1. Land "lies fallow" in order to replenish nutrients in the soil. If you keep planting the same field over and over again, you will wreck its productivity.
2. The poor quality soil (often the result of overprinting) cannot be used to grow biofuels unless you plan on dumping tons of fertilizers on it. Those fertilizers are often made from petroleum in the first place.

So what, exactly, are we gaining here?