Use excreta compost only for non-edible plants (preferably)?

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  • Marijn Zandee
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Re: Use excreta compost only for non-edible plants (preferably)?

Dear Ralph,

Thanks again for your answer, these are all subjects that I work very closely on at the moment, so the information here is important for me. I do agree that humic substances are very important, mainly for long term soil health and fertility.

As I wrote earlier, at the moment my feeling is that a mix of compost (preferably including high lignen material such as corn stalks or wood) and direct urine application would create a healthy soil, with some additional short term fertilization from the ammonium and nitrate from the urine.
One of the reasons for this strategy in is that one needs very large amounts of compost to cover the nitrogen, potassium and phosphate needs of a crop. With a combined approach we can create a living soil, while using compost a bit more sparingly (which is important for the people I work with).

I would like, once more, to invite other subscribers to the forum to add their views to this topic.

One more technical question:
Does anyone have any data on how fast Nitrogen from compost (the organic part, so not the NH4 and NO3) becomes available to plants. In other words, if I make a calculation of the Nitrogen needs of a plant can I substitute the grams N from urea or other fertilizer for grams N from compost, or does the organic N in compost become available much slower?

Thank you

Marijn
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  • Otterpohl
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Re: Use excreta compost only for non-edible plants (preferably)?

Dear Merijn,

The main thing is to convert mineral nitrogen like the ammonia in urine into organic forms ideally humic acids. Works well with combining woody waste - if dry they can absorb and evaporate excess of moisture. In addition this leads to much compost compared to teh frustration of the shrinking organic mass without woodbase.

In German: 'Holz macht Boden stolz' meaning 'wood makes soil proud' as an old saying among farmers.

Ralf

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Re: Use excreta compost only for non-edible plants (preferably)?

Dear all,

I also have a reservation about the "only using for growing food consumed within the household" rules (also regarding urine). I practice this is pretty much impossible to enforce. Especially vegetables tend to ripen all around the same time, so for example people have too many cucumbers and barter them for some rice or corn. As Ralph indicates above, for faecal waste the risks are bigger then for urine, because there are many more pathogens in faeces including some more severe ones than in urine.

Ralph, regarding your comment on using urine as a mineral fertilizer.
I would always advocate using compost (non human waste based) together with urine. To promote the living soil concept. As I believe that is a more efficient process than co-composting the urine, in terms of: nutrients preserved, simplicity, labor and input requirements for farmers. So I agree that using only urine is as bad for soils as using only synthetic fertilizers, but I would think that a compost and urine strategy is as good as your co-composting technique. Any thoughts on that anyone?

rgds

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  • Otterpohl
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Re: Use excreta compost only for non-edible plants (preferably)?

Rural toilet systems where the owners want to reuse their excreta should preferably be UD in order to reuse the big amount ot nutrients with very low hyginic risc. We do prefer composting of urine with woody waste to make good soil conditioner as we follow organic agriculture. Direct application of mainly mineral fertilizer is no healthy way of plant nutrition. Kitchen waste and yard clippings would be added here.

Faecal matter will hardly ever be composted in a safe way with above 70 °C on site so this should clearly be non-food for a long period of time. amounts are very small anyway. 'Their own pathogens' is not applicable as the wife may not wish to get sick through her husband or to contaminate visitors. There is a lot of nasty stuff that can survive in faecal matter.

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  • JKMakowka
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Re: Use excreta compost only for non-edible plants (preferably)?

Interesting discussion... just a quick remark from my side (I think that has not been mentioned yet; Edit: Gerhard Pelzer already mentioned it to some extend and it was also mentioned in the first post; but well for the sake off stressing this fact I will leave this post here):

Coming from a water-supply background: there has been an discussion in how far the recontamination of drinking water at the household level is a problem or not. And while you can usually measure an increase in coliform contamination at this level one has to keep in mind that illnesses do not spread this way, in contrast to a contamination at the water source or in a distribution network. Additionally one can expect that the inhabitants already have an acquired immune response to those pathogens that are present in the direct surroundings of their HH (note that this does NOT really help the children below 5 those immune system is still mostly untrained).

To some extent this line of reasoning can be applied to reuse of faecal material as fertilizer too; e.g. as long as the faecal material used is only "their own", and the food produced is only used for their own consumption (and not sold on the market for example), you will not spread illnesses and the negative health-effect will be relatively low.

Obviously this is not really the optimal solution, but I think this is something to keep in mind too.

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Re: Use excreta compost only for non-edible plants (preferably)?

