I know the German title of the tune, Der fröhliche Landmann, but I don't know whether there are German lyrics to that tune.

The tune however, is quoted musically in Georg Kreislers (the German language Tom Lehrer) song Der Musikkritiker (the critic of music) and mentioned disparagingly in the song's line

"but I was never able to play better than this" (to an awfully played tune of the Happy farmer).

Wolfgang