The Peecyclers
nytimes.com
nytimes.com
https://www.cannagardening.com/how_ammonium_nitrate_ratio_af...
However, nitrate has many other practical uses, and in industrial Europe before the invention of Haber-Bosch, a major use was gunpowder manufacture (the ingredient saltpeter, potassium nitrate KNO3). An entire industry existed, based on taking animal and human urine (and other materials, like rotting animal carcasses) and processing it in a certain manner to encourage its conversion to nitrate crystals, typically involving beds of wood chips which would become covered with a frost of potassium nitrate crystals. The British government passed laws about the storage of urine for the king's 'petermen' to come and collect for this purpose. Here's a technical manual from 1862 on the process, from start to pure potassium nitrate (which in turn, could be converted to the important industrial chemical, nitric acid):
https://docsouth.unc.edu/imls/lecontesalt/leconte.html
Whether or not this widespread practice had anything to do with the origin of the British phrase 'taking the piss' is a mystery to me.
"De Monet", "Deee Monet"!
Let's say I need 200 kg/ha of a 12-6-6 NPK fertilizer for post-sowing 10 ha of some crop, like corn. (This is a little short of 180 lb/ac for a total of ~25 acres. I'm in Europe, and I don't know what would be a typical value for the US).
This fertilizer has 12% w/w of total nitrogen, so for the total area my needs are 240 kg of nitrogen (~530 lb).
An adult will produce an average of 1,4 L (0.37 gal) of urine daily, with a nitrogen content of 8,83 g/L, so this means a total of 12,36 g/day, or 4,5 kg/year (~10 lb/year).[1]
So I'll need the urine that 53 people pee for a whole year for this single crop. A six tower pivot has something around 4 or 5 times that area. And this area can be used twice a year for different crops. The average US farm has 445 ac.[2]
[1] https://en.wikipedia.org/wiki/Urine#Characteristics [2] https://www.statista.com/statistics/196106/average-size-of-f...
How many people this would feed is hard to tell, because it depends on the kind of corn. Some corn is meant for human consumption, some other for livestock feed (which in turn is meant for human consumption. But as a rough estimate one can add these two to find an order of magnitude.
In 2008, the USDA broke down the usage for maize, with 133,4 Mton (5250 Mbs) for livestock and 8,3 Mton (327 Mbs) for human consumption. That year, the US population was around 303.5 million people, so that gives an average of 467 kg (1030 lb) a person each year.[3][4]
So those 10 ha would produce enough corn for 240 people for a whole year.[5]
[1] Assuming around 15% moisture content.
[2] https://www.dtnpf.com/agriculture/web/ag/crops/article/2021/...
[3] https://en.wikipedia.org/wiki/Maize#Human_food
[4] https://www.populationpyramid.net/united-states-of-america/2...
[5] I ended up doing the calculation in imperial units, to minimize rounding errors.
- First of all, urea as a fertilizer is not completely effective, because some of it will be drained. Urea can be treated for slow release, but this requires processing. And even in this case, some of it will just be degraded by bacteria (some bacteria will turn it into compounds that plants can use, but generally urea content will fall with time).
- I used total nitrogen from urea, but in reality a part of that nitrogen does not come as urea.
- I also used average yields, which depend on the usage of more powerful fertilizers. Fertilizing with urea alone will lead to smaller yields.
Let's say that average yield woud drop to 50% and that I would need not 53 bu 80 people's yearly urine. That would mean I would only provide enough corn for 120 people each year, for a input of 80, which gives a ratio of 3:2. Seems good enough. Unfortunately this is not the case.
Human urea is the result of human diet and metabolism, which gets nitrogen from many different protein sources. Self-sustainability means that those 120 people would have to eat only corn and meat from corn-fed livestock, or trade this for other protein sources (which would only externalize this unsustainability: some other people's diet would have to change). Even if it were possible to keep up with the same urea output without severe weight loss, this would not be enough:
- First of all, plants use nutrients to grow many inedible parts, and that is an important drain of nitrogen. This also means all plants, not just the ones we eat.
- Livestock would still need food sources other than corn. The above assumptions assume well-fed cattle.
Finally, as someone already noted in another comment, human urine contains a significant amount of salt, and without its removal this could lead to excess salinization that would render the soil infertile in the long term. And the higher concentrations of urea needed could also worsen the already present problem of eutrophication.
But using urine might still be a great help with local, temporary unavailability of better fertilizers.
... which you have to keep locked up, because terrorists. Usually they're smart enough to avoid hanging around in rusty white Ford Transits with Irish plates, but you'd probably not be too surprised to see the numbers on that.
I had some stuff stolen in the past, but never fertilizer.
[Separating urine from sewage could mitigate some environmental problems](https://news.ycombinator.com/item?id=30272019)
I do worry about a build up of salt over time since I live in a low precipitation climate (12”/year). The article doesn’t seem to touch on that concern.
> However, ammonia emissions, nitrogen leaching and nitrous oxide emissions per product unit were higher from organic systems.
Basically, chemical fertilizers are much more efficient and have more uniform distribution of nutrients.
[0]: https://www.sciencedirect.com/science/article/pii/S030147971...
Pratchett's character employs people to collect the "night water" - they get paid for collection, and the recycler gets paid after processing.
"Terry adds:
"And let me say right now that practically everything in the career of Harry King is fairly based on fact (except for the trolls)."
I know that farmers collect the sludge for I assume fertilizer.
If that stage could be modified to keep the nutrients that seems like the best thing going forward.
Synthetic textiles cause 35% of ocean microplastics[1] (ie the largest single source), so this is not a small waste stream.
[0] https://news.ycombinator.com/item?id=31520673
[1] https://portals.iucn.org/library/sites/library/files/documen...
Pee and poo get a lot smellier when mixed together, so an outhouse isn't a good proxy.
> To pasteurize the pee, it stays in the jug for at least two months before the farmer applies it
A 2 month "buffer" (beyond that needed due to crop seasonality) needs to hold a lot of pee.
This processing time can be reduced to 10 hours by adding watermelon seeds[1], which contain the enzyme urease.
If only the Romans had known this! They stored large amounts of urine (converting to ammonia) for washing clothes. For this reason, Roman laundries were legally forbidden from being located within city limits.
[0] https://news.ycombinator.com/item?id=31800128
[1] https://www.researchgate.net/publication/291165299_Citrullus...
This really should be added to the Guidelines. It might avert some future embarrassment for others.
I want to follow the rules. This was a discoverability failure (as your need to link to a third-party search tool as the "source" should demonstrate).
Thanks again.