Dear Christian,

Thanks for posting this.
I was asked by SOIL to closely read their publication: "The soil guide to ecological sanitation", now also in the Susana library, to come up with suggestions for further editions.

The compost in this video has been treated at their central composting plant. The method they have created for composting faeces at a reasonably big scale, to me seems the most advanced I have ever read about. In their publication they claim the following (which I am willing to believe):

1. They build their piles in such a way that the edges, which may not get warm enough for sterilization, do not contain faeces.

2. They monitor the temperatures of the piles and measure daily in a number of locations, to guarantee that all the material stays over 50 degrees Celcius, for 2 months. This system is based on literature: (Cairncross et al., 1993) which states that faecal matter will be safe after composting at 50 deg C, after 1 week.

To the best of my knowledge they have not yet been able to test the compost in a microbial lab, I have suggested them to do this at the earliest possible time, to verify their sterilization process. Maybe one of the SOIL people is a member here and can tell us what the word is on that?

Anyway, in short:

I think, based on the description of the system that the risks associated with their composting system are very small, especially compared to household scale treatment systems.

The safety of their compost should however be validated by lab analyses (preferably as an ongoing effort for each batch). If that has not happened yet.

Further, many of the issues raised earlier in this thread are of a cultural nature, apparently the people SOIL works with have overcome those.

Last, I would also suggest that compost from faeces should only be used on (fruit)trees, unless a secondary treatment, that is verified by lab analyses, has been used.

rgds

Marijn
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  • christian.rieck
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Re: Use excreta compost only for non-edible plants (preferably)?

Dear all,
very interesting discussion. I find the statement of Lucas very logical and convincing. There needs to be a sound and healthy middle way for use of excreta as it is a precious resource and at the same time poses health risks. It would certainly be the easiest way to restrict the use of excreta as proposed to only non-edible plants or at most fruit trees. Since the human factor will always lead to the mentioned carelessness of standards to a certain extent there needs to be clear and simple rules to follow. Looking at WHO rules it is mind-boggling and too complex to understand. In this sense the simple message of BD-farming (Steiner) not to use human excreta in agriculture is easy to remember and easy to follow. On the other hand such a rule might be too strict and steal the potential benefits for farmers. So where is the middle way - could SuSanA community try to come up with a recommondation of simple and most beneficial rules for use of excreta in terms of minimising health risk and taping the benefit of reuse?

As this fits to this topic so well, let me share with you the video of Soil on the agricultural activities with human excreta. The most critical part (around 6:45) is when people and even children apply the composted excreta with their bare hands on the soil. They use it for all kinds of vegetables etc...how would you guys appraise this practice?



Cheers
Christian
GIZ Uganda
Enhanced Water Security and Sanitation (ENWASS)
Sanitation for Millions
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  • lucasdengel
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Re: Use excreta compost only for non-edible plants (preferably)?

Dear Ralf and all,

I am a physician (Dr. med.) by qualification and half of my 58 years of life I have been living in Tamil Nadu, India. I had hepatitis A, amoebiasis, giardiasis (many times), ascariasis (roundworm), various diarrhoeas etc. yet I think that most of the offical standards (international, national) are overdone i.e. based rather on fear and on the concept of surgical hygiene (where hygiene = absence of all microorganisms) than on an understanding of soil microbiology, microbiological metabolism and ecology of soils etc. (I do not claim that I understand.)
The damage (in regard to the environment and to public hygiene) that is being done by mankind to itself is not due to low standards, but due to ignorance and carelessness about them, also carelessness at criminal levels.
I am also promoting biodynamic (BD) farming and respect the particular qualities and strengths of this type of farming, but I cannot accept the in-principle banning of human waste recycling into soils from the scenario of (certified) organic farming or of BD farming in particular. Organic farming argues with the risk of pathogens and pharmaceutical residues, but not dealing with the "shit" does not end it to exist. BD farming (Steiner) argues with the lack of life force (prana), and, as Ralf mentions, other fringe sciences argue with the information imprinted into water and possibly other biological saps and substances. (If the science of info imprints is on the right track, imprints can also be undone, corrected, "reprinted".)
All this is to simply state that we seem to need some more serious research in this field to arrive at a healthy middle way between "risk" elimination at ppt levels and over-confidently heroic messing around with our own excreta. I am not afraid, we seem to be on the right track.
Rgds, Lucas
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Re: Use excreta compost only for non-edible plants (preferably)?

