As every farmer knows: it's not the weight that matters but the soil compaction, and that's a function of weight over surface area of the contact patches of whatever drive train your tractor has. That's also why tractor tires are so wide, and high flotation tires are commonly used.
Another way in which farmers combat soil compaction is by aeration and tilling.
It's true though that tractors are getting larger and heavier, but farmers are pretty knowledgeable about these things and usually take them into account when deciding what kind of machinery (on what kind of tires) to use for their soil, after all, if they get it wrong they may end up negatively impacting the yield of their land.
Finally, crops tend to be planted in rows for convenient mechanical processing, and while walking behind a tractor you can actually see the soil rise again after the tractor has passed, usually because the soil acts as a sponge, the tractor squeezes the water out and once it has passed the soil will spring back. It's a bit strange to realize that the ground you walk on is so springy because you normally don't notice it.
The main take is "while surface contact stresses remained nearly constant over the course of modern mechanization, subsoil stresses have propagated into deeper soil layers and now exceed safe mechanical limits for soil ecological functioning".
i.e. they state that the stresses propagate deeper into the soil, regardless of the pressure imparted on the surface.
I dont understand it exactly, but thats what they are saying. I guess its something to do with the increased overall mass being supported by and compressing the underlying soil layers, rather than the (relatively) shallow sub-surface compaction we are usually concerned about.
Let's say you have a load of 1000 kg on a 1 square meter steel plate on a field. What is the compression 1 meter underground directly below? Less than at the surface. What about compression 1 meter underground and 0.5 meters to the side from the center, ie below the edge of the plate? Even less. And 1 meter to the side, even than that. The load spreads underground. From a small point load, it dilutes fast with depth.
What if you add a similar load directly adjacent to the previous one. Pressure is same but area is added. What is the compression 1 meter underground, at the border between the plates. It's more than in the previous case, since both loads now contribute to it.
So there is a sort of load pyramid that has to form underground to support each point load. And the more point loads you add in a grid, the deeper you go, the pyramid overlap more together. So with constant pressure, the wider area you have, the more there is stress deeper down, and the worse the effect gets with distance.
Completely anecdotal case in point: I live on what used to be a farm. Last year was the first where the well below the house did not carry any water despite moderate rain throughout the year. Instead, heavy rainfall in the last days carried away the top soil layers and washed them off the fields and onto streets and playgrounds.
To me, the explanation that lower layers have been compacted and now block the water seem pretty reasonable.
While it’s better to avoid it in the first place, farmers have long dealt with subsurface compaction using an implement called a subsoiler, which breaks up the compaction and restores normal drainage.
The article didn’t address that, but did speculate about the ecological intentionalities of sauropods. I suggest the authors do more field work, preferably with a horse and a moldboard plow.
Recently I read an article in which someone pointed out that while compaction in the root zone can be mitigated by better management practices, compaction at the bottom or below this are will remain until the next glaciation period.
That is very, very bad. Practically our only option at that point is to build soil up which is not something modern farming remembers how to do.
Indeed, which is why the title is so strange. Sauropods are a strange thing to compare with anyway, I would compare it with other methods actually used for working the land.
> Another way in which farmers combat soil compaction is by aeration and tilling.
The problem is that constantly aerating and tilling the soil is destroying microbiomes and fungal networks. It's one of the fundamental principles of regenerative farming. In good industrial fashion, we destroy nature (overfarming) and try solving it (chemical fertilizers) only to destroy it further (mono cultures, no biodiversity, leading to soil degradation, reduced yields), so we try to fix it again (huge machines, more mono cultures), and now these machines are destroying the soil because they are too heavy. It's time to dial back and rethink what we're doing.
Yes, there's an actual no-till movement with organic farmers as well. It's popular for two reasons:
- It's a lot less work (no tilling, less need for getting rid of weeds). Especially for private gardeners, interesting to know probably.
- You can actually get good results with it. Healthy soil means plants have an easier time (less pests and diseases, which are generally signs of plants not doing great).
Simply using nature to work for you instead of trying to against it can be a huge time saver.
IMHO there are a few positive trends in agriculture:
- farmers are starting to like some of the organic farming practices. They work and produce good results. Also the produce is more valuable.
- high tech farming is all about being smarter with resources; including water, soil, labor, energy, fertilizers, pesticides etc. Low tech, intensive farming is mostly about blindly doing things at scale. It works but it isn't necessarily very efficient.
- vertical farming is much more efficient with land and increasingly used for producing high value produce. There might be some future breakthroughs with more nutrient rich things like rice or grains but that seems to be not possible currently.
