Hi Elisabeth,

I think that's what I understood from your powerpoint but may not have accurately communicated that in what I wrote. Joe and I had a different view about the amount of P and K in the urine - or, rather, how that related to the balance which plants need. Some of the difference between Joe's view and mine may have been to do with availability in the soil. I have not had time to go into this in more detail.

To a large extent my view on the fertiliser value of urine is based on work done at the Centre for Alternative Technology (www.cat.org.uk/).

Thanks for letting me know that the powerpoint has been superseded.

Best wishes, Andy Warren

Hi Andy,
Sorry but you misread that information from my powerpoint file.
It said there:

Urine contains 88% of excreted N, 67% of excreted P and 73% of excreted K; the remainder is in the faeces

So in other words: The nitrogen that humans excrete is split over urine and faeces unevenly: most of the excreted nitrogen (or 88%) is in the urine. The rest, 12% of excreted nitrogen, is in the faeces.

I am assuming you were referring to this presentation that I did in about 2006: "Course 1 Unit 2 Characteristics of urine, faeces and greywater". I found a link to it by Googling: www.humanitarianresponse.info/sites/www....d%20grey%20water.ppt

I am also attaching it to this post but it's an old one and was done for an online course. I am sure it's been updated since then by the lecturer who continued with that online course (Mariska Ronteltap), so I am not recommending using it anymore.

Regards,
Elisabeth

P.S. I am going to move this post and the previous few out of this thread so that the thread stays more on topic.

"Urine has a fertilizer value of N/P/K 18:2:5"

From here:
pubs.acs.org/doi/full/10.1021/jf0717891#

I don't know where Elizabeth got her figures from, but they (or your interpretation of them) are wildly different to anything I've ever read. Given that NPK amounts are usually expressed as a ratio, I'm not even sure what a percentage could mean.

If you want to discuss any of your other points, including the soil science of British allotments, I'm happy to do so on a different thread.

A quick response to Joe Turner’s post on 11 August 19. I do realise that in straying into the area of ‘piss’ and its nutrient value I have gone rather off-piste. However, I will give some short answers, after which I’ll desist, at least in the context of this thread.

I understand urine is typically 88% N; 67% P; and 73% K. I got those figures from: Characteristics of urine, Faeces and Grey Water by Elisabeth Muench. That’s not such a bad balance. If I ‘normalise’ those numbers by treating the N as 100% then the P and K are respectively 76% and 83%. Dilution of urine (say 10:1 water to urine) is important mainly to avoid high levels of Sodium and Chlorine ions.

A NatSol client involved in certified organic production asked the Soil Association (SA) if they could use urine as a fertiliser. The answer was 'no' and I’m sure that two of the reasons were reasons that I have given, i.e. the risk of faecal contmanination and the fact that it does not add humus (unless composted of course). However, you are probably right, Joe, in saying that oestrogen isn’t a problem in soils, only in watercourses.

Given the concern that the SA has about the risk of faecal contamination (e.g. in urine separating pedestals) there could be some good reasons for handling male and female urine separately. In NatSol toilets the male urine almost all goes down a urinal and although this usually combines with female urine from the pedestal it would be a very simple matter to keep it separate. That would keep it free of faecal contamination.

To clarify: oestrogen in urine causes problems in water. I don't think it is believed it causes problems in soil.

AndyWarren wrote:
Are we missing something here? Most nutrients are in the urine. I’m sure that on some of the sites for which NatSol has supplied CTs the allotment association has planted soft fruit bushes over the urine soakaway in order to make use of this nutrient rich liquid, once known as household fertiliser.

Well, urine is certainly high in urea - which is a good source of nitrogen. The trouble is that it isn't correspondingly balanced in Potassium and Phosphate, so is unlikely to meet the needs of many crops on its own. Faeces is much more balanced in terms of NP and K.

Hence most many farmers spread farmyard manure (a mix of bedding straw, faeces and urine) rather than neat urine.

I highly doubt that most British allotments are limited by nitrogen.

I do know that the Soil Association does not permit the use of urine for probably three reasons: 1. although generally regarded as sterile it may not be, especially (though not exclusively) because it may suffer contamination from faecal material in the urine separation system, 2. it does not add humus to the soil, 3. it can contain medications, including oestrogen from the contraceptive pill. Having said all that, it’s a damn sight safer than badly composted (non 3F) compost made from faeces.

