Someone on here recommended this book by David R Montgomery, and after reading it, it should be required reading for everyone.  The first half, regarding societies and soil in history was a real eye opener, answered a lot of my long un-answered questions.  The last portion, dealing with farming today was obviously written while sitting behind a desk of his left coast university, based mostly on personal biases about ag input companies, capitalism and large scale farming.

Some comments:

He doesn't believe farming in South America is sustainable at all, and he has toured there.  The only places he thinks modern farming is somewhat sustainable is the Midwest US, most of Europe, and parts of China.  None of Africa, Australia, South or Central America.  Nothing tropical or subtropical.  That might be good news for midwest farmers, but not so great for mankind, maybe the $15000 per acre folks read this book first?

The cradle of civilization, which today is mostly barren desert, used to be forests then farmland for centuries.  Rome used to import(to be polite) grain from Egypt, and what is now Libya, Algeria etc.  Hard to imagine, considering Egypt is now the worlds largest wheat importer. 

I now understand why archeological digs are always digs, I couldn't figure out how soil accumulated fast enough to bury a city in a millenia or two.  Turns out farmers expanding from river valleys, where the cities started, into surrounding hills created enough erosion to eventually bury the cities under dirt.  ruining both the hills, and the river valleys below in the process.  He also describes a number of port cities which are now far inland thanks to erosion.

He devotes a large section to the Palouse, which posters here claim has no erosion.  Montgomery claims otherwise, the numbers are staggering, who is right?

I do agree with his assertion that tenant farmers or absentee large scale farmers, are unlikely to look after the land as well as owners and smaller scale farmers would, within reason.

Evidently, the solution to soil degradation, and losing all of the nutrients, is to NOT apply chemical fertilizer..............  I haven't quite figured out the math behind that yet.   Apparently manure has some magic ingredient in it that multiplies nutrients when livestock are grazing..........I am the worlds biggest fan of using manure, but last I checked, cows can't "fix" nutrients out of thin air, just recycle some of them.  I realize the book is a few years old now, but I don't think he realizes how much land is no-tilled, has cover crops, and how rarely a plow is used on this continent.  Looks like a lot of research and travel was done on the rest of the world, but not closer to home, but maybe that is just my own bias.

If the rates of erosion worldwide suggested are close to accurate, we are in a lot of trouble, and very soon.  I find it hard to believe, just looking out my backyard.  But I see pictures on here all the time with dust blowing, gullies and washouts.  Here, with snow and frost half the year, and bare ground for a few weeks at most, I've never seen erosion.  In recent years, the soil has rarely ever been dry enough to even make dust.  Runoff is crystal clear.  The only gully I've seen is where I started it with a drainage ditch in mellow black soil that was brand new, and the dirt settled into its own delta shortly after.  Of course, we mostly have clay and we are mostly flat, which may explain a lot.  So is erosion still happening here and it is just too slow to see in a human time frame?  The degradation of our soil however is painfully obvious, and the oldest is barely 100 years old now.  I've got kids who want to farm, and I take the sustainability of what we do very seriously.  It is too bad that doing the right thing usually requires time and money now, for a payback generations later.  

So do I have backyarditis, and erosion really is that serious?  What is happening in your area?  Who has travelled the world and seen what is happening
I know when we were in the Black Sea region of Russia, I saw huge washouts of beautiful black soil after big rains, and it is quite flat ground, with little or no no-till in that area.

One way I look at things, the soil is still out there somewhere, not lost forever, much of it is still sitting in deltas in the Mediterranean, Black Sea, Caspian Sea, , Gulf of Mexico,  Mouths of the Amazon etc.  But, by the time we realize we need to get it back to where it came from, we may be also facing a shortage of the energy required to complete such a massive task.

I really want to spend some time on google earth and see some of this myself, since I don't think I will be going to Iraq or Syria in the next few days to see where it all started.

I do highly recommend the book to all fellow farmers, and for that matter, everyone who eats, I do however believe the section about modern agriculture could use more research and a more balanced view, possibly a lot less about global warming and anti-business.