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Soil Erosion: Why soil is disappearing from farms (bbc.com)
189 points by joeyespo 3 months ago | hide | past | web | favorite | 133 comments

Even if wind and water erosion were eliminated, modern agriculture is fundamentally a form of mining.

Farmers grow crops that remove nitrogen, phosphorous, potassium and a variety of other minerals from the soil. The crops are shipped to cities typically located on rivers or oceans. The crops are processed, eaten and the nitrogen, phosphorous, potassium and other minerals are flushed into the rivers and oceans.

The elements can be replaced as long as supplies of natural gas to fix atmospheric nitrogen and reserves of potash and phosphate rock last. But it is ultimately unsustainable.

Plants need at least 42 minerals and soil in every location of the planet has those minerals, mostly in insoluable (non plant available) form. Aerobic bacteries and funghi have enzymes that extract those minerals and they are mostly kept in their bodies. Amoebas and worms of all sizes eat bacteries and funghi which releases a large amount of minerals in water soluable form in their poop and coincidently the poop is nearby the roots of plants. Some plants are called "nitrogen fixers" since they have clumbs of bacteries on their roots that convert N2 into plant available forms of nitrogen. Plowed soil is fluffy after plowing and compacted after a few weeks since the plowed soil has no structure. What can we learn from these facts?

* do everything possible to keep the life in the soil alive: do not use pesticides, funghicides or herbicides since the toxins are not specific and kill all soil life.

* aerate the soil to have enough oxygen (O2) and nitrate (N2) in the soil. Use a broadfork, but only with compacted soil.

* do not plow since that breaks the networks of funghi and ultimately deteriorates the performance of plants.

Want to know more? See the video "Restoring Soil Biology, Increasing Yields and Reducing Costs" by Dr Elaine Ingham: https://www.youtube.com/watch?v=pk14Qyulc9E

> do everything possible to keep the life in the soil alive: do not use pesticides, funghicides or herbicides since the toxins are not specific and kill all soil life.

It should be noted that glyphosate has antimicrobial and fungicidal properties.

Also, plants can turn the bedrock into dirt, either directly, or through their mycorrhyzal and rhyzosphere bacteria. Trees are especially useful to extract nutrient from rocks.

That being said, I think that Merril has a point. we're accelerating the extraction process (by dumping our waste products in rivers, rather than peeing/pooping where plants grow), and I have no idea how long we'll get away with these practices.

Human effluvia is full of drugs, and thus unfit for agriculture anyways...

> Human effluvia is full of drugs, and thus unfit for agriculture anyways...

For direct application, yes. But it could feed a pipeline where, say, the 3 generation of those nutrients could be harvested and applied to food crops.

What sort of pipeline? Biological?

Yeah, basically using it to fertilize a crop to grow a "green manure" crop for a couple of rounds and then cycling back to food crops.

Sewage is heavily treated in most places these days - usually by a biological process. The suitably sterilized solid waste can indeed be used as fertilizer.

sewage treatment plants can't remove drug contaminants

I don't see any reasonable argument why they should not be able to remove at least sizeable parts of drug residues. There is metabolism in the human body and the is bacterial metabolism. Organic matter will be broken down at least partly.

Sand in fungally dominated soils show signs of biological erosion similar to you see under lichen. What we can take from this is that soils under perennial woody crops can mine their own minerals, probably until the sun runs out of hydrogen.

But annual crops mostly grow either in prairie or disturbed soil ecosystems. Bacterially dominated soils. So any way you slice it, we need a wider mix of perennial and woody crops. Over a long enough time horizon, all of your fertilizer resembles compost and that compost has to derive its minerals from fungal soils.

If anyone is interested in this topic, the phrase to search for is "soil food web".


I’m wondering, what’s your opinion on the approach shown in The Biggest Little Farm?

Left me very hopeful and wondering if it’s something that could scale.

Recently I learned how much we depend on phosphate mining to provide nutrients for farming, and I found it unsettling how uncommon phosphate deposits are. Here's an entertaining sub-4 minute watch on the topic of how a majority of phosphate deposits are located in Morocco -- https://youtu.be/O0BooiAxQyY.

I just looked up how much different countries produce, and had assumed most phosphates would be coming out of Morocco. My guess was incorrect. It appears that Morocco produces ~13% of the world supply, but has ~72% of deposits. For constrast, the USA produces ~12% annually with ~2% of world deposits, and China produces ~45% annually with ~5% of all deposits. If I were the leader of a country with lots o' people, I'd be cozing up to Morocco a whole bunch. [1]

Knowing nothing about mining anything darn thing, I now wonder how interesting the work is in finding & mining new sources sources of phosphates.

[1] https://en.wikipedia.org/wiki/Phosphate#Occurrence_and_minin...

The Earth's crust contains 0.1% phosphorus by mass. It’s not going to run out, at worst it’s going to cost more to extract. Granted paying more than $425/ton might have an impact on food prices, but it’s currently a very low fraction of food prices. About 20% of overall fertilizer costs.

https://en.m.wikipedia.org/wiki/Phosphorus, https://farmdocdaily.illinois.edu/2017/07/fertilizer-costs-i...

It's a bit worrying that they talk about burning human shit to get phosphate when you can just compost it.

The issue is probably all the contaminants in human poo, especially medical: anti-bacterials, hormones, radioactive tracers. Maybe it isn't so much purifying the phosphate that matters, but removing components that would be bad to recirculate into our food chain.

High temperature composting deal with the most common problems anyways, and you preserve the nutrients rather than burn them up. The biggest problem is how bad water waste management systems are at producing fertiziler, the wide spread idea that it's ok to pollute our waste water with what ever, making it unusable for composte is not healthy. I do not think burning it can solve more than a tiny part of that problem.

