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Comment by BugsJustFindMe | Hacker News Reader

Forgive me if I missed the answer, but where is it going?

Soil erodes into waterways which spill into oceans.

Btw, the nutrients that the soil carries can cause spikes in algal populations, which then lower the oxygen content of water bodies, killing large numbers of other organisms like fish.

> spikes in algal populations, which then lower the oxygen content of water bodies

How can algae lower oxygen when oxygen is the very byproduct of their photosynthesis? They literally turn water into oxygen. Wouldn't that increase the oxygen content?

When the algae bloom dies oxygen is used during decay

https://www.epa.gov/nutrientpollution/effects-dead-zones-and...

This is similar to how mulch works to suppress weed growth. Mulch is decaying matter and nutrients like nitrogen are temporarily 'locked up' during the decay process.

The story just keeps giving, isn't it? Initial thought I had was, well maybe they'll drag out and filter (for salt) ocean floor sediment to use it.

During the Dust Bowl, a lot of the soil blew away into the Atlantic Ocean off New England. Not sure how they knew that but I’ve come across this a number of times. Absent organic matter, the soil becomes dust and literally blows away.

The wikipedia page mentions it - the prevailing winds are west-to-east across much of the US and Canada due to the jet stream. In the winter the jet stream also moves further south. It mentions some of what must have been epic multi-day dust storms that started in South Dakota and reached Chicago one day and the east coast the next. New England had red snowfall from the residual dust in the air.

I was surprised recently when I was watching an Iowa corn farmer on youtube who is the new generation taking over the farm and trying to change things for the better by doing "new" things such as no till farming. I remember reading about no-till as a kid back in the 80s and there are still people who are just now getting the memo and trying it. I loved farming but didn't take over the family farm because my dad was reticent to trying new things, and chose computer programming instead.

> I remember reading about no-till as a kid back in the 80s and there are still people who are just now getting the memo and trying it.

I remember as a kid in the 80s watching people try it. They either went bankrupt or soon pulled the old iron back out of the shed. But the march of technological progress continues. The tools on the market now aren't the same tools they had in the 80s. It stands to reason that it is going to be tried again.

Not no-till related, but I recently bought an implement for my farm and my grandfather was concerned because a similar tool he had decades ago didn't work well on the farm. But the new tool is only similar on the surface. When you start looking at the details it is very different, benefiting from decades of advancement. It's worth trying again.

What is the implement you bought?

Where I live in the US, no till farming is common and it is growing in use.

I sometimes wonder if places like Egypt used to be covered in much more fertile land and perhaps they overdid the agriculture for a couple 100 years which turned it into an arid wasteland (I'm a total geology noob.)

No, ancient Egyptian civilization was always been dependent on the Nile not just for water but for the flooding that brings eroded trace minerals and deposits them along the basin. That's why we have so much material on ancient Egyptian civilization: the desert is so arid and has been for Egypt's entire history that the normal processes that would break down papyrus or other organic matter were significantly slowed down as long as they were buried far enough away from the Nile.

10,000 years ago monsoons hit the sahara, but they stopped about 5000 years ago and it turned back to desert. There are carved stones of giraffes and such. The society with Pharaohs etc. emerged around the time the sahara dried.

https://www.historytoday.com/archive/history-matters/swimmin...

Sahara's Abrupt Desertification Started By Changes In Earth's Orbit, Accelerated By Atmospheric And Vegetation Feedbacks https://www.sciencedaily.com/releases/1999/07/990712080500.h...

Via the wikipedia article on the Sahara desert. I think many deserts come and go based on climate patterns

Fascinating article, thanks. The main author Martin Claussen has many papers on that and related subjects, available here:

https://mpimet.mpg.de/en/staff/martin-claussen/publications/...

Claussen on Google scholar: https://scholar.google.com/citations?user=udBYQ-cAAAAJ&hl=en

Ancient Egypt relied on the Nile flooding the land. Now with the dams the flopding has stopped but they are also having trouble with the soil.

A recent HN comment implied that camel herding was a significant factor in aridification of North Africa and the Middle East. The context and tone made me wonder if the comment simply reflected anti-nomad (i.e. anti-Bedouin, anti-Berber) prejudice, but there could just as well be something to it. I'm trying to avoid rabbit holes so I put it out of mind.

The comment seems incorrect. Herds are good for the soil. They flatten grasses keeping moisture in, allowing for more growth. In the past, people believed the opposite - and this is perhaps still believed in parts of the world.

Such flawed thoughts about desertification led them to kill off tens of thousands of elephants in Southern Africa, which sped the process up much faster. Allan Savory: https://www.fastcompany.com/2681518/this-man-shot-40000-elep...

https://www.sciencedirect.com/science/article/pii/S016788092...

Managed properly, yes. The soils of the Midwestern US were formed largely by herds of migratory bison for instance.

