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

  • Marijn Zandee
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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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  • 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.

Microbiologist & emergency WASH specialist
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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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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

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

Dear Ralf
Dear all,
I do not agree to the statement that ammonia in urine ideally should be transformed to organic nitrogen.

The grounds for my statement are:
1) The only way I know of transforming ammonia to organic nitrogen goes via bacteria. These use organics as their source of energy. But the bacteria do not only multiply, increasing the bacterial mass. They also have to respire. Thus, it is less than half of the energy of the organics fed to the bacteria that ends up in the bacterial mass, which is the mass containing the organic nitrogen. More than half will be lost in endogenic respiration. From a sustainability and greenhouse gas point of view, it would be far better to use the feed organics either for biogas production, if the feed organics are easily degraded like food waste, or to use it as biofuel for incineration, if it is woody waste. To use this energy just to build ammonia nitrogen into organic form is a waste which does not use the potential of the energy in the organics to decrease the greenhouse gas emissions.

2) In composts, often large proportions of the input nitrogen is lost, largely as ammonia, but also as nitrous oxide (N2O) and, in the best of worlds, as nitrogen gas. The nitrogen losses are especially large when composting substrates with lots of easily available nitrogen, and especially if the nitrogen is in the form of ammonia. E.g. in the paper "Nitrogen loss during composting of poultry litter" Venglovsky et al. (2011) report that 65% of the initial N was lost when poulty litter was composted and in "Nitrogen turnover and loss during storage of slurry and composting of solid manure under typical Vietnamese farming conditions" Tran et al. (2010)report that the losses were 45-55% when the pig slurry was composted with straw.

3) The nitrogen that ends up as organic nitrogen in composts has on average a very low efficiency in feeding the plants and thus in replacing mineral (chemical) nitrogen fertilizers. In a literature review by Odlare et al. (2000) they found that of the nitrogen in the compost, the literature indicates that on average about 0-15% is used by the crop the first year, another 5-10% the next year and in total over sevaral years about 20-30% of the organic nitrogen in the compost is utilized by the crops. One important reason for this percentage not being higher is that a lot of the organic nitrogen is mineralized when there is no crop on the soil to take it up. See the next bullet, no 4.

4) Organic nitrogen in the soil has a big drawback in that is is not directly available to the plants. It only becomes available after it has been mineralized and mineralization is not well syncronized with the need of the plants.
For mineralization, the soil moisture and temperature has to be suitable. In temperate climate like Sweden and Denmark, and I think also northern Germany our winter crops (winter wheat, winter barley, winter rape, etc.) need a very large part of their nitrogen very early in the year, when they start to grow in the spring. In mid Sweden, they need ample access to mineral nitrogen from about mid April. At this time the soil temperature is only just over freezing, which means that organic nitrogen is not being mineralized in the soil. By end of June, when the winter crops stops to take up nitrogen as they start to ripe, the soil temperature has increased to 15-20 degrees centigrades and thus then there is a lot of mineralization and this continues through the autumn. This in turn means that lots of nitrogen is mineralized at times when there are now crops that can take it up. Thus, a large part of the nitrogen that is mineralized in the late summer and autumn is lost in the winter and spring, causing eutrophication of e.g. the Baltic Sea.

5) Source separated urine has a unique and very valuable property in that it is readily plant available (see e.g. "Practical Guidance on the Use of Urine in Crop Production" at www.ecosanres.org/publications.htm ). This means that it can be used to supply winter crops with the nitrogen when they need it and thus increase their health, competitiveness against weeds, and quantity and quality of their yeild. As it has such a high plant availability it can be supplied to the crop just before it is needed, thus minimizing the risk for losses and negative effects on the environement.

This is the reason why several of the large urine diversion projects in Sweden during the 90-ies were initialized by organic farmers. The farmers realized the unique quality of the source separated urine and they wanted it for improving the competitiveness of their crops against weeds and for better yields. Source separated human urine was, just as the manure from animals, allowed as fertilizers in organic farming in Sweden before we joined the EU, just as it still is by IFOAM, International Federation of Organic Agriculture Movements. It is a great pity that it is not allowed in organic farming by the EU.

I really think that the sustainability of a urine diversion system is decreased if the urine is used for composting instead of for fertilizing directly, because by composting only some 15% of the initial nitrogen will end up being used by the plant (50% left after composting and of this 30% is used by plants). The rest is lost to the environment causing large negative environmental effects (N2O, NO3, NH3).

If the urine instead is used directly as a fertilizer it can replace mineral fertilizers at a rate of 1:1, thus DECREASING the global warming caused by its production in the form of emissions of N2O and CO2.

I am open for any discussion of my conclusions, if this discussion is based on data from scientific publications.

With sincere wishes for increased sustainability,
Håkan
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  • Marijn Zandee
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Re: Use excreta compost only for non-edible plants (preferably)?

