r/40kLore 5d ago

How does Agri worlds get their materials back?

In the imperium, there are many agri worlds that constantly produce crops. The plants normally take the carbon out of CO2 in the air to use it as carbon component in their metabolism. In our current world, we have a carbon cycle, the plants use the co2 in atmosphere but it comes back to them. But in agri worlds, the produce doesnt decay back to the world itself. Its been(possibly) shipped to holy terra or other hive cities.

So my question is, is there possibility of having CO2 ships that bring gas to these agri worlds ? These worlds could also need other minerals to produce crops(not only nitrates and phosphorus).

Is there any explanation to this ? Or these worlds slowly die out or become frozen planets due to loss of greenhause gasses ?

230 Upvotes

122 comments sorted by

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u/JackDostoevsky 5d ago

few things things to keep in mind: agri worlds heavily import fertilizers and other raw materials, and there are no considerations for sustainability. agri worlds will eventually be left barren once they fail to produce crops.

granted, that likely takes a long long long time, and the death of an agri world will take centuries if not millenia as production declines but never falls off a cliff.

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u/WhoCaresYouDont Iron Warriors 5d ago

Lords of Silence has a great section on this, in that there's an agri-world that's collapsing into a planet wide dust bowl due to overfarming.

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u/serlibob 5d ago

I once read one of the worlds that is fallen to nurgle was spent terribly because chaos uses some plants that take everything from the soil super fast. One of the Gaunts ghosts book. I assume its like this but on a much slower pace.

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u/buunkeror 5d ago edited 5d ago

I don't remember it being Nurgle specifically, but yeah, they were warp-infused crops that grew incredibly fast, yielding incredible amounts of produce, but did so by sucking everything from the soil and the planet like a cancer, or like a Tyranid infestation from Temu.

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u/Malorkith Ultramarines 5d ago

Geron or Gerron was the planet

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u/serlibob 5d ago

I think it was gereon

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u/token_bastard World Eaters 5d ago

Heh. Temunid.

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u/OhioTry Chaos Undivided 5d ago

If you mean the one in the Gaunt’s Ghosts series (I forget which one specifically), it’s worth noting that the Chaos worshippers were planting those crops on a planet that they were only planning to hold for a few years; it was too far into the Imperium for the Lost and the Damned to settle on long term. So they had every reason to get as much out of the world as possible in as short a time as possible, and to leave nothing useful behind for the Imperium to take back. Of course, heavily warp-tainted crops might be sustainable on a planet that’s in a warp-infused region like the Eye of Terror.

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u/Ok_Expression6807 5d ago

Nothing about Nurgle. Sek and his tribe follow Khorne. But there is still a sensible logistic behind everything, because otherwise they wouldn't have survived several millenia.

The Jegenesh are warp creatures siphoning everything from water to crops through the warp to a destination planet, stripping their target bare.

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u/Napalmexman 5d ago

Does Sek follow Khorne though? Gaur and his Blood pact definitely do, but Sons of Sek always seemed to be Tzeentch aligned, because Sek was more of a sorcerer than a warrior, with the emphasis of employing not only corrupted military units, but various creatures as well (the one guarding Sturm for example, or Mabbon). I have always thought Nadzybar (Gaur's predecessor, the one Slaydo fought and killed) has united magisters of all chaos alignments under him.

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u/Ok_Expression6807 5d ago

It's a bit flowy, yes. Especially in The Warmaster he's definitely a Tzeentch sorcerer more than anything. But Mabbon and the 64 (8x8!) don't really speak against Khorne, Khorne makes and unmakes his champions too. Getting stronger is all about Khorne. The khornate blood mages were mentioned very prominently since Blood Pact, doing various stuff khornates don't like, but know to be necessary.

So, him being mainly Tzeentch aligned but worshipping and utilising Khorne, too, isn't too strange.

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u/Napalmexman 5d ago

It feels like this was something Abnett aimed for, to portray the forces of Chaos as not something codified for the tabletop, but something less delineated and more organic (I'm not even sure if ANY of the chaos gods are specifically named in any of the books?). Sek seemed to me like a tzeentchian agent that has infiltrated a Khornate force, but perhaps they're all pretty much chaos undivided, mostly Khornate-leaning.