I guess it's because composting doesn't guarantee the destruction of pathogens.

Yeah human waste fertilizer sounds like a very good way to get outbreaks.

Milorganite is a fertilizer here in the midwest which is kiln dried microbrobes from milwaukee water treatment system,


On the other hand phospor deficiency is easy to come by with smallish amounts of phosporous. Only at hard deficiency the yield will suffer strongly. The nutrient supply-yield curve is very steep in the lower end of supply and shallow in the range of optimal supply. Check Sonneveld et.al.

What I am trying to say is that we sure would like to give optimal supply to out plants, but slight undersupply will still give reasonable yields. Profitability issue? Yes! Problem with feeding the world? Rather not.

We will run out of phosphate soon enough. In the American mid west, the corn and hogs take turns to get the phosphorus cycle going.

When we run out of P, mining asteroids is always an option. How much of a viable realistic option...I don’t know.

I think there are two other viable solutions:

1. Synthesize food in labs using fermentation techniques to feed the world population.

2. Genetically modify Homo sapiens to synthesis food and tinker with metabolism.

Both the above seem more practical and likely feasible than destroying the planet with Ag for marginal benefits.

Phosphorus comprises about 0.1% by mass of the average rock you find walking around, the only thing that’s running out is the extremely high concentrations you find in specific areas.

What we are mining is essentially areas of ocean floor lifted up to the surface. We could also either mine other areas still on the ocean floor that also have high concentrations, or almost anywhere else at lower though still significant concentrations.

I am sure they are due for a regime change for oppressing their people at some point in the future.

Over 95% of a plant is just hydrogen, oxygen, and carbon that it pulled from the air or water. Only a very small percentage of the material in a plant is actually from the soil, so most of the activity on a farm is not fundamentally a form of mining.

> Only a very small percentage of the material in a plant is actually from the soil, so most of the activity on a farm is not fundamentally a form of mining.

This is demonstratably false, you only have to look at Hydroponics to see that. A lot of plants are difficult to grow via Hydroponics, and Hydroponicists go to a lot of trouble to put nutrients in the water that they use, despite the fact that _not_ doing so would allow the Hydroponics system to be more efficient and need less maintenance (the latter of which is the main barrier to general-use Hydroponics). If one looks at spray-based systems, the main cost there is the nutrients clogging the spray heads. However, without those nutrients, the plant will literally not grow.

The microorganisms, metals, and NPK in the soil are hugely important to the growth and nutrition of the resulting product.

That's not what he is saying, he is saying that most of the biomass is from hydrogen, oxygen and carbon, which it is.

Which is true but not too relevant, as he explains the limiting factor is not that the biomass is mostly hydrogen/oxygen/carbon, it is the lack of nutrients.

And as cited elsewhere, see Liebig's law of the minimum.

Liebig's law of the minimum

Liebig law of the minimum, often simply called Liebig's law or the law of the minimum, is a principle developed in agricultural science by Carl Sprengel (1828) and later popularized by Justus von Liebig. It states that growth is dictated not by total resources available, but by the scarcest resource (limiting factor). The law has also been applied to biological populations and ecosystem models for factors such as sunlight or mineral nutrients.


I disagree. Farming is surface mining.

Maybe aquaponics and hydroponics are only reliant on water and nutrients. And we should probably switch to soilless farming more..but soil based farming is most certainly surface mining and the most destructive thing we can do to this planet.

No. That’s an incredibly ignorant statement that is unfortunately commonly believed by many people these days.

We currently subsidize a type of agriculture that is very extractive. But farming isn’t inherently that way, and has only been that way for a few decades. I’ve seen the right way — working on a midsize farm that was producing a variety of crops and dairy from the late 1600s until around 2006.

Techniques like crop diversification, rotation, low-tillage, etc it is very feasible to create a sustainable agricultural environment. Think about the tragedy of all of the incredibly fertile and water-rich land that fed NYC in New Jersey that is now subdivisions. Now “environmentally concerned” people are drinking half gallons of crushed almonds, sugar and water grown in arid areas with threatened water supplies.

It does mean that you need to roll back the direct and indirect subsidy that creates exploitive markets. That means you don’t grow lettuce in the California desert. It also means seasonal vegetables and smaller scale farms.


world population in 1600 = 500 million current world population = 7.5ish billion expected population 2050 = 10 billion

subsidies wont make a huge dent. population reduction might. ..but that would take 150-200 years if everyone stopped procreating after half a surviving child.

None of this has anything to do with population. It’s all about money and short term gain.

If you’ve ever been to UMass Amherst, it’s in in the middle of the Pioneer Valley of Massachusetts, a fertile and lovely area of the country.

There’s a series of strip malls there that were mostly farms not long ago. What is now a Home Depot was a hothouse that grew flowers all year long.

That land fell in value because the US government invested billions to turn California into a farmers market for the world. That land is an asphalt parking lot because tax policy makes it easy for big box stores to be built for little or no investment. For example, Dollar General stores get thrown up for about $300k and the company invests something like $30k, that’s it.

That’s why you can be in a place like Georgia or South Carolina in the harvest season and walk out the door with peaches from 3,000 miles away.

I have lived in all three regions.

The US government doesn’t control California weather where we are clear to grow under full sun for 8 months in a year.

You are also wrong about Southern peach production vs California peach production. California produces the best and most of the peaches in the USA for fresh eating, varieties and also for canning. California produces five times more peaches than Georgia and South Carolina. NJ produces more peaches than the southern states. In CA, we do Ag well and have the best climate and soil. We are the number 1 Ag state in the USA with Ag income topping $45 billion. Why? Because we do Ag well...it’s unfair to strip away well earned meritocracy. You are wrong. You have no idea what you are talking about. Links below. I can’t get into a pissing match so you can bash CA Ag.

