Sentence:  All day long his axe rang through the frosty air as he felled saplings for the fence and stripped them from fuel for the “<WSD>niggering</WSD>” fires. 
Meaning of the word marked with <WSD> tags:  To clear land by laying light pieces of round timber across the trunks of the trees and setting fire to them at the point of contact, by which means the trees are slowly burned through.