Dear Ralph,

Thanks for the link to the article, I have not had time to really read it but it looks very interesting.

To the whole comunity,

A further question that hopefully someone can answer.

In many texts on Twinpit / Sulabh toilets, there is a claim that after 2 or 3 years of storage of the excreta in the pit that is not in use the remaining compost is pathogen free, apart from worm helminths. Does anyone have a link to a (recent) paper that either supports or refutes this?

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Marijn
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  • Otterpohl
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Re: Use excreta compost only for non-edible plants (preferably)?

Dear Marijn!

Example reference to Endocytosis of plants (it is an amazing topic! uptake of living bacteria though roots). If the community is wide awake we must change our practice. Legislation does not consider this pathway:

Turning the Table: Plants Consume Microbes as a Source of Nutrients
Chanyarat Paungfoo-Lonhienne1*, Doris Rentsch2, Silke Robatzek3, Richard I. Webb4, Evgeny Sagulenko5, Torgny Näsholm6, Susanne Schmidt1#, Thierry G. A. Lonhienne1#
1 School of Biological Sciences, The University of Queensland, Brisbane, Queensland, Australia, 2 Institute of Plant Sciences, University of Bern, Bern, Switzerland, 3 The Sainsbury Laboratory, Norwich Research Park, Norwich, United Kingdom, 4 Centre for Microscopy and Microanalysis, The University of Queensland, Brisbane, Queensland, Australia, 5 School of Biochemistry and Molecular Biosciences, The University of Queensland, Brisbane, Queensland, Australia, 6 Department of Forest Ecology and Management, Swedish University of Agricultural Sciences, Umeå, Sweden

Citation: Paungfoo-Lonhienne C, Rentsch D, Robatzek S, Webb RI, Sagulenko E, et al. (2010) Turning the Table: Plants Consume Microbes as a Source of Nutrients. PLoS ONE 5(7): e11915. doi:10.1371/journal.pone.0011915
Received: June 7, 2010; Accepted: July 7, 2010; Published: July 30, 2010

Kind regards

Ralf

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  • Otterpohl
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Re: Use excreta compost only for non-edible plants (preferably)?

Dear Geoffrey,
Dear All,

As you know most people will reject eating food from excreta compost. If food for others is produced, this must be respected. Few people would reject if this is 10 years old compost.

In addition we have lots of nasty pharmaceutcal residues and hormones from the pill. Over 10 years even those many absolutely non-biodegradeable ones will have been washed out.

Another aspect: all the composting is stil not relly really save for all pathogens at all times of operation. 10 years is short and jsut another saftey measure. Plenty of non-food-applications.

Another point: generally accepted scintific knowledge is just a fraction of what is going on in the universe, actually very crude and somewhat mediaeval. Quantum physics do apply to life. Entanglement means that there can be links of substances that have been attached somewhere. There is plenty of proof that also frequencies of substances can be imprinted on water. As crazy as this may sound, I personally do not want such links to other people. Such thinking is familiar to millions of people and there are traces of this in old cultural knowledge, too. E.g. this is part of the thinking behind Biodynamic Farming (they would say 7 years, I am more in the metric system). I would have called the authors crazy if i had seen this statement 30 years back : )

For all those resons: plant staff on your composted excreta if you eat this yourself or people who know and accept. Do not misuse trust of people who would not like it or even hate it. This is one of the resons we work on composting all excreta including urine with sufficient woody waste and some charcoal from woodgas stoves.

Kind regards

Ralf
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Re: Use excreta compost only for non-edible plants (preferably)?

Dear all,

First of all, thanks Elizabeth for broadening the discussion by transferring it to this forum too.

I think a lot of Ralf Otterpohls (and other comments) out of the ecosanres posts are very valuable, it would especially be interesting to hear more about the endocytosis path way (Can Martina Winker help us here?). For me they also echo a discussion we had here end of last year, this was the "reuse of faecal matter, is it worth it?" discussion thread, that ran into 4 pages and contains a lot of very useful info.

Elizabeth, would it be possible to have one of your colleagues go through that tread again and compile the key information and then add it to this discussion?

As I recall, the threat mentioned above also came to the conclusion that we need more stringent rules on how to post-process and/or use faecal waste. For the time being, I would agree with most comments made here to apply faecal waste only to non-food crops. Considering the small volumes this should not be a problem and could encourage tree planting.

I have probably said this before, but I think further research into how to safely use faecal waste and also how to handle waste streams from DEWATS systems, should be a priority for Ecosan research.

Kind regards

Marijn
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