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Biochar From Human Waste Could Solve Global Fertilizer Shortages, Study Finds (theguardian.com)

(Monday August 11, 2025 @05:50PM (msmash) from the how-about-that dept.)


Biochar produced from solid human excrement could [1]supply up to 7% of global phosphorus fertilizer needs annually , according to a Cornell University study [2]published in PNAS . When combined with nutrients extracted from urine, the process could provide 15% of phosphorus, 17% of nitrogen, and 25% of potassium used in agriculture worldwide.

The biochar production process reduces solid waste volume and weight by up to 90%, while allowing nutrient proportions to be adjusted for specific crop requirements.



[1] https://www.theguardian.com/science/2025/aug/11/biochar-from-human-waste-could-solve-global-fertiliser-shortages-study-finds

[2] https://www.pnas.org/cgi/doi/10.1073/pnas.2503668122


So, you're saying it's made from hot shit? (Score:2)

by Powercntrl ( 458442 )

I think they might owe some royalties to [1]Nelly. [youtu.be]

[1] https://youtu.be/zDUYXlev5CI

Interesting (Score:3)

by GoTeam ( 5042081 )

They claim their process can filter out pharmaceuticals and micro plastics. If that's true and not prohibitively expensive ($ or electricity), maybe they can be successful.

Re: (Score:1)

by Ziabatsu ( 1270854 )

I have suspicions that their "Filtering process" is "Burn it and let someone else breath it"

Pharmaceuticals and plastics aren't the problem (Score:2)

by rsilvergun ( 571051 )

Especially the plastics because those are everywhere.

The problem is various pathogens. So it's not really usable in the food supply. You can use it on lawns after some treatment but that's about it.

You could possibly treat it to deal with the pathogens but the problem with that is the same problem we always have which is that the treatment is expensive so you either have a product that can't compete or somebody starts cutting corners on the treatments and people start getting sick.

Re: (Score:2)

by Sique ( 173459 )

Every pathogen there was has been charred to charcoal once the stuff has been processed. By the way - fertilizing with manure is as old as agriculture, even without any processing.

Re: (Score:2)

by HBI ( 10338492 )

Raw sewage is the fertilizer of choice in Korea. Apparently there is a Korean farmer's almanac that says the right day, and they all go out and burn the rice paddies, toss the shit on them and then fill with water.

The smell is like nothing else I have ever experienced. I kept being over there for that day in the early spring, year after year.

One of the harvesting methodologies is via porta-potties. In the US they'd fill them with that blue chemical substance to kill the smell. But in Korea, the feces and

Re: (Score:2)

by markdavis ( 642305 )

> "The problem is various pathogens. So it's not really usable in the food supply. You can use it on lawns after some treatment but that's about it."

Biochar is free of live pathogens because it is charcoal. It is designed for food-crop usage. That is the point of biochar, that it removes the risk compared to trying to use "treated sewerage sludge" that does contain microplastics, heavy metals, Pfas forever chemicals, pathogens, and pharmaceuticals (all of which the biochar process destroys).

> "that th

Re: (Score:3)

by markdavis ( 642305 )

> "(all of which the biochar process destroys)."

Reply to self. I don't think it would destroy heavy metals, though.

One step closer... (Score:3)

by johnnys ( 592333 )

... to Soylent Green.

Re: (Score:2)

by rsilvergun ( 571051 )

Bold of you to assume that the ruling class is going to allow us to have Soylent Green instead of just blowing us all the kingdom come with drones if we get too uppity.

I knew this would eventually happen (Score:2)

by sinkskinkshrieks ( 6952954 )

Recycling the brown and the yellow separately as resources. Just so long as Bill Gates doesn't comparison taste-test.

Our sewage system is not designed for this (Score:2)

by Pinky's Brain ( 1158667 )

Sewage systems are on of the greatest advances of society, unfortunately it has made recovery of good quality humanure impossible. It's all polluted, by a little, but a little adds up when you cycle things.

Viable? (Score:2)

by walkerp1 ( 523460 )

I'm always excited by the practical application of science, so I gave this some thought. In my estimation, the biggest impediment to this process is going to be the heavy metal concentration. It might be possible to use the resultant fertilizer for non-food crop use like forestation or biofuel production, but it becomes a problem if you ever want to convert those regions since the metals will mainly remain in the soil.

Another issue is that collecting human urine prior to wastewater dilution isn't really

Why no animal waste (Score:2)

by Misagon ( 1135 )

Ridiculous amounts of animal waste is not taken care of, and let to rot and produce greenhouse gases.

I'd think that would be low-hanging fruit to take care of first.

Echoes of Milorganite (Score:2)

by divide overflow ( 599608 )

Milorganite, a brand of biosolids fertilizer produced by treating sewage sludge by the Milwaukee Metropolitan Sewerage District, is another well-established fertilizer product introduced in 1926 and sold in many garden centers. It has had the same issues as the biochar product discussed in this topic, including issues with heavy metals concentration as well as synthetic organic compounds, radionuclides, and many known carcinogens.

<dark> eat Depends: cook | eat-out.
But eat-out is non-free so that's out.
And cook Recommends: clean-pans.
-- Seen on #Debian