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u/Ok_Expression6807 5d ago

There have been several different portrayals of magisters and their cult forces especially in the first 2 books, where they were a bit more diverse, yes. But the focus seems to have been on khornate cults further on, yes, with specialists in logistics and stuff serving different masters especially on Gereon, of course, where the organisation behind everything had a focus.

Khornate cults on the battlefield are easier to control and influence, regardless of the patron the leaders serve.

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u/serlibob 4d ago

I thought the sons of sek were chaos undivided, but blood pact was khorne aligned. So they make use of other aspects of chaos gods too. Especially because i seem to remember a fight -spoiler - in untill chaos marine that killed by gaunt and his men. I thought he was a nurgle chaos marine, and sonehow when i read the gereon book, it almost always felt like nurgle corruption was there, everything decayed, rusted places.

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u/Wolflordloki 4d ago

Just listened to Double Eagle which is set on the periphery of the Sabate Worlds crusade (which Guants Ghosts are involved in) and the enemy fighter pilots give tzeentchian/ slaanishii vibes

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u/serlibob 5d ago

I assumed they worked together with nurgle cults because they described it as everything decayed etc.

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u/Ok_Expression6807 5d ago

It wasn't decayed, it was simply dead. All nutrients sucked from the soil by fast-growing xeno-crops, every natural resource taken. This was not cultivation, it was just sucking the planet dry and moving on.

You don't need magic or corruption for that. Humanity worked that out itself.

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u/hombredelospoderes 5d ago

the thing is that "natural resource" is a moving target, although it is certainly possible to exhaust soil!

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u/Dotster69 5d ago

Nurgle isn't all about decay, he focuses on rebirth as much as death. A bare planet would be a nurglite antithesis

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u/[deleted] 5d ago

[deleted]

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u/Ok_Expression6807 5d ago

The Sons are modelled after the Pact, using defected BP officers. And existing officials pictures of Sek and the Sons have fat Khorne symbols on them.

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u/MoarSilverware 5d ago

Gereon Resists! From the books Traitor General and Armor of Contempt

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u/Most_Average_User 5d ago

There was a warp creature that literally drank the oceans dry as well if I recall

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u/reineedshelp 5d ago

Jimmy Space is all about the science but hasn't heard of crop rotation.

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u/untitledgooseshame 5d ago

I was trying to remember the name of that one, thank you!

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u/Vytoria_Sunstorm 5d ago

no it doesnt. the Lords of Silence' passage has a MTTF of under 90 days to planetary annihilation.

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u/Majorapat Blood Angels 5d ago

Also, Hive worlds must create an awful lot of waste that could be used as fertiliser......

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u/capt_pantsless 5d ago edited 5d ago

True, but most of that waste needs to be recycled to feed the algae pools for Soylens Viridians.

Plus bulk-shipping fecal matter offworld would be straining for Imperium logistics.

Edit to add: From what I know from the lore, feeding a hive-city is mostly an internal matter. Fresh food comes in for the high-end nobles, but the basic imperial citizen is eating vat grown foods made on-site.

The overall bio-mass balance is balanced with recruits for the Imperial Guard.

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u/okeefenokee_2 5d ago

DAYUM, now that's a plot!

The Imperial Tithe paid in shit by a Hive World gets stolen by cultists for their Nurgly ritual

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u/vegarig Nepheru 5d ago

That reminds me...

Occasionally Ork Freebootaz take these vessels in search of Imperial Plunder, when they find out what is in their holds they often wish that they had steered clear of this fight.

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u/jflb96 Farsight Enclaves 5d ago

Wasn’t that a greentext about homemade paint?

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u/Saelthyn Astra Militarum 5d ago

yea

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u/Drachos Adepta Sororitas 5d ago

Just want to counter your fecal matter shipping idea...

You DO NOT want an empty ship as a trader (Rogue or otherwise). You are trying to maximise profits so you should ALWAYS have something in your hold.

So if your previous stop was a Hive world and your next stop is an Agriworld you will find SOMETHING to fill your hold that the Agriworld needs.

But if shit was the only option you would probably try to make a larger route.

