In Genesis 5:29 Lamech prophesies that Noah will bring relief from agonizing labor that results from cursed ground. This prophecy probably refers to the Noahic covenant. That covenant placed limits on the curse’s effects on the world.
Genesis 8:21 may indicate that God will no longer intensify the curse on the ground as he did with Cain in Genesis 4 and in the Flood itself. This verse may indicate that such intensifications were not limited to these two instances. If so 8:21 may indicate that the Noahic covenant will roll back the intensification of the curse. On this interpretation 8:21 would signal the fulfillment of 5:29.
The Noahic covenant may fulfill the prophecy of 5:29 in a different way. The nature of the Noahic covenant is to set bounds on the curse so that God’s plan of redemption can be worked out in the world. The culmination of the redemption made possible by the Noahic covenant is the removal of the curse. In this way Noah plays a significant role in God’s plan to bring the earth relief from the curse.
These proposals are complementary rather than mutually exclusive.