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Comment by Merrill | Hacker News Reader

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.

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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.

https://www.health.harvard.edu/newsletter_article/drugs-in-t...

some but not all

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.

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.

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

https://en.m.wikipedia.org/wiki/Soil_food_web

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...

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

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

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.

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.

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

https://www.milorganite.com/using-milorganite/what-is-milorg...

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...

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.

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.

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.

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.

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).

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 ..

>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?

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

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.

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

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.

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.

well..

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.

https://www.agmrc.org/commodities-products/fruits/peaches

[..]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.

https://en.m.wikipedia.org/wiki/Water_in_California

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...

https://en.wikipedia.org/wiki/Topsoil#Erosion

> 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.

> 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%.

>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?

> 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.

> 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.

https://en.wikipedia.org/wiki/Liebig's_law_of_the_minimum

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.

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