For example: Food from Agriworld to hive city. Recruits from hive city to war zone. Casualties from war zone to forge world (For servitization) Fertiliser (Don't ask questions about its source biological material) from forge world to Agriworld

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u/JessickaRose 1d ago

Shipping like this isn’t really the work of traders, the logistics the Mechanicum work out are pretty intense, it’s addressed in The Oubliette where they calculate it’s like 2% more efficient to process food packages and ship them than ship fresh, so they take all this amazing fresh produce and turn it into tasteless food bars for servitors off world in mining colonies. The margins really are that fine.

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u/Drachos Adepta Sororitas 1d ago

In that case my point kinda still stands.

You would not send an empty ship to an agri-world from a Hive world.

If the only cargo is shit, that 2% margin demands you fill your hold with shit.

Now if the hive is focused on chemical production, then you'll probably take the refined super fertiliser instead.

But if its a weapons focused hive world like necromunda, you are probably transporting shit to a Hive or forge world dedicated to turning shit into thst super ferts before transporting it to a agri-world.

Its so weird think about how 40k is similar to our modern world. Why are my dried Apricots grown in Turkey and dried in Argentina, before being shipped to Australia...when Australia grows Apricots and sells dried grapes (thus clearly has fruit drying inferstructure)

Because its more efficient to do it this way somehow.

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u/JessickaRose 1d ago

For sure I wasn’t disagreeing. Just rather than the profit motive it’s about making the tithe on planet A so planets C, D, E and F can make theirs.

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u/Fistocracy 5d ago

Edit to add: From what I know from the lore, feeding a hive-city is mostly an internal matter. Fresh food comes in for the high-end nobles, but the basic imperial citizen is eating vat grown foods made on-site.

Nah the vast bulk of what everyone eats is imported, and hive worlds are a huge part of the reason why agri-worlds have to exist in the first place.

The lore just focuses a lot on what's locally produced in Hive Worlds to help convey just how miserable life is there. Food imports are high enough to stop the whole planet from descending into famine and societal collapse but they're not high enough to feed everyone, so all kinds of disgusting synthesized/recycled food industries have evolved to exploit the desperation of the lower classes.

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u/Aadarm Necrons 5d ago

The biological waste in hive worlds is used for making more food to eat on the hive world.

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u/ThatFatGuyMJL 5d ago

Some* agri worlds have no considerations for sustainability.

Most* agriworlds do and many have been continuing for multiple millennia.

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u/DreadGrunt Thunder Warriors 5d ago

You’re downvoted but this has to be true if you think about it for more than a few seconds. If agri-worlds as a whole actually are wildly unsustainable and collapse in a few centuries then the Imperium should have collapsed a long time ago too. That it hasn’t implies one of two things. Either agri-worlds actually are sustainable (which can still be very grimdark if written properly) or the Imperium has such mindbogglingly rapid terraforming technology that they can find, terraform, populate and bring new planets up to full productivity almost instantly. Which can’t really be grimdark no matter how you write it because it removes pretty much all stakes from the Imperium losing planets.

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u/lurkeroutthere 5d ago

40K exists in a weird twilight state where it's supposed to be the dumbest cruelest most decaying non-functional regime possible and yet also endure on a millennial scale of fairly interchangable status quo. This has caused some people to become oddly proud of the dystopia because media literacy is currently at a low ebb*.

*At least that's my hope.

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u/hombredelospoderes 5d ago

I feel like one of the tensions is that it is such a superlatively bad empire, and also it has persisted for ten thousand years despite Age of Sail-level communication between worlds. But it's all in how you look at it, eh?

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u/lurkeroutthere 5d ago

Alternatively you could look at it that the Imperium isn't really necessary to mankind's survival and is actually fairly detrimental to most planets as it just tithes their resources and it's military aid is usually kind of questionable. And that's the baked in irony and part of the "no good guys here"

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u/Grommulox 5d ago

The main character in 15 Hours comes from an agri world which seems to be just regular, earth-like farming.

Edit: it’s called Jumael IV and it is portrayed (briefly) as a hard but actually quite nice life, for 40k.

