Chrispy

I have a small farm south of the Loire,which has more land attached than I can manage at the moment. I have therefore continued the same arrangement as the previous owner, and allowed a local farmer free use the land. This works well for him as the land is unfenced and sits alongside his own fields and he has helped me with his digger. A very good arrangement! My one concern is that I could lose ownership of the land if has continuous use of the land for a number of years.Does anyone know how this law works and what is the period ? Could I protect myself by instucting him to cease using the land for one year before the crutial period ? Thanks