[GeneT45]

I think the idea of fertilization is that "depleted" farm land may be rejuvenated - which seems to be working. Can you expound on how we are (irreversibly) over-utilizing land? - The article appears to me to be good news: we are more efficiently utilizing land, so a smaller area may sustain a larger (human) population. Fewer acres of indigenous flora need be displaced. No doubt that such displacement is not without impact, but short of reducing human population, efficient use of the resources we take over seems desirable.

[AngryData]

It isn't "permanently" depleted, but it takes between 75-150 years to build topsoil up to any significant thickness, sacrificing fertilizer and crop all along the way to the soil before it provides high yields that we enjoy benefit from. Short term we are growing more crops and harvesting higher yields than the soil can support, drawing out more nutrients than we are able to effectively put back into it.

What people need to remember is farmland is not just dirt. Dirt is near worthless. But top soil is an entire living ecosystem of bacteria and fungus that must be grown and takes a very long time to do so. And an organism/ecosystem has an upper limit on how fast it can grow no matter how much food and care you put into it. The topsoil on a field by itself is worth more than all the equipment, buildings, seeds, fertilizer and more combined.

Because of agricultural land contraction large agricultural businesses have been enabled to deplete the soil for short-term 10-20 year profits, sell it off for development, then buy out the smaller and more sustainable run farms that are on the edge of bankruptcy because of the unsustainable practices they cannot compete with. At some point we will run out of old farmland to keep buying up and unsustainable practices will become impossible, but not before we ruin tons of prime farmland that took 100+ years to build up and further limiting the amount and yield of sustainable agricultural practices until we spend many more decades building the soil back up.

Its like the same problem with fishing, we can gather more fish now and make greater profits now, but at the cost of severely reduced future output as we over-utilize natural processes.