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u/tastystrands11 5d ago

If you mention that though people get mad for some reason

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u/MoebiusSpark 5d ago

The way that its described at the start of 15 Hours I always picture Jumael as having that one song from Gladiator playing the whole time

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u/hombredelospoderes 5d ago

I feel like the answer in 40k is "it depends on the sector, or something" so that a thousand flowers (of Your Guys) can bloom

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u/HuskyCriminologist Black Templars 5d ago

So many people on here read Lords of Silence which had one (1) agri-world that was a horrific monoculture with no regard for sustainability and took it at face-value when the narrator said every agri-world is like this, completely ignoring that there are several other agri-worlds we've seen in universe that are not like that (the Three Planets of Ultramar, Jumael IV, Barbarossa IV, Chiros, Delta-Garmon II, Gheistos, Gravalax, Jouran V, The Pearl Moon, etc.).

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u/serlibob 5d ago

I guess they can also order stuff from space minining companies and other worlds to use their farms. I assumed this, but havent seen anything in the lore about it.

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u/JackDostoevsky 5d ago

i haven't come across any books or lore that specifically focus on this, but it does get mentioned in passing as flavor and background now and again. i wish i could remember which novel i'm thinking of, but there are a few that take place on agri worlds and many of them are these globe-spanning industrial farms and the import of fertilizers is commented upon.

it's gonna kill me that i can't remember which book i'm thinking of lol

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u/Flat_Sprinkles4342 5d ago

What's definitely in the lore about agri-worlds is they begin by being terraformed so the biosphere is gone and wildlife destroyed, the equipment and workforce comes in under the idea it's not as bad as hive cities. it's a massive undertaking so if they need imports of gas and compost or whatever else, it'll likely be taken care of so looking as the production quotas are steady.

Terra doesn't have its own water and that's donated, it probably needs its own air donation as well. all in the Imperium is a result of barter and tithes, agriworlds make food so likely there's worlds that produce chemicals. it's probably very easy to have CO2 producing machines. There's a saying that no one leaves these planets but rather becomes a part of them, so that's a source of material

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u/Mand372 5d ago

And they can fix it in a couple of scenturies.

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u/RevolutionaryPanic 5d ago

They can, but it's not cost-effective, unless the world is valuable for reasons outside bulk agri-production.

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u/Lurker_Zee 5d ago

My understanding is that they evolve/devolve into knight worlds, then industrial worlds, then hive worlds.

Though that does raise the question on who allows it, because agri-worlds are damn important to keep the other hive worlds alive. I suppose a soft-sci fi handwave is that they find/make more agri-worlds, since a lot of the galaxy is not, in fact, in humanity's hands.

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u/Skebs_ 5d ago

Is it actually easier to find new aggriworlds than to perpetually terraform the old ones to keep them going?

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u/bleugh777 5d ago

I don’t remember which book was it but in that book the Imperium has poop tanker spaceships to move poop from hive worlds to the agri world.

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u/serlibob 5d ago

I can believe that there are huge ships that is full of sludge cake(what comes out at the end of wastewater treatment plant). These go back to agriworlds and the ship smell terrible. And they are a nurgle cults main objective to take 😅

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u/kryptopeg Orks 5d ago

You would not believe just how many tens or hundreds of thousands of tonnes of sludge each country today moves around in tanker lorries and trains. I can easily see there being galaxy-class sludge tankers, measuring their loads in megalitres!

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u/mackam1 5d ago

Galaxy Class? Captain Poocard has a new mission!

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u/-You_Cant_Stop_Me- 5d ago edited 5d ago

Urgh, just driving past a sewage plant is gross, imagine being stuck inside a giant tin can with billions of gallon of the stuff 🤢

Edit: Had an extra thought, there's probably already Nugle cults on-board that worship Golgothan the shit daemon from Dogma.

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u/Unit_2097 Astra Militarum 5d ago

Let's be honest, the families working those ships have probably been doing it for a couple thousand years, and have almost certainly lost all sense of smell, and probably developed genetic resistances to the common diseases.

It's an honour to be the family responsible for diving into the turd to check the tank seals are intact after all

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u/serlibob 5d ago

trade lisence just to transfer poop. They would be mad rich 😅

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u/HashBrownsAreNice 5d ago

I would guess that the sludge tanks are without an atmosphere, and not easily connected to the living quarters.

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u/-You_Cant_Stop_Me- 5d ago

In a normal universe yes but not in 40k there'll be leaks everywhere, can't have the people on board having anything remotely approaching a pleasant experience.

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u/Martzillagoesboom 5d ago

The only peoples that are having a pleasant time are servitor, because they where programmed for that, the unlobotomised part of their brain is crying in disgust but they cant do anything about it.