Amherst : https://weatherspark.com/y/25574/Average-Weather-in-Amherst-...

[..]Average Weather in Amherst Massachusetts, United States In Amherst, the summers are warm and wet, the winters are freezing, and it is partly cloudy year round. Over the course of the year, the temperature typically varies from 17°F to 83°F and is rarely below 1°F or above 91°F.

The warm season lasts for 3.6 months, from May 28 to September 17, with an average daily high temperature above 73°F. The hottest day of the year is July 21, with an average high of 83°F and low of 63°F.

The cold season lasts for 3.3 months, from December 2 to March 12, with an average daily high temperature below 43°F. The coldest day of the year is January 30, with an average low of 17°F and high of 34°F. [..]

Fresno, CA: https://weatherspark.com/y/1482/Average-Weather-in-Fresno-Ca...

[..]In Fresno, the summers are sweltering, arid, and clear and the winters are cold, wet, and partly cloudy. Over the course of the year, the temperature typically varies from 39°F to 99°F and is rarely below 31°F or above 106°F.

The hot season lasts for 3.5 months, from June 6 to September 21, with an average daily high temperature above 90°F. The hottest day of the year is July 29, with an average high of 99°F and low of 68°F.

The cool season lasts for 3.1 months, from November 20 to February 22, with an average daily high temperature below 64°F. The coldest day of the year is December 30, with an average low of 39°F and high of 55°F.


Also: South Carolina is more of a blueberry state than Peaches. Warm winters are compromising peach crop in Carolina and Georgia.


[..]California clingstone peaches are available from July 10 to mid-September, while California freestone peaches are harvested from April 20 to October 10. The Southern states of Georgia and South Carolina provide peaches from May to August. For all other states the marketing season is from July to September.[..]

[..]As of 2017, peaches are commercially produced in 20 states. The top four states in peach production are California, South Carolina, Georgia and New Jersey.

In 2017, California supplied nearly 56 percent of the United States fresh peach crop and more than 96 percent of processed peaches (NASS, 2018).

United States total peach production in 2017 was 690,100 tons valued at $599 million. California led the nation in peach production, with 541,000 tons valued at $376.5 million. New Jersey followed, producing 28,200 tons valued at $44 million. Pennsylvania produced 21,400 tons valued at $25.3 million, and Washington produced 12,770 tons valued at $12.3 million (NASS, 2018).[..]

Hm yea, so where does the water for the desert of CA come from? Isn't that what is being subsidized by USG?

I have often been amused by some of the delusions here on HN about food and farming. This one takes the cake.

Peaches grow on trees. Fruit orchards are not corn fields or thousands of acres of soy. They are perennial tree crops. We also sequester carbon much better than most other Ag states. We have a 8 month growing cycle without a drop of rain(that’s why almost all of processing tomatoes in the USA comes from California) while in the east, south and mid west, it’s not just the short growing season, but there is rain everyday in some parts that some don’t even irrigate.

If anyone thinks Georgia or South Carolina peaches are better than California ones..all I can say is ..Bless their hearts.

The USG doesn’t ‘subsidize’ water in California. California voters subsidize the cheap food the rest consume. California farmers have grandfathered water rights and we vote on it.

CA has contributed more to the GDP in Ag revenue and exports than ANY other state with $45 billion. Iowa lags behind at $22 million. Most of the Ag activities involving commodity crops..you know..those traded on the exchange..enjoy federal subsidies.

We grow fruits, nuts, vineyard crops and alfafa along with lettuce, strawberries and feed most of this country.

One of the federal subsidies doled out to mid west farms that grow gmo soy and corn (only 7% of which is for human consumption) is for Prevent Plant. Those farmers get subsidies if they don’t farm. (Channeling Major Major’s curmudgeon father from Catch-22.)

We do Ag brilliantly. We give much much more than we take. So much more. Our farms fed people during a long drought when we should be flushing our toilets. California voters paid dearly for water so the farmers can irrigate the fields.

But our farmers. Our votes. Our tiffs. It’s a family matter. As far as the rest of the country goes, a simple thanks would do.


Perhaps this kind of ignorance about what we do and the problems we face is why innovation and tech doesn’t serve CA farmers who grow the food we eat but millions are going into automating farms that grow crops receiving federal subsidies and commodities that are traded on the financial exchange. We are desperate for tech. We are on very thin margins. We get no help. We are not poor little rich princes.

I'm an ag engineer working on soil amendment for increased moisture retention, what kind of tech do you want?

Autonomous universal tool carrying platform to support minimal tillage protocols(7-10 functions..mechanical as well as monitoring and data collection) for sub 100 acre fields including perennials, orchards and annuals. A diverse farm has more than a few rotations per year. The platform cannot primarily be for data collection although that would be good too. The emphasis on data collection means huge data sets and clustering is mandatory and that would mean average field size should be several 100s or even 1000s of contiguous acres.

We are dependent on rain and the whims is climate every year..this year ..there was a 4-6 week late start and most nightshades are running late. And that means we had to quickly figure out and prepare for a diff pest and weed schedule than last year. So in built predictive systems is also useful. There are so many things we can do..but for now, I will take anything that will take reduce of mechanical and manual labour costs by automating field prep, transplant, cultivation and some of the harvest. Automation for large fields will fail. Too risky and costly. Small autonomous units swarming reduces risk and create multiple small data sets. This would also help small acreage farmers grow unique crops by giving them the attention they deserve. Mechanization is tyranny by conformity. Automation will help us experiment and create new germ lines and hybrids..I hope.

