Baulking

Up jump half-a-dozen off the logs and baulkings, where they have been squatting, doubled up knee to nose, after the fashion of their class; and a volley of execrations, like a storm of grape, almost blows the two offenders off the wall.

I have seldom experienced such trying bafflings and baulkings of purpose.

What he meant was that in the old days a root-field would receive three or four ploughings in addition to the necessary baulkings.