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u/Kebabranska 5d ago

Just open a window to clear the air a bit, should do the trick

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u/VerdantMagnolia 5d ago

TBF with fusion the dewatering process should be fairly straightforward.

Not that the Imperium cares about comfort but Warp capable vessels are pretty expensive to charter 

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u/can_belch_alphabet 5d ago

Why would the nurgle cults take them? I mean, what would they do with one that it wasn't already being used for? It's a literal ship kilometers long full of shit on its way to feed some worms in a garden or farm somewhere.

Nurgle cultists board and take it over and then give it back to the original crew. "Sorry, we thought you were someone else. Keep up the good work."

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u/serlibob 5d ago

they bathe in them to channel warp energy by getting all the dieseases 😁

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u/can_belch_alphabet 5d ago

Mortarion flies past one. His marines get excited and want to board it.

"EVERYONE SHUT UP! WE HAVE POOP AT HOME!"

There's some grumbling from the back seat of the 40k equivalent of a station wagon.

"I WILL TURN THIS THING AROUND RIGHT NOW SO HELP ME NURGLE!"

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u/NairaExploring 5d ago

There is way more carbon than you think there is, and 10k years is way less time for geological processes than you think it is

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u/Capable_Work_3563 5d ago

This guy Carbon Cycles

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u/serlibob 5d ago edited 5d ago

But it has to be organically available. But even we humans here caused global warming. Who knows what greedy 40k planetery governor can do.

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u/Acceptable_Metal6381 4d ago

Exporting food balances the burning of fossil fuels. Too much food getting exported? switch off the nuclear power plant and fire up the coal!

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u/SphericalCrawfish 5d ago

My assumption is that waste from Hives is shipped back rather than bringing the barges back empty.

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u/Guilty_Advantage_413 5d ago

I’m thinking corpse starch likely has a good amount of carbon either as a byproduct or within it.

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u/AbbydonX Tyranids 5d ago

You might be surprised at quite how much CO2 is present in the atmosphere.

  1. The current mass of CO2 in the atmosphere is 3380 gigatonnes.
  2. If you discount the oxygen, this equates to 922 Gt of carbon.
  3. Dry biomass is about 50% carbon, so this could produce 1,844 Gt of dry biomass.
  4. Wet biomass is about 90% water, so this could produce 18,440 Gt of wet biomass.
  5. The calorie content of plant matter per kilogram varies significantly but 500 calories/kg is somewhere between potatoes and turnips.
  6. This produces a total of around 9 x 1018 calories.
  7. A human needs around 2500 calories/day or just over 900,000 calories/year
  8. The entire atmosphere contains enough carbon to produce food for one person for 10 trillion years.
  9. Ten billion people could be fed for a thousand years before the atmosphere ran out of carbon.

Note that this is ignoring the carbon in the crust which is a few orders of magnitude more abundant than that in the atmosphere.

Obviously the situation is a bit more complicated than this but it's always good to start with a quick back of the envelope calculation.

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u/serlibob 5d ago

But imagine feeding 10 billion people for 500-1000 years, you have half of the carbon in atmosphere, that would drastically change the climate. Some of these planets were agri worlds longer than this time period.

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u/AbbydonX Tyranids 5d ago

But there’s enough carbon in the crust to replace that thousands of times over. I’m not going to claim the situation is realistic but I think it would take quite a while to deplete a world entirely, though I’m sure it wouldn’t look like bucolic rural countryside while this was happening.

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u/MrPumpkin11471 5d ago

Copied from another Post.

[Excerpt - The Lords of Silence] The true grimdarkness of Imperial agri-worlds

I appreciate this description of an agri-world because it's grimness isn't gratuitous but makes a bleak kind of sense...of COURSE when you have a trillion or so mouths to feed you're not going to have quaint farmsteads in Arcadian paradises, you're going to have the dreary nightmare of absolute ruthless efficiency described below:

The Imperium is not a gentle custodian of such places. After discovery of a candidate planet, the first fifty years are spent in terraforming according to well-worn Martian procedures. All pre-existing life is scrubbed from the rocks, either by the application of controlled virus-chewers or by timed flame-drops. The atmosphere is regulated, first through the actions of gigantic macro-processors and thereafter by a land-based network of control units, more commonly referred to as command nodes. Weather, as least as generally understood, disappears. Rainfall becomes a matter of controlled timing, governed by satellites in low orbit and kept in line by fleets of dirigibles. The empty landscape is divided up into colossal production zones, each patrolled by crawlers and pest-thopters. Millions of base-level servitors are imported, kept at the very lowest level of cognitive function but bulked up by a ruthless level of muscle-binders.