I speak for small acreage farms above.(that’s me)

California Ag needs harvest automation in the field. Field cultivation automation is already being developed. For larger farms, automation for harvesting soft fruits is tricky.

Orchard crops are a whole different matter. Personally..while there are many things to innovate, I think the issue of fire blight and replant pathogens are an issue. With perennials, data plays a far more important role because predictive systems will benefit permanent crops because they last longer and we get only one chance every year and being able to see what happened 6-7 years ago and what might happen 10 years from now is helpful for trees that have 30-40 lifespan.

And then there are things to disrupt with the supply chain and block chain etc. preventing wastage, traceability etc..and that’s being done but they are doing single crop as sectors at a time. But it doesn’t give farmers an edge as they are at the bottom most rung of the supply chain and value goes up at the top most rung of the supply chain ladder. For every penny we pay for traceability, the retailer profits rather than the grower. I don’t know how farmers can capture the cumulative value up the supply chain. They are just paying more for technology as they have new mandatory hoops to jump through now(traceability, block chain, certifications etc)

But I think I have digressed from what tech farmers need to what we’d like to rant about...

Permaculture is not, it's actually enriching the soil (in terms of living organisms) and the local ecosystem, it's a sustainable farming method gaining popularity with the decreasing productivity of common intensives monocultures

I agree. But yield is much less. Especially considering land mass for Ag is shrinking and we will likely face an uncertain future because of climate change. Indoor Ag can be controlled. I use permaculture and biodynamic methods for orchards and perennials but annual row crops, tillage methods seem to be the best option so far. I am a fan of permaculture but I don’t know if it’s feasible everywhere and for all kinds of crops.

Certainly prevalent forms of argiculture are akin to surface mining. My property is surrounded on three sides by a rotated field (corn, wheat, soy etc) and there's a 12-18" drop along those edges of my property line, persumably as the soil was extracted in plant form.

However I believe there are forms of soil agriculture that aren't surface mining such as a short rotation coppice. The primary molecular structures being extracted are lignin and cellulose, which are comprised of carbon, hydrogen and oxygen (that is, water and air sources).

>there's a 12-18" drop along those edges of my property line, persumably as the soil was extracted in plant form.

This presumption is incorrect. Do the math: 99+% of that mass loss is because of wind and water erosion, not plant growth.

Would his property not also experience the same erosion? I could see irrigation from the farming causing extra water erosion but wouldn't that ultimately be the same as when mining operations remove whatever minerals they consider waste?

The acceleration of erosion on farms is mainly caused by tillage (plowing), the building of fast farm drainage networks (vs infiltrating water to recharge aquifers), lack of trees to block surface-level winds (vs winrows), and heavy biocide application which kills the plant roots/fungal hyphae/bacterial aggregates that hold soil together.

>wouldn't that ultimately be the same as when mining operations remove whatever minerals they consider waste?

No because soil isn't waste, it's a valuable material.

No, because presumably his property has permanent plants with roots that retain the soil, while his neighbors are constantly tilling the land making it easily blown or washed away.

I don't see how this isn't analogous to mining still.

Coal mines clear cut mountains. A smaller portion of the mountain in the form of coal is kept and shipped. The other materials of the mountain are blown away as a side affect of the clear cutting operation.

Farmers harvest crops from their land. A smaller portion of the land in the form of crops is kept and shipped. The other materials of the land are blown away as a side affect of the farming operation.

Why are these functionality different other than one operation wants a mineral in the ground and one operation wants freshly harvested plants?

It’s surface mining of topsoil. Topsoil takes years and years to form and once it’s gone, it’s gone forever. Soil has structure and it’s alive. Soil biome holds not just water but also air and nutrients and bacteria and mycelium and has its own eco system.

Someone told me that you can indeed create soil by composting..well..that’s still compost. Not soil. Compost spread and left undisturbed by tilling will help soil regenerate. Instead ..we create fluffy soil by tilling and then we add amendments( and chemicals and toxic weed killers)..all life in the soil is ripped and tilled and eroded away as the structure of soil is gone...it is death..instead of acting as a carbon sink, we have changed soil by growing food and releasing more carbon into the atmosphere. Tillage farming is the most destructive thing we have ever done to this planet. And then it became fossil fuel dependent. The food we eat to live is what’s going to kill us. Farming... It’s literally going to kill us. It’s an open air factory... surface mining operation..it’s not ‘natural’. We are better off moving 50% of annuals grown for food to indoor farming like hydroponics and aquaponics... And stick to growing grains and perennials and trees and nuts etc outdoors which can be bought back into the fold of regenerative Ag. Tomatoes? Better indoors. Strawberries? Better indoors. Lettuce? Oh good grief! Certainly better indoors. So much to do.especially as tech breakthroughs..first amongst them is energy. New forms of capturing energy to mKe indoor farming sustainable. Nutrient management and disposal. Maybe more organic ways to formulate indoor Ag nutrients. Etc etc. but mostly not being reliant on dirty electricity and on the power grid for indoor energy needs. That bothers me the most.

You don't actually have to till, you just make slightly more money in the short term by doing that.

I agree. But industrial fossil fuel based global Ag is brutal on the soil..top soil once gone will take years and years to form..if at all it does ..

I wonder how much of that is your land gaining dirt, building up from the wind erosion around you.