- synthetic meat grown in a lab gets rid of a lot of CO2 issues associated with cattle.
So, the agriculture sector might look very different in a few decades. Plenty of new and exciting things happening.
I don't think chemical fertiliser is a solution to overfarming; it's a way of increasing yield. Although I guess that could be what you mean by overfarming? The yield per hectare should be whatever is naturally sustained?
The idea that farmers already know this and manage it through tilling is contradicted by the abstract:
> We demonstrate that modern vehicles induce high soil stresses that now exceed critical mechanical thresholds for many arable soils, inducing chronic soil compaction in root zones below tillage depths and adversely affecting soil functioning.
I’m also skeptical that farmers are aware of what’s going on below root zones.
Programmers who frequent HN are known to be multifaceted specialists who can debunk and upend entire swaths of advanced study by only skimming the abstract. That is why we come here, to see that magic first hand.
Speaking as a farmer, the "plow pan" is an old and well known concept. While it is true that routine tillage does not reach these depths, there are various techniques, including what is known as deep tillage, to try and address the problem at those greater depths. With the advent of GPS, controlled traffic farming moved to keep the machines on the same tracks to limit the damage to specific paths in the field in recognition of the same.
Maybe the study is talking about something else, but if that's the case I'm not sure it has made itself clear. We are very much aware of what goes on below the root zone and understand the potential yield loss impact that can come of it if not managed well. We work closely with the scientific community to ensure that we are aware of these types of things.
When we bought our farm it had been conventionally farmed for decades. Not even by the biggest tractors in the world. But the compaction is real, and the hard pan that develops over time is as well. Tiling and aeration release a lot of carbon into the atmosphere, and while they offer some short term benefit, they also destroy the soil structure over time. This is why “no till” is a popular buzzword these days; people are trying to find ways to replace tiling in the effort of rebuilding soil.
This isn’t new — when “Tree Crops: a permanent agriculture” was written last century, it focused on the ever depleting top soil in the United States and elsewhere, and inspired the concept of Agroforestry.
This “as every farmer knows” is naive. Many farmers are smart and capable people but both them and the increasingly dominant ag-corporations are primarily interested in short term economic survival/success and are working within a system of often perverse incentives. Most farmers might not enjoy ruining their lands but plenty have done so, sometimes knowingly, because it works for them in the short term.
Stand close to railroad tracks when a train goes by. You'll feel the ground sink and spring back.
At the right speed and springiness of the track, the train can create a standing wave in front that builds (like a resonant frequency does) until the track comes apart.
I know that in the Netherlands this has huge implication. In the Netherlands the groundwater level is artificially maintained. Farmers have a large influence on this level historically because they don't want it to be too high or else they wouldn't be able to use their heavy equipment. But since there has been quite a drought in the summer in recent years many other parties want to increase the ground water level.
As I understand it the problem is rather (as the article disccusses and as others here have commented) the long-term damage to deeper layers of the soil, resulting in "hardpan" [1].
as a person that worked in farming analytics I can promise you the average farmer makes tons of mistakes of that kind because either lack of knowledge or planning.
They do say in the article that this is impacting root area below tilling depth, which I presume means that deeper tilling could help, but I'm unaware of whether this level of tilling involves turning a dial, or designing new equipment.
When you over produce crops you tend to plant them in narrow rows which overloads the soil hence the need to use fertilizer. Note, it's been this way since the 1940s in USA and Europe.
Or in short words we are not being effective in feeding the world and are wasting efforts on capitalistic goofs rather then using more effective solutions.
Native American Indians used a technique borrowed from South American Indians where they refused to do monoculture, instead they grew 3 to 4 crops in the same field.
If we want the future world to starve we will stay on Monoculture.
If we want to save the planet then we need to move away from Monoculture.
> Native American Indians used a technique borrowed from South American Indians where they refused to do monoculture, instead they grew 3 to 4 crops in the same field.
Are you talking about crop rotation or growing multiple crops in the same field at the same time?
Because treads are worse than tires for compaction overall. As a soils expert explained to me (phd in the subject), compaction is a function of weight, but the function is something like 0.2*(weight) (obviously it is more complex than that and depends on the exact soil type). Compaction happens only where the tires/treads touch the ground, and tracks touch a lot more ground when you turn so even though there is less damage across the field you lose all of that and more when you turn around. Not to mention tracks have to slide sideways to turn and that is bad for your topsoil.
>The whole point of tank treads is to maximize the ground surface area that the vehicle weighs on.