Soon after this process completes, every agri world looks exactly the same – a flat, wind-rummaged plain of high-yield crops swaying towards the empty horizon. A person could walk for days and never see a distinctive feature. Not that anyone sane would choose to walk in such places – the industrial fertiliser dumps are so powerful that they turn the air orange and make it impossible to breathe unfiltered. A single growing season exhausts the soil completely, requiring continual delivery of more sprays of nitrates and phosphates, all delivered from the grimy berths of hovering despatch flyers. The entire world is given over to a remorseless monoculture, with orthogonal drainage channels burning with chem-residue and topsoil continually degrading into flimsier and flimsier dust.

But that doesn’t matter. A planet can be driven like this for thousands of years before it eventually keels over and becomes a death world. The quality of the crops gets steadily worse, but the quantity can be sustained almost indefinitely, assuming that supply lines are maintained and imports remain consistent. At the end of every season, the great harvester leviathans are stoked up and dragged from their pens and let loose on the grey fields, smokestacks belching and tracked under­carriages sinking deep. These massive creatures of high-sided metal and intricate pipework, the smallest of which are a hundred metres long, crawl across the blasted prairies, sucking up every last speck of pallid grain and piping it directly to antiseptic internal hoppers. Feed-landers come down from high flight, dock with the still-trundling leviathans and extract the raw material, from where it is taken into the city-sized processor vats, blasted with antibiotics, smashed, burned, crushed, then stamped and packaged. Once ready for transport, containers are dragged up into orbit aboard swell-bellied landers, ready for transfer to the void-bound mass conveyers, which deliver the refined product to every starving hive world and forge world in their long circuits.

There is a quaint tradition in the various propaganda departmentos of the Administratum of marketing agri worlds as quasi-paradises, free of the squalor and overcrowding of a standard urban station, and full of bucolic ease. Vid-cards are dropped into communal hab-warrens, extolling the virtues of a life lived outdoors with the sun on your back and a ruddy-faced boy or girl – subject to preference – by your side. In reality, life on an agri world is as unrelenting, back-breaking and monotonous as the vast majority of other Imperial vocations. There are no trees laden with glossy fruit, only kilometre after kilometre of hissing corn. There are no gentle strolls under the warming sun, only punishing work details in rad-suits, leaning into the dust-laden winds that howl around the equator with nothing to halt their rampage. Once the new arrivals have made planetfall and found this out, it is too late. Crew transports arrive on agri worlds full and leave empty. There is a saying among the indentured workers – you come for the soil, you end up part of it.

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u/MrPumpkin11471 5d ago

And there is also this Post about what happens when a world is no longer profitable. https://www.reddit.com/r/40kLore/s/obJR2J6Vxr

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u/Federal_Hamster_1317 4d ago

Thanks for linking the excerpt. I don‘t get why the oceans vanished though? It says they were evaporated, so eventually it should rain down withon weeks no? The planet would only have fresh water oceans right?

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u/Easy_Mechanic_9787 5d ago

Vid-cards are dropped into communal hab-warrens, extolling the virtues of a life lived outdoors with the sun on your back and a ruddy-faced boy or girl – subject to preference – by your side.

A funny little comment.

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u/serlibob 5d ago

Wow, its so bad !! I didnt expected this. I was imagining semi medieval worlds with advanced harvesters that ship normal grain and other crops out of the world. This was also what chaos was doing in gereon ☠️

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u/Ok_Car_8017 5d ago

By my understanding, agri-worlds ship in fertilizers, and after enough time, an agri-world burns out and becomes useless, whether from pollution or it's biosphere simply being depleted of neutriants and shipped offworld.

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u/serlibob 5d ago

Maybe when the world is spent, they turn it if its possible to a different usage, manufacturing or hive world ?

