https://www.netflix.com/title/81321999
It has some striking pictures of two farm fields side by side.
One supports diverse plant life and produces nutrient-rich food. The plant roots prevent erosion, and retain water. The soil is rich and black. It's "regenerative".
The other has brown, dry, dead soil. It's tilled and irrigated and sprayed with chemicals. It grows a single crop, a monoculture.
Multiply that by a hundred years and thousands of consolidating mega farms all over the world, and you have a huge amount of erosion
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This problem has been well understood for decades (and by other civilizations for centuries), but is repressed / conveniently ignored by a wealthy, government-subsidized food industry
Here's a 2012 documentary about a 1994 project in China to restore degraded / desertified land, and it shows how poor entire states become when the soil is poor (which I suppose is not unlike the American midwest!)
https://www.youtube.com/watch?v=bjLV_aVRUmQ
https://rethink.earth/turning-desert-to-fertile-farmland-on-...
Chinese land has supported agriculture way longer than American land, and they have way more people, so they have these problems sooner
The US is going to get there