The problem comes in when you don't defer grazing or give things a chance to regrow (see video in sib comment below). That absolutely can lead to desertification.

As populations increase and nomadism becomes nonviable (so ground is not given a rest from grazing) it appears that's what happens.

> The comment seems incorrect. Herds are good for the soil. They flatten grasses keeping moisture in, allowing for more growth. In the past, people believed the opposite - and this is perhaps still believed in parts of the world.

For some reason, the idea of complex organisms (in this case: mammals) migrating to new lands and fertilizing it seems counter-intuitive to me, but it does make sense in some way. I would've assumed that more simple organisms took this land long before mammals emerged.

The biggest gripe I'd have with it would be: why would they move into those lands? There's nothing there for them. But the idea of them slowly extending fertilized soil does seem intriguing.

It appears sort of counter-factual to me that we, who are (presumably) even more complex, seem to reverse this process. There seems to be a sweet-spot in evolution of a species to benefit the land on which they live on (and that around it), and we seem to be past it.

Goats are also a harbinger. They can and will eat any last remaining plant matter in an area, tipping it fully over to desert.

It’s often overstated as goats being destroyers. They aren’t or don’t have to be. The goats are the agent of destruction, but the herders are the actual destroyers.

For the restoration of the loess plateau in China, they mandated that goats had to be corralled instead of ranged, to allow the restoration to get a foothold instead of ending up as the most expensive goat meat ever.

This very well could have some truth.

This video popped up on youtube recommends a few weeks ago (Iran).

https://www.youtube.com/watch?v=ZJe8wWFh_w0

I've never seen ground that naked, not a spec of green except for trees. (and this coming from someone who lives in a very arid region of the SouthWestern US). Even very arid land (in Nevada or Arizona for instance) has significant vegetation so I wondered what was going on.

Part of the way through the video (6:09) it becomes apparent (to me anyway). Goats and sheep. Somewhere in there they are actually beating tree leaves down for the critters to eat because there is simply nothing else.

That's a fascinatingly stark landscape. I've visited rural communities in Mexico (semi-arid), Ecuador (highland grass lands), and SE Asia (jungle) that have that same remote village vibe, and the lifestyle similarity makes the contrast with the landscape all the more fascinating. I've also visited the Gobi desert (at least, the edge of the Gobi, where the mile-high sand dunes meet the endless grass lands) and that landscape in Iran somehow seems so much more desolate.

Judging by this 1977 UNESCO publication, "A Halt to Desert Advance", https://unesdoc.unesco.org/ark:/48223/pf0000046663, this recent IPCC report on desertification, https://www.ipcc.ch/srccl/chapter/chapter-3/, and the consistency between them, it would seem grazing is indeed considered a major factor, if not the major factor in many areas, for desertification[1].

[1] Maybe the author wasn't using the terminology correctly, or the terminology shifted or was refined subsequently, but in the article, "A precarious balance upset", from the 1977 publication the author suggests that desertification can at least in principle lead to aridification as stripping the land of vegetation dries out the soil, which can ultimately effect precipitation patterns. EDIT: Okay, I think I get it now. It's the reverse: aridification can lead to long-term desertification, while there other processes that can establish long-term desertification, notwithstanding the end result is also aridity.

A similar thing happened in south Texas - the land that Big Bend state park now occupies was grassland in the 1880s but because it featured low rainfall, was quickly overgrazed. The owners ended up giving the land to the state because it had been turned into worthless desert, coincidentally in 1935. Now 85 years later it still hasn't recovered to grassland but has beautiful desert vegetation. It is simultaneously beautiful and horrible.

I don't think it's the goats! I think it's the salinity found in parts of the Zagros mountains and this video was probably recorded in the Lake Urmia watershed. Pistachios are especially salt tolerant so they're the only plants that can grow there, despite the marine deposits.

Interesting read on Lake Urmia!

One thing that terrain is not though is part of the Lake Urmia watershed, as it's high mountains that have obviously been inhabited for a long time.

Make it a couple of 1000 years: https://en.wikipedia.org/wiki/Mesopotamia#Agriculture

>Over time the southernmost parts of Sumerian Mesopotamia suffered from increased salinity of the soils, leading to a slow urban decline and a centring of power in Akkad, further north.

Yes, the desert hasn’t always been desert, though the shifts aren’t attributed to human activity.

https://www.livescience.com/4180-sahara-desert-lush-populate...

As others have noted, water erosion is a major factor, but there are others.

The Dust Bowl in the US occurred after a drought coincided with recently-arrived dryland farming (unirrigated land) and overtilling. The topsoil from the Oklahoma and Texas panhandles was deposited across the U.S. at points east, as far as New York City.

Tilling itself can expose and degrade carbon in the topsoil, which is why various no-till farming methods are increasingly employed.

Wikipedia has a good overview:

<https://en.wikipedia.org/wiki/Soil_erosion#Physical_processe...>

Rivers carry it to the sea

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