Dear Hakan,

Thank you for this contribution. Could you give a more complete reference for Odlare et al., 2000 ?

rgds

Marijn

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

Dear Hakan,
dear Ralf,
dear all,

important discussion. The last comments of Hakan and Ralf touch on questions about organic fertilizing in general. Far away from the topic: use excreta compost only for non-edible plants. Elisabeth should create a new topic. WG 3 - Renewable energies and climate change - should become invited to participate.

IFOAM regulation does not distinguish between human feces and urine. Today are human excrements prohibited for use on crops for human consumption. New IFOAM Standard will allow more in accordance to COROS assessment reference.

IFOAM Basic Standards (2005) still valid May 2012:
4.4.4 Manures containing human excrement (feces and urine) are prohibited for use on crops for human consumption.
Exceptions may be made where detailed sanitation requirements are established by the standard-setting organization to prevent the transmission of pests, parasites and infectious agents and to ensure that manures are not mixed with other household or industrial wastes that may contain prohibited substances.

New Standard under developement, actuall Draft 0.3 will be in discussion until June 2012. Draft version 0.4 will be the version submitted for a final approval vote. Regulation concerning human excrement since Draft Version 0.2:
4.4.5 Human excrement shall be handled in a way that reduces risk of pathogens and parasites and shall not be applied within six months of the harvest of annual crops for human consumption with edible portions in contact with the soil.

Draft History

IFOAM Standard Draft 0.1 (Version 2010)
4.4.5 Manures containing human excrement must not be applied on soil that will be used to grow crops for human consumption within the next six months.
Regional or other exception at certification body discretion
Exceptions may be made where detailed sanitation requirements prevent the transmission of pests, parasites and infectious agents and manures are not mixed with other household or industrial wastes that may contain prohibited substances.
4.4.6 Manures containing human excrement (feces and urine) are prohibited for use on crops for human consumption

IFOAM Standard Draft 0.3 (May 2012)
4.4.5 Human excrement shall be handled in a way that reduces risk of pathogens and parasites and shall not be applied within six months of the harvest of annual crops for human consumption with edible portions in contact with the soil.
4.4.6 Mineral fertilizers shall only be used in a program addressing long-term fertility needs together with other techniques such as organic matter additions, green manures, crop rotations and nitrogen fixation by plants. Their use shall be justified by appropriate soil and leaf analysis or diagnosed by an independent expert.

COROS, GOMA

COROS, Common Objectives and Requirements of Organic Standards (International reference to perform bi-lateral or multi-lateral equivalence assessments of organic standards)
Objective:
Sheet DATA ENTRY, 4.3.5 :
Organic soil fertility management does not use of human excrement on crops for human consumption without measures to protect humans from pathogens.

COROS Consultation Discussion:
Objective:
Organic soil fertility management does not use of human excrement on crops for human consumption without measures to protect humans from pathogens.
FiBL (Otto Schmid): nothing is said on soil tillage, which is a key criticism on organic farming: We might add: this includes the emphasis on soil conservation and minimum tillage practices.
GOMA-IFOAM answer (GOMA, Global Organic Market Access, a joint initiative of FAO, IFOAM and UNCTAD):
Rate of tillage is not commonly addressed in organic standards (which is why it is criticized) and therefore would seem out of place in a document that presents the common requirements. This document, an equivalence instrument, is not intended to lead standards in a new direction but to reflect the current status of organic standards.

More about Lisbon Treaty and how to change organic regulation in europe now: www.ifoam.org/about_ifoam/around_world/e...er_2012_EN_heavy.pdf

COROS, GOMA and humanure, one example:
GOMA ( www.goma-organic.org ), the Global Market Access project, is a joint initiative of FAO, IFOAM and UNCTAD.
GOMA organized a draft working group for co-operation on Organic Labelling and Trade for Asia and decided to develop Asia Regional Organic Standard (AROS). WG meeting: 26-27 September 2011, Seoul,
"Human Waste: It was noted by the standards developer that COROS and AROS currently have the same wording and also that two countries, Philippines and China, specifically allow it in their standards with restrictions. Discussion included adding more detailed language in the restrictions, the need to allow this substance due to the peaking and eventual decline of phosphorous sources, and whether there should be different language regarding of urine. It was decided to define and treat urine and solid human waste the same, and add some more explicit restrictions requiring further treatment, examples being composting and fermentation."
( www.goma-organic.org/wp-content/uploads/...MA_Asia_WG_Seoul.pdf )

Regards,
Gerhard

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

Dear Marijn,
The complete reference for Odlare et al., 2000 is:
M. Odlare, M. Pell, P.-E. Persson. 2000. Kompostanvändning i jordbruket : en internationell utblick (In Swedish). RVF utveckling, [1103-4092]; 2000:6. Svenska renhållningsverksföreningen. Malmö, Sweden.
This report is however not available on the net, as the organisation has changed name since the report was printed.

If you want the report, you can probably get it from Monica Odlare att Mälardalen University or from me at Swedish University of Agricultural Sciences.
Best regards,
Håkan
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  • HakanJonsson
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Re: Use excreta compost only for non-edible plants (preferably)?

