn't a real asset stock, but somehow, shorting land seems like a bad idea in general.
FPI is different, because they are primarily commodity crops. They are trading right at NAV (they don't calculate it, but they give you the data to calculate it yourself). There's probably some upside in their NAV as it is likely a little understated given what is happening to farmland prices in the Midwest. But the big upside is mostly gone. It traded up from 5 to 13 in the last year. It was a steal at 5. Not at 13.
My two cents...