Definition of "landfast"

There is an economy in the matter of breakages and repairs, for if the plough should be brought up upon a landfast rock, instead of the brunt coming simply on the draught rope, which would either snap or pull the framework of the plough to pieces, it is, through the pull of the one drum upon the other, immediately spread all over the field wherever the rope goes […]

1862, Arthur Young, John Chalmers Morton, The Farmer's Calendar