That's the theory, but forests won't grow if they've been cut down and the ground is used to grow soy.

There are big re-greening projects going on in China and Africa to try and stop the encroaching of the deserts there though (due to deforestation and agriculture). They HAVE to add forests, else they'll get the same thing that happened in the US early 1900's, the Dust Bowl where a lot of fertile ground just blew away because there was nothing holding it down.