> A major environmental concern known as topsoil erosion occurs when the topsoil layer is blown or washed away. Without topsoil, little plant life is possible. The estimated annual costs of public and environmental health losses related to soil erosion exceed $45 billion. Conventional agriculture encourages the depletion of topsoil because the soil must be plowed and replanted each year. Sustainable techniques attempt to slow erosion through the use of cover crops in order to build organic matter in the soil. The United States alone loses almost 3 tons of topsoil per acre per year.[10] This is of great ecological concern as one inch of topsoil can take between 500 and 1,000 years to form naturally.

> Based on 2014 trends, the world has about 60 years of topsoil left.

So yeah go ahead feed the overpopulation of the hungry, hopefully in 60 years there is tech to replace all the plants that can no longer be grown. In 60 years this is going to be another global warming situation that we have known about but yet let continue until we could no longer do so.

>hopefully in 60 years there is tech to replace all the plants that can no longer be grown.

And if it turns out the cheapest and best "tech" is soil conservation, what then?

"Tech" tends to mean high-tech, but high-tech is also high cost (see vertical farming). It's quite possible that low tech / appropriate tech solutions will win in the end.

Also, how many decades of R&D delay for this (rather... ambitious) Replace All The Plants Project are you asking for? The whole 60 years? Or should we tap the brakes (ie implement known soil conservation techniques) before going off the cliff?

> Based on 2014 trends, the world has about 60 years of topsoil left.

Playing devil's advocate, there's no guarantee that these trends will continue. For a related example of this go and look up the Malthusian catastrophe

I am going to live forever, so far I am doing fine... See most life extinct on planet... like 99%.

> tech

Several of the farms around where I live still use 40+ year-old farming equipment. Most likely, any new tech won't be deployed fast enough to make a difference, at least not on a global scale.

Crop rotation was a huge advancement in agriculture. It assists in soil nutrient replenishment. Additional minerals and synthetic nitrogen can be added if needed.

Both nitrogen and potassium are available in unlimited supply (and hydrogen from non-fossil sources can be used instead of hydrogen from natural gas). It's the phosphate, and possibly N2O emission, that constrain things. Eventually phosphate may have to be mined from average crust rocks, where it occurs at about 1000 ppm.

We can also be good citizens of the Earth and recycle the phosphorus we extract.

You can fix nitrogen with an electric arc. Using natural gas is way cheaper of course. But cheap enough electricity means you can have nitrogen fertilizer (and nuclear for example, fraught as it might be, is cheap enough).

Most of California agriculture is engaged in extracting fossil fertility that came from the ocean. Salmon runs -> bear poop -> soil for thousands of years. We killed all the bears and all the fish so this cycle is now unidirectional.

The UK has an extensive potash mine. Quite an amazing site - it extends out under the North Sea in places and has a laboratory doing various interesting science: https://en.wikipedia.org/wiki/Boulby_Mine

But what struck me about it was the seemingly pretty scary thought that we are apparently dependent on non-renewable sources like this to stay alive, and everyone continues life like it's a sensible way to proceed. What happens if/when supplies are interrupted? Or the mineral is mined out?

What does it take to change the way things are done? It feels like no tech startup is going to solve this in 5 years - more like a cultural shift that can take generations

> [...] eaten and the nitrogen, phosphorous, potassium and other minerals are flushed into the rivers and oceans.

What if we didn't though? Sewage could be turned into fertilizer, though probably not safely for growing food crops no matter how we treat it. Still, there must be some other way of putting the nutrients back in the local environment.

Off Topic: I argued a similar point a while back (albeit I think I mixed up phosphorous and nitrogen) on Hacker News and got downvoted: https://news.ycombinator.com/item?id=20139102

It's interesting how fickle hacker news can be.

Yes for that we need to limit chemical usage and try to focus on organic farming. Only them we can restore all the necessary elements in soil again.

As a former agronomist there are a couple of things in this article that concern me. It reads like a scare piece. Farmers for over fifty years have recognized the problem of soil erosion and are moving to reduce tillage.

Sadly no-till where farmers plant into last years crop is only mentioned once. No-till requires more management and adoption started slowly. But now better chemicals for weed control, better planting equipment and adoption of a best practices list has contributed to its successful adoption and it's popularity has exploded.

I am skeptical of the discussion of soil microbes which previously have been looked at as snake oil cures promising much but delivering little. There may be a genuine breakthrough this time, but show this skeptic the university replicated and peer reviewed research first. Far too often with these products all you see are farmer testimonials which unaccompanied by university research are a flashing red light indicating a scam.

Here is a recent overview from Washington State University "Soil biology and soil organic matter; What do recent discoveries mean for soil management?"[1] I copy one quarter of its provided references below here, just to illustrate the situation that there is really no paucity of peer reviewed work from this field.

About the potential for reversing the long term trend in soil degradation through microbially 'un-interested' and herbicide assisted no-till methods - wouldn't be appropriate to provide university replicated peer reviewed research which substantiates they have the situation covered ?

[1] http://csanr.wsu.edu/soil-biology-and-soil-organic-matter/

1/4 References:

Jackson, R.B., K. Lajtha, S.E. Crow, G. Hugelius, M.G. Kramer, et al. 2017. The Ecology of Soil Carbon: Pools, Vulnerabilities, and Biotic and Abiotic Controls. Annu. Rev. Ecol. Evol. Syst. 48(1): 419–445. doi: 10.1146/annurev-ecolsys-112414-054234.

Janzen, H.H. 2006. The soil carbon dilemma: Shall we hoard it or use it? Soil Biology and Biochemistry 38(3): 419–424. doi: 10.1016/j.soilbio.2005.10.008.

Kallenbach, C.M., S.D. Frey, and A.S. Grandy. 2016. Direct evidence for microbial-derived soil organic matter formation and its ecophysiological controls. Nature Communications 7: 13630. doi: 10.1038/ncomms13630.