The treads don't spread weight much more than the wheels - look at tank treads in practice - they are somewhat loose between wheels. Most treads are somewhat loose, meaning the tension in them is not enough to be supporting tank weight. The exist to provide traction when they catch uneven surfaces, where wheels perhaps no longer make contact.
Their point is to allow the tank to catch on non-flat ground when things jut between the wheels. Treads allow grip on non-uniform surfaces.
But most of the time the weight of the tank is completely on (only a few of) the wheels.
explained a few comments above - the question isn't that of direct pressure (that could indeed be solved by using tracks), but sub-surface pressure. Probably how the overall structure is held together and distributes weight in depth under the overall vehicle surface.
In that sense, it would probably help making tractors more like ships...
This article considers stresses further down, where the load has already had a chance to spread substantially over a large are.
Loosely speaking, at some depth it's the entire column of soil below that supports the weight of the machine, and piling on more weight will exceed the uncompressed strength from the column, and so it compresses to handle the load. The problem being that compacted soil is bad for plants ability to grow there.
On our farm we would use an attachment called a ripper. It was a series of blades that would reach down 18 to 20 inches to break up the soil. Behind each blade was a 3.5 inch diameter bullet shaped slug (called a mole) that would create an underground tunnel, not unlike what an actual mole creates. We grew carrots, so it was imperative that soil compaction was limited or it would stunt the length of the carrots.
When you destroy/squeez fungus in the forest it takes centuries to recover[1]. In Prussia when they started with scientific forestry, productivity of the forrest dropped significantly after around 100 years[2].
Good times to come. I wonder why we look the other way, even when we have all the knowledge on our hands.
Two great books:
[1]: The Hidden Life of Trees
[2]: Seeing Like a State
In fact no. Bigger heavy machines do less damage than smaller ones overall. You have to look at the whole field, not just where the tires touch. Where the tires touch the ground the heavy machine is worse, but the smaller machines touch the ground in a lot more places and so do more damage.
Farmers are now using GPS to ensure all the tires that touch the field drive exactly the same place every pass, every year. Where the tires touch the ground is hardly worth farming, but the rest of the ground is undisturbed and so much healthier.
> smaller machines touch the ground in a lot more places an so do more damage.
That’s certainly possible but not a given, and I think the somewhat obvious implicit suggestion was to use smaller machines with a lower weight to surface area ratio, no? Damage isn’t a function of how many places the ground is touched at all, it’s only a function of weight per unit area.
Is it possible we could design small robots that weigh less per unit area than the large tractors? Sure, why not? We could have smaller machines with bigger tires, we could design machines with weight reducing features like propellers, we can choose to use lighter weight materials & designs for machine frames & engines. It seems like there a plenty of possibilities that are not in fact impossible.
That first one is incredible and the second looks like a more cost effective option. Most don’t realize that organic farming isn’t pesticide free but this gives farmers that option without resorting to hand-weeding.
There's also the trade-off between width of the worked area and the treaded surface made unusable for the season. If you have any tractor work steps between seeding and harvesting, you want all those runs done in exactly the same tracks to minimize waste.
A "small robots" revolution might still come, on the coat-tails of agrovoltaics: if/when someone in the right position begins thinking the panel scaffolding as dual use, doubling as a "rail network" for robotic tools. I believe this could become a feature of agrovoltaics installations as unremarkable as overhead cranes on factory floors.
This is the idea of controlled traffic. Use the same track over and over again to not compact the soil where the plants grow. An example of a large machine doing so is the Nexat. There are videos on youtube and some detail on their website https://www.nexat.de/controlled-traffic-farming/
Going larger there increase the percentage of growing soil vs track soil.
Reading articles like this always amaze me, not so much for the problem itself but for the existence of the problem and millions like it that I never even consider in my day to day. The more you know the more you realize there is so much you don't.
This article is total BS, they could actually research the yields/soil between farms that use Steiger/John Deere 50,000lb tractors tractors (or smaller) versus farms that use Big Bud or other insanely large tractors.
Truthfully ballast limit on most normal machines is around 60,000lbs for many years now which I am guessing is the realistic maximum the soil can handle and manufactures have already figured this out.
I recently read a fascinating book about trees. It was called The hidden Life of Trees.
One study they talked about in the book, tried to find out why pipes were often destroyed by tree roots. Most people assumed it was from water leaking or condensation around pipes. However, the study found that it was actually because the soil was far looser and less compact around the pipes.
It is almost impossible to really gauge all the ramifications of any choice within the analog system we live in.