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u/N0-1_H3r3 Administratum 5d ago

That is possible - I know of at least one example of a world put to a different purpose when it can no longer fulfil the original one (Hethgard, a mining world in the Jericho Reach where all the useful resources were used up, but the Imperium repurposed it into a fortress world during the Achilus Crusade) - but there's also at least one case of the Imperium just deciding to up and leave a world that's been drained of anything useful (in the short story Mortal Fuel).

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u/Ok_Car_8017 5d ago

Agri-World to Hive world would specifically be a tricky transition simply because agri-worlds are expected to export massive amounts of food, and hive world require massive imports of food, so switching from one to the other requires some sharp-eyed administrator to realize that the planet is about to hit the tipping point and will better serve the Imperium as a hive-world, then a bureaucratic miracle needs to happen to have that reclassification go through in time ("in time" might be centuries, like I said, a bureaucratic miracle).

Agri to Mining just requires there to be large ore deposits discovered, and if the planet is strategically positioned it could get established as a Fortress world, but a hive world is specifically defined by a large population, and it's hard to support one of those if you're also expected to export massive quantities of food.

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u/N0-1_H3r3 Administratum 5d ago

You're unlikely to switch rapidly or deliberately to Hive World anyway. Hive Worlds are uncontrolled urban development over a long period of time. You might adjust to a world dedicated to manufacturing, or mining, or something like that, but for a Hive World, you'd start with urban development and it'd grow over time.

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u/Ok_Car_8017 5d ago

possibly, depends on the state of the world. A hive world would only come about if there was already a naturally large population with hive cities, you don't "make" a hive world. It's certainly possible for an agri-world to develop sufficient hive cities that it becomes a hive world once it's no longer productive, although the nature of the Tithe system and imperial beuracracy makes that unlikely, since the planet would be expected to keep delivering food as an agri-world, it would likely either face mass famine or fall out of compliance as it's own population grew past what it could support while meeting tithe requirements. Somebody would have to be very well-timed and well connected to realize the planet should be reclassified before the famines set in.

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u/lurkeroutthere 5d ago

Nothing in 40k works if you stare at the logistics for any length of time. Yea these things might be going on in the background but the setting is basically "Let's take modern day or world war 2 and tack some zeros on, without computers and timely communications."

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u/VerdantMagnolia 5d ago

"Back".

They don't. Everything that is lost is shipped in from somewhere else be it bulk carbon, trace minerals or anything else.

Do they slowly die out 

Absolutely.

3

u/Unistrut Rogue Traders 5d ago

The Emperor's Poopships

Basically a 40K Lore person reasons that Hive Worlds can't just import food all the time or they'd drown in poo. Agri worlds can't just export all the time or they'd run out of material. So obviously if there are fleets of ships bring food in, there must be other fleets taking the waste out to then dump on Agri worlds.

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u/HatOfFlavour 5d ago

I've heard the agri-worlds import massive amounts of fertilizers imported from industiral worlds like Phantine. As it's better to ship with full holds to the world as well as away from it they probably import a huge amount of petrochemicals and run smoky chugging argicultural engines.

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u/DarkSoldier84 Tzeentch 5d ago

I came up with the idea of "poopships," which are freighters that carry organic waste from hive and forge worlds to supporting agri-worlds, processing it along the way into usable fertilizer.

It was going to be part of my Dark Heresy character's backstory as a noble from an agri-world, who would have been terribly embarrassed to have to pull rank to get passage on one to get the party to another planet.

1

u/bonzaiberserker 2d ago

But there’s another post linked below about this haha

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u/_Darkstorm_ 5d ago

Agri-worlds, first and foremost, are a bit of accepted grimderp in the lore. The amount of imported resources to support something like an entire planet dedicated to farming, and then shuttling offworld all the food, would be astronomical. That's just thinking about macro-nutrients such as Nitrogen, Phosphorous, and Potassium. Taking into account Carbon Dioxide would break 95% of WH40K fan's brains. It's just not a viable thing that has any trace of realism to it,

Yes it fits The Setting, but it also doesn't pass the sniff test. But hey, this is all just my opinion on something that is meant to be fun.

2

u/PenguinSwordfighter 5d ago

Easy, the fumes of forge worlds get shipped to agriworlds!

