We need to be careful about reading this story and assuming that it has a literal meaning. This story is an excellent example of an allegory, which is a tale which operates on both the literal and the symbolic level. The characters and events of an allegory can be therefore understood to both stand for what they are, but also for abstract principles which they are shown to represent. Let us note the role that the devil plays at the beginning of the story before working out the abstract principle that he represents. Note what the devil says, having overheard Pahom's plea for more land:
"All right," thought the Devil. "We will have a tussle. I'll give you land enough; and by menas of that land I will get you into my power."
The "tussle" between Pahom and the devil takes the form of Pahom's constant dissatisfaction with the ever-increasing amounts of land he manages to obtain. His greed is shown to be provoked by the devil, which therefore indicates that we can associate the devil with representing the abstract principle of human weakness. If we think of Pahom as representing the human soul, a kind of arena where humanity can be tested, this supports the representation of the devil.
In my opinion, the devil in “How Much Land Does a Man Need” is the manifestation of Pahom’s greed. In the beginning, the reader is exposed to Pahom as a peasant in the village. His family did not enjoy the benefits of material wealth, and they had to toil in laborious tasks to make ends meets. During the argument between the sisters, Pahom intervenes in support of his wife and asserts that access to more land is the only barrier to a peasant’s success and prosperity. There might be some truth in his assertions; however, Pahom does not consider that with access to land comes the urge to acquire more of it. Pahom’s greed, in the form of the devil, haunts him and forces him to chase more land. He fails to settle down and nurture what he has already acquired. His focus is always on the next grand opportunity. In the end, his insatiable greed leads him to his grave.
The story also reminds the reader that “a bird in the hand is worth two in the bush.”