Thanks for the link, very interesting read so far. Has there ever been an evaluation of the potential lifespan of land currently under cultivation? Will the former rain forest land in south America still be producing as long as land in Europe, or does it have a best before date under intensive agriculture? Or can humans with our technology and nearly limitless energy(example diesel for landscaping) reclaim any land to productivity? Given the irreplacability of food, could we ever replenish worn out soil by mining organic soil locked in permafrost and hauling it south? There are a lot of energy intensive options that weren't available to civilizations prior to the industrial revolution who relied on human/slave labor, who in turn required more food, which required greater strains on the land...... Although one could make the same argument today as we use crops to make fuel.

A topic I take very seriously considering the fast degradation I can see in our local shallow low OM clay soil in only a few generations. I believe that without a serious change, much of the soil on our own farm is already closer to the end of its productive lifestyle than the beginning.