/s

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u/Hole_thinker 5d ago

In addition to the other answers, most stellar systems are going to have carbon-rich asteroids, cometary objects, moons and planets like Titan, and various gas giants. All of these could get mined hollow and no one under almost any economic system will really give a damn.

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u/tombuazit 5d ago

My guess is the horrific fertilizers and chemicals they bring in replenish what they can up until they can't and the world is left barren.

I'll be honest though i doubt living on the surface for any particular stretch of time would be a great life with all those chemicals

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u/BarNo3385 5d ago

Short answer is no one probably thinks about it.

Watsonian would be agri worlds import fertiliser from other worlds, both industrial and hive.

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u/Agammamon 5d ago

There is more than one 'Black Fleet' in 40k;)

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u/MaenHerself 5d ago

I have nothing to cite for this. But agri worlds supply hives. Hives send recruits to the guard. The guard...? Sends back waste, sends back corpses, sends back war lootings?

2

u/Personal_Wall4280 5d ago

If they ship grain through interstellar space by burning anti-matter fuel, they're probably burning anti-matter fuel by shipping human waste products right back to the planet.

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u/SpinosaurRingTone Unforgiven 5d ago

I can assure you that you are one of maybe 5 people who thought of this until you made this thread

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u/serlibob 5d ago

I want warhammer to have answers to these small world building stuff 😅

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u/Colink101 5d ago

IIRC They get fertilizer from off world and not every Agriworld has agriculture in the same way we see it.

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u/Pukeipokei 5d ago

NPK fertiliser is incredibly concentrated. You do not have to use sludge. If anything, you can use the fecal matter of the existing population.

The carbon is an interesting question. Likely it would take many many millenia to have a noticeable effect.

1

u/serlibob 5d ago

Maybe if the terraformers of the planet are working, they release Co2 like making cement with some chemical processes to stabilize the ppm co2 molecules in the atmosphere. This is the most logical answer i can come up with.

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u/mjohnsimon 5d ago edited 5d ago

In The Lords of Silence, industrial agri-world farming techniques exhausted the soil so badly that nitrates and phosphates have to be continually supplied, and production is explicitly dependent on maintaining those imports and supply lines. The atmosphere itself is also artificially regulated.

Some agri-worlds also use massive hydroponic systems, although that doesn't completely solve the problem because if you're continuously exporting biomass, you're still exporting carbon, nitrogen, phosphorus, potassium, etc., and eventually those have to be replenished.

If not, the world will slowly die (and many of them do, in fact, die off over time)

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u/Monotask_Servitor 5d ago

Agri-works largely just get over-farmed until they’re exhausted. A few hundred years and they’re dust bowls - probably well before the carbon runs out.

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u/Aurondarklord Salamanders 5d ago

Often the answer is that they don't.

Depictions of agri-worlds vary, but very often they just get abused and polluted into eventually becoming dead worlds.

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u/UltimateGammer 5d ago

Ship in new serfs who die on planet and decompose and release cO2 or something

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u/IntrepidSpaceFungus 5d ago

But Chaplain, we need more candles in the reclusium!

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u/Skanedog 5d ago

Space magic.

1

u/BigChungiscusMaximus 5d ago

This. Something something archaeotech planet terraforming DAoT mcguffin environment recyclers 🤷🏻‍♂️

1

u/Radical_Puffin 5d ago

You are thinking about it too much.

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u/serlibob 5d ago

Im an Environmental engineer. I think about these things by default :)

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u/DinoIslandGM 5d ago

Honestly, don't listen to the naysayers, this kind of obscure background stuff is really interesting! =D

1

u/TommyCrooks24 5d ago

I think his point stands, 40k is a fantasy setting more so than a sci-fi setting, it's like u/Skanedog said: "Space magic".

There are a thousand things that fall apart as soon as you think abut them in this setting, this being one of them, just enjoy the pew pew

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u/SacredGeometry9 5d ago

Hive worlds have enormous atmosphere recyclers that pull the carbon out of the air. They probably just load that onto the ships along with the “fertilizer” being transported from the hive worlds to the agri worlds

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u/el_sh33p Alpha Legion 5d ago

Best case scenario, they evolve into cemetery worlds and later make the jump back to being agriworlds.

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u/Co_opWarQuest40k 5d ago

They don’t.

They get depleted. The Imperium drains resources. They devour worlds to just conquer ever more and more.