Kästner, M., and A. Miltner. 2018. SOM and Microbes—What Is Left From Microbial Life. In: Garcia, C., Nannipieri, P., and Hernandez, T., editors, The Future of Soil Carbon. Academic Press. p. 125–163

Woolf, D., and J. Lehmann. 2019. Microbial models with minimal mineral protection can explain long-term soil organic carbon persistence. Scientific Reports 9(1): 6522. doi: 10.1038/s41598-019-43026-8.

Thanks for posting this research. It does a nice job of explaining stuff that has been observed for a long time but which there was no explanation. Another reason why it's worth my time to be involved with the HN community!

Me too, thanks for regarding. On second look, it's a better article than I deserved to hit on - just quickly plucked from WSU since i've been impressed there before :)

It's not a scare piece, the rate of topsoil erosion is truly alarming. As you say, many farmers recognise the problem and are attempting to address it, but many others are not. There is an economic problem here, how do we encourage farmers to adopt best practises in the race-to-the-bottom food economy?

Soil erosion is a reversible process but it will require a little effort and planning. When it works it's an investment that actually pays off.

Here's a nice example of the Chinese restoring some soil: https://rethink.earth/turning-desert-to-fertile-farmland-on-...

I've seen a documentary with some before and after video footage. Quite amazing difference: https://www.youtube.com/watch?v=IDgDWbQtlKI

Planned grazing is another approach that has seen some success: https://www.theguardian.com/sustainable-business/2014/aug/19...

Is soil erosion ever naturally reversed ?

It seems to me to be a one way downhill process ?

It sure does, see Rangitoto Island for an example (https://en.wikipedia.org/wiki/Rangitoto_Island).

A bare volcanic rock after its eruption 600 years ago, the island is now largely reforested. Lava fields contain no soil of the typical kind, so it must come from windblown matter and slow breaking-down processes of the native flora.

Sure, soil building happens naturally.


Natural rates of formation are ~1 in/century (2.5 sanetimeter units).

Obviously there was no soil at first since it's dead organic matter.

Yes, but that’s not “reversing” so much as completely rebuilding soil, which takes decades of no farming and no tillage.

A lot of loss can also be trivially reduces by planting rows of trees between fields, which I saw all over the place in NZ, but haven’t seen elsewhere.

Pretty standard in Europe : https://en.wikipedia.org/wiki/Bocage

Erosion is why there is soil in the first place. Moss and lichens for one create it from rocks.

> https://www.truthordrought.com/holistic-grazing-myths

Based on quickly skimming that webpage, its main scientific source is one article in 2014 in International Journal of Biodiversity. This International Journal of Biodiversity [1] was only published from 2013 to 2018. It is such a small and fringe journal that I can not even find an impact factor for it. Also its publisher [2] has occasionally been accused of predatory practices. Without reading the article, I cannot of course directly comment on the quality of the study. But publishing in such a small-time, fringe journal gives a bad secondary signal.

[1] https://www.hindawi.com/journals/ijbd/contents/

[2] https://en.wikipedia.org/wiki/Hindawi_Publishing_Corporation

Read the guardian article, it cites a few reputable sources to debunk the debunkers. So, I'd be careful calling bullshit on things based on some blogs with an agenda. Skeptical science seems to exist to empower climate change deniers with the illusion of factual reality. Bullshit in other words.

Ultimately, it seems there are a few projects out there practicing instead of theorizing and converting actual desert back into fertile land.

> Skeptical science seems to exist to empower climate change deniers with the illusion of factual reality

It seems like Skeptical Science is "Getting skeptical about global warming skepticism". They are a pro global warming site.

That’s possibly true, but a position paper from a group whose stated goal is to promote the vegan diet should be regarded with some skepticism when it comes to presenting unbiased scientific facts.

Wasn't holistic management invented by Allan Savory? (the guy that killed 40,000 elephants)

Yep; something he readily admits to in his ted talk as something he royally messed up. That doesn't mean everything he says or does is bullshit. Basically all he is saying that cattle grazing and fertilizing land can be a good thing and if you do it in a somewhat data driven way by actually looking at how the land responds, you can get some impressive results.

We produce food for humans, pets, livestock.

Most of the livestock is not necessary, and 30% of all food will be wasted.

Paper is also responsible for topsoil loss. Much of the paper is used in advertising campaigns that receive little to no attention from consumers, or to communicate information that could be sent electronically. Some more is used in redundant forms of packaging.

We all have known how inefficient our processes are for a long time. But our expectation is that the environment should adapt to our needs and not the opposite. This belief is wrong, and will be proven wrong in the next decades.

I really enjoyed the book Third Plate by Dan Barber. (https://www.amazon.com/Third-Plate-Field-Notes-Future/dp/014...)

While I don't know if the methods explored in the book will be able to sustain the entire world population. I really liked how he argues in this century we can focus on growing food for flavor and not just quantity and flavorful foods generally come from farms that have bio dynamic practices which support soil health and eliminate the need for nitrogen based fertilizers.

One thing I'd love to see more studies about is adding charcoal to the soil. There is decent evidence that this greatly improves soil quality as the large surface area of the charcoal particles allows microbes to grow and stores water. It also has the added benefit of capturing carbon in a form that is stable for millennia.

Bio char. But it works in more tropical areas. Otherwise it has to be shipped. South America case studies plenty.

Hmm, afaik up to 10% biochar is considered beneficial in any soil and will keep nutrients fixated in the soil, more than that is mainly good since it removes co2 from the environment.

