Ohalos 17:3-4

Ohalos 17:3

If someone plowed over a pit full of bones, a pile of bones, a field in which a grave had been lost or a field in which a grave was found, or if one plows a field that’s not his own, or if a non-Jew plowed – in all of these cases one doesn’t create a beis hapras. This is because the rules of beis hapras don’t apply (even) to Samaritans (who are considered quasi-Jews, and therefore certainly not to full non-Jews).

Ohalos 17:4

If there’s a beis hapras over a pure field and rain washed soil down from the beis hapras to the pure field, even if it was red and it turned white, or vice versa, this doesn’t make the pure field a beis hapras.