When you work the ground, it will no longer yield its crops for you. You will be a restless wanderer on the earth. This is the first time that we see the temporal effects on an individual for his sin. This was a specific judgment on Cain for his sin. The judgment was a personal judgment against Cain.
Sin Says that Life Is Unfair.
As we look at Cain we do not see his anger diminishing. We see an individual that anger consumes. There is no repentance, and the anger only deepens. Notice that he is angry about his circumstances. So he blames God for the harsh judgment.