What is the relationship of a man and land as depicted in the story “How Much Land Does a Man Need?”

"How much Land does a Man Need" is a story about land-greed. From this perspective, it is not the land itself which is the problem, rather it is the rapacious greed to acquire more of it (essentially, the acquisition of wealth for its own sake), that the story condemns.
Indeed, note that the story is explicitly Christian in its set-up. In its first chapter, Pahom declares that his unhappiness is caused by his not owning enough land, and that, if he were to only own enough land, he would fear nothing, not even the Devil. The Devil hears his claim, and decides to test him on this. By granting Pahom's wish, the Devil expects to bring Pahom under his power.
This is a story about corruption, and as Pahom acquires more land, his hunger for still more land increases. He makes enemies of his neighbors, and all the while continues to seek out better prospects, always wanting more, never contenting himself with what he already has. He is given over entirely to his greed (and this, rather than the land itself, is what Tolstoy condemns. It's a warning against unrestrained excess). When we come to the story's ending, when he accepts the terms offered by the Bashkirs, that same greed will lead to his destruction.