It feels like there should be a more direct way to grow stuff. AppHarvest is doing something interesting. Why plant in dirt outside and rely on lossy transmission of fertilizer and water to the plant? Plus fungus, parasites, etc. A controlled environment where you can get the nutrients and water directly to the plant seems a lot more efficient. I know the capex is huge but still. We probably should all be eating less (and wasting less) food here in the US.
Mostly it's just economies of scale. Who cares if 20% of the crop is lost to random soil related problems if you can grow ten times as much stuff in dirt than in a controlled environment. Land is so much cheaper than indoor farming.
However, I think the critical thing that is going to make indoor farming commercially viable will be water prices. At some point, the heavily subsidized water in the western US is going to finish collapsing. Indoor farming lets you milk every drop of water into product. We're talking 10:1 ratios of water usage between outdoor and indoor farming.
Currently, water to grow iceberg lettuce is about 12% of the total cost in California at $216 per acre foot. Currently it is possible for those rates to triple or even quadruple in the next few years. We may be seeing a lot more indoor growing soon!
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Another way in which farmers combat soil compaction is by aeration and tilling.
It's true though that tractors are getting larger and heavier, but farmers are pretty knowledgeable about these things and usually take them into account when deciding what kind of machinery (on what kind of tires) to use for their soil, after all, if they get it wrong they may end up negatively impacting the yield of their land.
Finally, crops tend to be planted in rows for convenient mechanical processing, and while walking behind a tractor you can actually see the soil rise again after the tractor has passed, usually because the soil acts as a sponge, the tractor squeezes the water out and once it has passed the soil will spring back. It's a bit strange to realize that the ground you walk on is so springy because you normally don't notice it.
The main take is "while surface contact stresses remained nearly constant over the course of modern mechanization, subsoil stresses have propagated into deeper soil layers and now exceed safe mechanical limits for soil ecological functioning".
i.e. they state that the stresses propagate deeper into the soil, regardless of the pressure imparted on the surface.
I dont understand it exactly, but thats what they are saying. I guess its something to do with the increased overall mass being supported by and compressing the underlying soil layers, rather than the (relatively) shallow sub-surface compaction we are usually concerned about.
What if you add a similar load directly adjacent to the previous one. Pressure is same but area is added. What is the compression 1 meter underground, at the border between the plates. It's more than in the previous case, since both loads now contribute to it.
So there is a sort of load pyramid that has to form underground to support each point load. And the more point loads you add in a grid, the deeper you go, the pyramid overlap more together. So with constant pressure, the wider area you have, the more there is stress deeper down, and the worse the effect gets with distance.
To me, the explanation that lower layers have been compacted and now block the water seem pretty reasonable.
The article didn’t address that, but did speculate about the ecological intentionalities of sauropods. I suggest the authors do more field work, preferably with a horse and a moldboard plow.
That is very, very bad. Practically our only option at that point is to build soil up which is not something modern farming remembers how to do.
The problem is that constantly aerating and tilling the soil is destroying microbiomes and fungal networks. It's one of the fundamental principles of regenerative farming. In good industrial fashion, we destroy nature (overfarming) and try solving it (chemical fertilizers) only to destroy it further (mono cultures, no biodiversity, leading to soil degradation, reduced yields), so we try to fix it again (huge machines, more mono cultures), and now these machines are destroying the soil because they are too heavy. It's time to dial back and rethink what we're doing.
- It's a lot less work (no tilling, less need for getting rid of weeds). Especially for private gardeners, interesting to know probably.
- You can actually get good results with it. Healthy soil means plants have an easier time (less pests and diseases, which are generally signs of plants not doing great).
Simply using nature to work for you instead of trying to against it can be a huge time saver.
IMHO there are a few positive trends in agriculture:
- farmers are starting to like some of the organic farming practices. They work and produce good results. Also the produce is more valuable.
- high tech farming is all about being smarter with resources; including water, soil, labor, energy, fertilizers, pesticides etc. Low tech, intensive farming is mostly about blindly doing things at scale. It works but it isn't necessarily very efficient.
- vertical farming is much more efficient with land and increasingly used for producing high value produce. There might be some future breakthroughs with more nutrient rich things like rice or grains but that seems to be not possible currently.
- synthetic meat grown in a lab gets rid of a lot of CO2 issues associated with cattle.
So, the agriculture sector might look very different in a few decades. Plenty of new and exciting things happening.
> We demonstrate that modern vehicles induce high soil stresses that now exceed critical mechanical thresholds for many arable soils, inducing chronic soil compaction in root zones below tillage depths and adversely affecting soil functioning.
I’m also skeptical that farmers are aware of what’s going on below root zones.