Why ship it? you just burn brush and waste where you have it and put the fire out before charcoal turns to ash and then innoculate it with compost and you are done..

New Delhi and other cities are suffering from farms burning off dry wheat stalks. Will a charcoal process offer an incentive to farmers to burn hay cleanly?

I'm curious, why it doesn't work in temperate climates? Also, I think it heavily depends on how "rich" / volcanic the soil is in the first place, perhaps?

https://iopscience.iop.org/article/10.1088/1748-9326/aa67bd : here

[..]Here we use a global-scale meta-analysis to show that biochar has, on average, no effect on crop yield in temperate latitudes, yet elicits a 25% average increase in yield in the tropics. In the tropics, biochar increased yield through liming and fertilization, consistent with the low soil pH, low fertility, and low fertilizer inputs typical of arable tropical soils. We also found that, in tropical soils, high-nutrient biochar inputs stimulated yield substantially more than low-nutrient biochar, further supporting the role of nutrient fertilization in the observed yield stimulation. In contrast, arable soils in temperate regions are moderate in pH, higher in fertility, and generally receive higher fertilizer inputs, leaving little room for additional benefits from biochar. Our findings demonstrate that the yield-stimulating effects of biochar are not universal, but may especially benefit agriculture in low-nutrient, acidic soils in the tropics. Biochar management in temperate zones should focus on potential non-yield benefits such as lime and fertilizer cost savings, greenhouse gas emissions control, and other ecosystem services.[..]

That appears to be a limited meta-analysis that itself postulated the reason temperate yield didn't improve because temperate soils were more fertilized on average than the tropical soil studies.

We're talking in the context of soil depletion in this thread, so I don't think their limited conclusion applies.

Possibly. I haven’t done any studies. I find good soil management with rotation and maintaining soil biome is sufficient in my Ca 8a/8b soil. My fields have soils that can be categorized as yolo loam and adobe can’t.

One thing not mentioned often about rainforrests is that their soil is actually pretty damn terrible. Which is also why you see things like carnivorous plants there.

So what if rainforest soil is terrible...their main function is to sequester carbon and act as a carbon sink supporting habitat and balance terrestrial ecology.

That is more for "why it helps there in the first place" than any disparagement of the rainforests. That the soil is terrible is more reason to leave them there - especially when they provide steady rain.

It isn't like temperate climates where you can rotate between farms, fields, and forrests over time easier.

right. i hear you.

may i ask what you mean by 'terrible'...nutritionally deficient or acidic..etc etc?

It's my understanding that charcoal, ie burnt wood, is basically inert and unusable by plant life.

I was at a soil management talk once, out in a paddock, and we dug a few holes looking at biomes and general soil quality. When we dug up bits of charcoal, the man said nothing has been burnt here for at least 50 years. It's my experience that wood is better at storing water: if interested have a look at hugelculture/ hugelkultur. It's a method that deliberately buries timber for nutrient and water retainment and as it composts it continues to feed the soil nearby.

OP is possibly posting the query in relation to what they've heard about Terra Preta, which is a dark and healthy soil found across the Amazon, rich in charcoal, and suspected to be significantly anthropogenic in origin...


- ed

I think charcoal's use in this context is more in terms of a structural matrix, rather than itself being of 'nutritious value'.

Charcoal is very useful for plants.

It is extremely absorbent to anything, specially nutrients in the soil so they don't get washed away by rain or irrigation. it releases them slowly.

I have done tests myself with very small quantities, 50 or so plants, half of those without, half with it, and plants certainly improve a lot.

We need scientific studies of thousands and thousands of plants for info about the combination of all those things.

It will require several disciplines, like genome extraction from soil, computer science to identify the microorganism present, lots of sensors for humidity, temperature, ph and so on.

Tillage is killing organisms living in the soil, which are crucial for fertility and resistance to erosion. Permacultures have interesting techniques, like covering the soil to let weeds die and enrich the soil at the same time, not sure how those techniques can scale, even if they are highly productive. There are also the use of livestocks: https://www.ted.com/talks/allan_savory_how_to_green_the_worl...

other links: https://en.wikipedia.org/wiki/Topsoil#Erosion http://www.fao.org/3/a0100e/a0100e07.htm http://www.fao.org/3/t0389e/t0389e02.htm

Agriculture is one of the biggest environmental catastrophes humans have perpetrated. Entire ecosystems have to be destroyed. I always find it disturbing when vegetarians think eating plants is a peaceful affair.

One could argue about organic agriculture in balance with the environment, unfortunately it produces on average 20% less than monoculture industrial agriculture[1] and the food demands of the planet are only growing.

[1] https://news.berkeley.edu/2014/12/09/organic-conventional-fa...

What comes to mind is something called "zero budget farming" invented by in India by Subhash Palekar. This is basically an approach based on the premise that modern farming including Organic farming is killing the microbes and other beneficial organisms in the soil critical to sustainable agriculture. http://www.palekarzerobudgetspiritualfarming.org/zbnf.aspx

One of the best books I’ve ever read on this subject is “Tree Crops”, Smith, 1929. Soil erosion is his main focus and he quotes FDR who says that a nation that destroys its soil destroys itself.

The subtitle of the book, A Permanent Agriculture, inspired Permaculture — a niche but growing group of farmers who look towards perennial crops with their deep root systems, and less fickle needs for inputs and maintenance. Because these plants are permanent, tilling is all but eliminated.

The green revolution with its world-changing chemicals born out of the world wars led to a boom in yields, and has fed the world for the past century. But with our changing climate, and the obvious destructiveness of industrial farming (runoff, land use change and deforestation, emissions from tilling, emissions from chemical production and transportation), it’s pretty clear we need a new model.

