My father owned a piece of land out in the country. For more than 30 years ago, he let an adjacent family us it for garden. After I inherited the land in the mid-90s, I implicitly permitted them to continue. That is, I never actually talked to them, I just let them keep doing it.
Now I want to put the land on the market. It's in the country and must pass a soil test. I've been told that the garden may cause it to fail.
I left a voicemail informing them of garden's possible effect on the soil test. I asked them to remove whatever they have planted this year. I haven't talked to them or been out there yet to see if they have (I live out of town).
Do they have the right to continue to garden on land because they've done it for over 30 years? Are they the de facto owners of the land?
Consent appears to be the biggest issue here as it sounds like you and your father knew they were farming your land. Courts do not favor transfer of land by adverse possession so it is an uphill climb for them if they want to make the claim. That said, you should be gathering up evidence to prove you claim (old tax receipts showing you paid the taxes all this time, talk to witnesses of conversations between them and your dad that he would allow them to use the property, etc.) in case they decide to pursue a claim of ownership.