This is quite a tangent to the discussion, but I doubt that the Soil Association (which is one of the group's promoting 'organic' food - also known as 'ecological' food in other countries) was/is worried about any of those things. But let's talk about that on a different thread, it has nothing much to do with this.

This reminds me of the book ‘Future Fertility’ by John Beeby (1995) in which John makes the point that we are not short of nutrients from organic sources for growing food because there are a whole stack of these in urine, but we do need to find enough in the way of carbon sources to produce humus through composting the urine and carbon together.

Finding sufficient carbon sources for efficient composting and to achieve high temperatures is often a major problem. The other part of the quote does not really make a lot of sense.

The volume of well composted material from faeces is remarkably small - in comparison to the starting volume. I have noticed that in NatSol toilet vaults the volume roughly halves over a one year period in the UK climate and if left longer (and kept moist enough) it will probably halve again in the next two years. And it doesn’t stop there.

Yes. Faeces in toilet vaults often reduces in volume. That doesn't mean it is composting, of course.

Probably the best urine to collect is male, partly because it is free of oestrogen, particularly because it can be collected by a urinal and is therefore not subject to faecal contamination.

I highly doubt this is true. Given that the vast majority of farmed ruminent manure and urine is from females, and the majority of that is spread on fields, I suspect any problems with oestrogen would have been noticed.

But then men often don’t want to walk any distance to pee in a urinal on a remote site, they just pee where they are! Maybe they would make the effort if the nutrient value was made clearer.

I honestly don't know what this means. You have allotment toilets where the urine soaks away, some of which may be used by fruit trees. Are you seriously trying to suggest that it would be sensible to separate urine from men and women?

I’ve been enjoying this discussion (forum.susana.org/241-composting-toilets-...ng-toilet-a-misnomer)* about what the word composting might mean and about the quality of the finished product. I can see the importance of refining the definitions of compost and perhaps there needs to be a new definition for compost which is fit for growing food. It would need to easily remembered, have some kind of official status and become widely recognised and used. Of course, compost of that standard could be arrived at through different technologies and so the definition should not refer to the method used but rather to the standard reached. I am almost certainly not the person to be coming up with a new definition but somebody probably can. (FFF Compost - Fit for Food; 3F Compost * ? !)

Many of NatSol’s toilets go on allotment sites in the UK and our instructions make it clear that the compost should not be used for growing crops on those sites even if composting is continued for several years after removal from the toilet vaults. I feel reasonably assured that people understand that, and in the UK there is neither a shortage of food (yet) nor a shortage of other sources of compost to assist in the growing of vegetables. Consequently, the pressure to use whatever is available is almost certainly low. In poorer countries without access to garden centres or stables for horse muck, and where food may be short then the pressure to use compost from toilets (whether properly degraded or not) may be high.

Are we missing something here? Most nutrients are in the urine. I’m sure that on some of the sites for which NatSol has supplied CTs the allotment association has planted soft fruit bushes over the urine soakaway in order to make use of this nutrient rich liquid, once known as household fertiliser. I do know that the Soil Association does not permit the use of urine for probably three reasons: 1. although generally regarded as sterile it may not be, especially (though not exclusively) because it may suffer contamination from faecal material in the urine separation system, 2. it does not add humus to the soil, 3. it can contain medications, including oestrogen from the contraceptive pill. Having said all that, it’s a damn sight safer than badly composted (non 3F) compost made from faeces.

This reminds me of the book ‘Future Fertility’ by John Beeby (1995) in which John makes the point that we are not short of nutrients from organic sources for growing food because there are a whole stack of these in urine, but we do need to find enough in the way of carbon sources to produce humus through composting the urine and carbon together.

The volume of well composted material from faeces is remarkably small - in comparison to the starting volume. I have noticed that in NatSol toilet vaults the volume roughly halves over a one year period in the UK climate and if left longer (and kept moist enough) it will probably halve again in the next two years. And it doesn’t stop there.

Probably the best urine to collect is male, partly because it is free of oestrogen, particularly because it can be collected by a urinal and is therefore not subject to faecal contamination. But then men often don’t want to walk any distance to pee in a urinal on a remote site, they just pee where they are! Maybe they would make the effort if the nutrient value was made clearer.

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* Note by moderator: This post used to be in this thread about composting toilets and their name: forum.susana.org/241-composting-toilets-...ng-toilet-a-misnomer