If you look at my post history, I recently linked to The Carbon Farming Solution — it’s fascinating and phenomenally well sourced. There’s an active push to develop perennials to replace many of our staple crops. This is, er, fertile ground for research.

Guess it's time to check in with the hydroponics scene and see how things are coming along.

Farmers in Austria (where glyphosate was recently banned) are worried that without glyphosate erosion will accelerate due to the lack of reasonable chemical alternatives. This will be interesting to see unfold.

No/minimal till regenerative Ag would work.

We have to change design of farm Mach aka tractors. Good opportunity for automation in Ag to step up to the plate and create a new paradigm shift

Glyphosate is no till farming already and keeps the soil in place with the dead weed while it decays.

Farmers aren't paying money to spray it for shits and giggles.

Although it would be interesting to see both a robotic mechanical weed killer's operation, performance, and economics in comparison.

Ok. Minimal or No till/non chemical farming then.

There is no need for chemical Ag if we have automation. Chemistry removed the need for hard labour. It is still possible to use mechanization to replace toxic chemicals because weeding is all about timing, but even with mechanization, labour costs add up. Automation is the solution. And we have the capability and tech to do it now.

I suspect that there will be some resistance and possibly nascent tech will be bought out to die in a dark vault after being acquired by the big players whose market share will be threatened. But it’s only a matter of time when the transition from tractor to Ag bots happens seamlessly..I feel the big tractor companies are just trying to time and manage the transition. They certain have a massive market share. Chemical Ag is certainly out. Automation will be the new paradigm.

Isn't there something extremely wrong about the math in this blerg? Surely 12 million hectares produces a lot more than 20 tonnes of grain annually. Did they mean 20 tonnes per hectare? Otherwise it's low by a factor of ten million. Either way doesn't make sense.



A hectare is ~2 ac.

Wheat looks like 2-5 tonnes/hectare

Looks like 20 tons per hectare is pretty high, but

It's 20 million tonnes per year according to the source https://www.unccd.int/actions/united-nations-decade-deserts-...

Dirt-based farms are antiquated and inefficiently use resources compared to fogbox and airponics. Healthy soil is great, if it's for grassland vegetation browsed by managed mega-herds.. otherwise, the trend (climate change and lack of roaming mega-herds) is towards desertification.

I presume they will, but will modern greenhousing and 3D farming (under artificial light in factories) help to reduce soil erosion, or not?

Scale is the problem.

Just constraining yourself to the US and using the arbitrary 2000 calories per day per person, the US needs to produce about 2.4 x 10^14 food calories per year. I'll leave it as an exercise to the reader to figure out how many greenhouses that is or how many 3d hydroponic farms, but the counter offer is a few thousand square miles of corn.

Sounds like a good use case for GMO.


I never make this kind of comment, but that was unreadable. It broke scroll speed, didn't have a reader view, and the text constantly shifted from left to right hand side of the screen.

This was literally unreadable for me on Firefox. It insists on me rotating my phone (?), even though I'm viewing it on a desktop computer.

The entire article is blocked behind that "rotating device" icon. Really terrible job.

Looking at it on an iPad it insisted I go from landscape to portrait, a tad impertinent.

Same for my Surface clone, I had to detach the keyboard and rotate to portrait. I ended up reading it in firefox reader view.

It did that on my Linux laptop running Firefox, despite the fact that I can't actually even do that.

Also hard to read the text as it scrolled over a busy background. I gave up.

Agree. Thank goodness for reader mode.

With regard to fixing this, the article contains a link to:


"To restore our soils, feed the microbes" (2017)

Agriculture is pretty much the dumbest thing you can do to land (other than simply poisoning it.) It's a process of converting ecosystems into people (and, since the invention of artificial nitrogen fertilizer, converting oil into people.)

Ecosystems are more productive, so if we imitate Nature with "applied ecology" (such as Permaculture), we can actually create a new kind of civilization. One that generates more healthy soil than it loses.

Toby Hemenway (RIP) gave a talk, "Redesigning Civilization -- with Permaculture"

> Modern agriculture, industry and finance all extract more than they give back, and the Earth is starting to show the strain. How did we get in this mess and what can we do to help our culture get back on track? The ecological design approach known as permaculture offers powerful tools for the design of regenerative, fair ways to provide food, energy, livelihood, and other needs while letting humans share the planet with the rest of nature. This presentation will give you insight into why our culture has become fundamentally unsustainable, and offers ecologically based solutions that can help create a just and sustainable society. This is the sequel to Toby's popular talk, "How Permaculture Can Save Humanity and The Planet, but not Civilization."


That is nakedly not true at all for yields and shows a massive ignorance of history, trophic layers, ecology, and economics to declare it less productive. Less biodiversity by definition but that is essentially the whole point of agriculture - producing what you want.

Permaculture really seems to be the new Lysenkoism. They keep on making grand claims about their sustainability and output and how it is the only sustainable way yet their yields aren't even any better than conventional farming with crop rotation.

If you want to preserve nature your best bet is unsexy density - scales better than local and distributed. Even solar and wind which benefit from being spread around are still clustered.

You haven't had time to watch the video?

> Permaculture really seems to be the new Lysenkoism.

No need for insults.

> That is nakedly not true at all for yields and shows a massive ignorance of history, trophic layers, ecology, and economics to declare it less productive.

Yeah, I actually know a lot about this and you are just plain wrong.

Agriculture has always been destructive. The masses of people have historically been miserable and malnourished, suffered from regular famines, etc.

Applied ecology generates greater yields per acre, and per unit of labor input, than any other system we have tried. It's a new form of civilization.

Yeah bro who needs food anyway

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