Presumptive ownership (chazakah)
is only valid in the absence of the alleged owner's protest. If the
owner protests at least once in three years, the occupant is put on
notice, and his chazakah is ineffective. In other words, if the
occupant really bought the field, he should keep the deed, and his
negligence to do so in inexcusable in the face of a protest, thus his
three years of occupancy don't help.