Longbyt, that's brilliant - thanks so much.
Hmmm... so there is a basic federal law governing landwirtschaftliche Pacht:
"
Wird der Pachtgegenstand veräussert oder dem Verpächter im Schuldbetreibungs-
oder Konkursverfahren entzogen, so tritt der Erwerber in den Pachtvertrag ein.
(Art. 14 LPG). Ausnahmen sind in Art. 15 LPG enthalten."
So a Pacht agreement does indeed survive a change of ownership, with a few exceptions.
If a new owner does not want to continue the Pacht arrangement, notice has to be given within 3 months of the sale - and the Kundigungfrist is a minimum of 1 year from the usual spring or autumn termination period. However, the tenant farmer has 30 days from receiving notice to contest it. A judge can extend the lease for anywhere from 6 months to two years if terminating the contract would result in a hardship for the tenant, or if the new owner's interest in the land is not justified.
A tenant farmer who has had the land for at least 6 years also retains right of first refusal on the land - so until that is offered and refused a new buyer could be in for some surprises.
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Spoke with a colleague who is a lawyer - albeit a financial type, admittedly not an expert in Landwirtschaft issues - and he said off the cuff:
That the agreement is verbal, not a written Pacht contract, makes things complicated, but...
In the case of a dispute, the right of a long standing tenant to continue running his chicken operation i.e., pursue his livelihood, will trump my right to raise my herd o' collies on my land. In fact, if my collies proved distressing to the chickens, the tenant might have the right to demand that I get rid of my mutts.
If a case went to court, both law and public opinion are usually on the side of the local farmer, not the furriner/city slicker who is trying to make changes to a long standing way of life.
Bottom line advice: Tread carefully.
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Alarm bells clanging incessantly now.... back to the drawing board...
Thanks for the help, one and all.