The curse on the earth (Genesis 3:17–19) is made heavier for Cain. Literally it says: the ground will no longer give you its strength.
That which the ground is strong in, it will withhold from you. Cain does not have to starve, but he has to be satisfied with by-products.
12 Quand tu cultiveras le sol, il ne te donnera plus sa richesse. Tu seras errant et vagabond sur la terre.