means the high ridge between furrows (Anglo-Saxon balca, a beam, a ridge); hence a rising ground.
A balk of timber
is a beam running across the ceiling, etc., like a ridge. As the
balk is the part not cut by the plough, therefore “to balk” means to
leave untouched, or to disappoint.
To make a balk.
To miss a part of the field in ploughing. Hence to disappoint, to
To make a balk of good ground
To throw away a good chance.
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894