Maybe the study is talking about something else, but if that's the case I'm not sure it has made itself clear. We are very much aware of what goes on below the root zone and understand the potential yield loss impact that can come of it if not managed well. We work closely with the scientific community to ensure that we are aware of these types of things.
This isn’t new — when “Tree Crops: a permanent agriculture” was written last century, it focused on the ever depleting top soil in the United States and elsewhere, and inspired the concept of Agroforestry.
At the right speed and springiness of the track, the train can create a standing wave in front that builds (like a resonant frequency does) until the track comes apart.
[1] https://en.wikipedia.org/wiki/Hardpan
It is more than that
When you over produce crops you tend to plant them in narrow rows which overloads the soil hence the need to use fertilizer. Note, it's been this way since the 1940s in USA and Europe.
Or in short words we are not being effective in feeding the world and are wasting efforts on capitalistic goofs rather then using more effective solutions.
Native American Indians used a technique borrowed from South American Indians where they refused to do monoculture, instead they grew 3 to 4 crops in the same field.
If we want the future world to starve we will stay on Monoculture.
If we want to save the planet then we need to move away from Monoculture.
Are you talking about crop rotation or growing multiple crops in the same field at the same time?
However they are a lot more expensive to run and maintain - eg. just think about the additional moving parts and friction.
Also it's possible they do different damage - the metal treads are not as forgiving as soft balloon tyres.
https://www.youtube.com/watch?v=0Zh3OBxh8Po
https://www.deere.com/en/tractors/row-crop-tractors/row-crop...
The treads don't spread weight much more than the wheels - look at tank treads in practice - they are somewhat loose between wheels. Most treads are somewhat loose, meaning the tension in them is not enough to be supporting tank weight. The exist to provide traction when they catch uneven surfaces, where wheels perhaps no longer make contact.
Their point is to allow the tank to catch on non-flat ground when things jut between the wheels. Treads allow grip on non-uniform surfaces.
But most of the time the weight of the tank is completely on (only a few of) the wheels.
In that sense, it would probably help making tractors more like ships...
Loosely speaking, at some depth it's the entire column of soil below that supports the weight of the machine, and piling on more weight will exceed the uncompressed strength from the column, and so it compresses to handle the load. The problem being that compacted soil is bad for plants ability to grow there.
Dead Comment
Good times to come. I wonder why we look the other way, even when we have all the knowledge on our hands.
Two great books: [1]: The Hidden Life of Trees [2]: Seeing Like a State
Because it's profitable, unfortunately.
If we get to a place where it's all AI, is there a chance that many smaller machines will become more effective than a few enormous ones?
Farmers are now using GPS to ensure all the tires that touch the field drive exactly the same place every pass, every year. Where the tires touch the ground is hardly worth farming, but the rest of the ground is undisturbed and so much healthier.
That’s certainly possible but not a given, and I think the somewhat obvious implicit suggestion was to use smaller machines with a lower weight to surface area ratio, no? Damage isn’t a function of how many places the ground is touched at all, it’s only a function of weight per unit area.
Is it possible we could design small robots that weigh less per unit area than the large tractors? Sure, why not? We could have smaller machines with bigger tires, we could design machines with weight reducing features like propellers, we can choose to use lighter weight materials & designs for machine frames & engines. It seems like there a plenty of possibilities that are not in fact impossible.
A "small robots" revolution might still come, on the coat-tails of agrovoltaics: if/when someone in the right position begins thinking the panel scaffolding as dual use, doubling as a "rail network" for robotic tools. I believe this could become a feature of agrovoltaics installations as unremarkable as overhead cranes on factory floors.
Going larger there increase the percentage of growing soil vs track soil.
https://en.wikipedia.org/wiki/Big_Bud_747
Truthfully ballast limit on most normal machines is around 60,000lbs for many years now which I am guessing is the realistic maximum the soil can handle and manufactures have already figured this out.
One study they talked about in the book, tried to find out why pipes were often destroyed by tree roots. Most people assumed it was from water leaking or condensation around pipes. However, the study found that it was actually because the soil was far looser and less compact around the pipes.
It is almost impossible to really gauge all the ramifications of any choice within the analog system we live in.
However, I think the critical thing that is going to make indoor farming commercially viable will be water prices. At some point, the heavily subsidized water in the western US is going to finish collapsing. Indoor farming lets you milk every drop of water into product. We're talking 10:1 ratios of water usage between outdoor and indoor farming.
Currently, water to grow iceberg lettuce is about 12% of the total cost in California at $216 per acre foot. Currently it is possible for those rates to triple or even quadruple in the next few years. We may be seeing a lot more indoor growing soon!
Totally exciting!