Dear Gerhard,
Thanks for a detailed and good description of the IFOAM regulations and thanks for correcting me. I was wrong in writing that human excreta is allowed by the IFOAM. After studying the regulations better, I should have worded it "use of human excreta are prohibited by IFOAM, but standard-setting organizations may make exemptions provided that detailed sanitation requirements preventing the spreading of pests, parasites and infectious agenst are established." I guess that it was this exemption that the Swedish organic branding organisation KRAV used for many years and I think that it is a real pity that, due to the present EU regulation, they are not allowed to use it any more.

Detailed sanitation requirement have been published by the WHO in their guidelines on "Safe use of wastewater, excreta and greywater" volume 4 "Excreta and greywater use in agriculture"

They generally recommend that a Hygien Risk Assessment should be made for the systems, but they also give the detailed sanitation requirements which I have upload with a file. From these it is:
1) obvious that source separeted urine poses a very small risk.
2) considering that some crops, also food crops, has a long growing period and many others, like sorghum, millet, rice etc are cooked before eating, actually many crops can according to "Practical guidance on the use of urine in crop production" www.ecosanres.org/pdf_files/ESR2010-1-Pr...InCropProduction.pdf , pages 24-28 be fertilized also with urine which has not been stored, which otherwise is the recommended treatment for sanitization. BUT NATURALLY FOR CROPS EATEN RAW AND WHICH MIGHT COME INTO CONTACT WITH THE URINE OR THE URINE FERTILIZED SOIL, THE URINE SHOULD BE STORED at least FOR 6 MONTHS AT 20 DEG C before fertilization.

For faeces, the FAO guidelines give several options. For three years, while I had a UDDT in my house, I used the option of composting for at least a week at more than 50 deg C. I have a well insulted food waste compost. By feeding and turning it I got the temperature up to 50 deg C. When confirmed that I had at least 50 deg C, I added the faeces in the center of the compost. The faeces got a temperature of 55-60 deg C within a day. I waited about 5 days and then I turned it, but still keeping it in the center of the compost. This I consider a very safe sanitization.

However, as Ralph points out, it is a bit tricky to reach 50 deg C in small composts. It takes good insulation, experience and taking good care of the compost. Thus, I generally recommend the storage option given by WHO. In Sweden this means to store the faeces for two years, and then you can compost them a low temperature. After this they are a nice looking and very good fertilizer.

I really hope that IFOAM will allow excreta or at least urine as a fertilizer not only as an exemption but as a general rule. One important reason for doing this is that source separated human urine is by far the fertilizer around with the lowest cadmium (Cd) level. It has a cadmium level of just about 0.6 mg Cd/kg P, which is extremely low.

One company sells fertilizers declared low in Cd in Sweden. They are guaranteed to have less than 12 mg Cd/kg P. The average level in Europe is about 80-85 mg Cd/kg P. Manure from both conventional and organic farms in Sweden have Cd levels of 7-18 mg Cd/kg P.

EFSA (European Food Safety Authority) in their scientific opinion on cadmium in food www.efsa.europa.eu/en/efsajournal/pub/980.htm states that "The mean exposure for adults across Europe is close to, or slightly exceeding, the TWI of 2.5 µg/kg b.w. Subgroups such as vegetarians, children, smokers and people living in highly contaminated areas may exceed the TWI (Tolerable Weekly Intake) by about 2-fold. Although the risk for adverse effects on kidney function at an individual level at dietary exposures across Europe is very low, the CONTAM Panel concluded that the current exposure to Cd at the population level should be reduced."

The fact is that you can not find any fertilizer, organic or conventional, that is even close to urine when it comes to being low in Cd. Thus, my conclusion from this is that urine should be recommended as a fertilizer for food crops, out of health and sustainability reasons! I hope that IFOAM will find this also.

Sustainable regards,
Håkan
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  • gerhard_dario
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Re: Use excreta compost only for non-edible plants (preferably)?

Dear Hakan,
dear all,

Urine is low in Cd. Costs to eliminate toxic Cd are estimated up to 100 €/MT. Vegetarians are highly exposed to Cd. Phosphate containing high levels of Cd will become sold as cheaper fertilizers for poor countries. More expensive Cd-"clean" phosphate rock will be used in high developed nations. Additional problems are gypsum at the retrieval of phosphate from the rock and natural radioactivity.
EC Commission decision of January 2006 allows Sweden to set lower limitations of Cd content in fertilizers (100 grams / metric ton eq 0.1 mg / kg)
( eur-lex.europa.eu/LexUriServ/LexUriServ....129:0019:0024:en:PDF ). But EU is only responsible to regulate mineral fertilizers (chemicals). Regulations concerning organic fertilizers are national law, not community law. National, regional and EU government regulations supersede EU Organic Standards and may vary from member state to member state.
I believe that wording of IFOAM standards next year will be: "Human excrement shall be handled in a way that reduces risk of pathogens and parasites and shall not be applied within six months of the harvest of annual crops for human consumption with edible portions in contact with the soil."
But eg. German "Düngemittelverordnung" (fertilizer regulation) must also be changed to allow application in Germany.
I am IFOAM affiliated and will ask IFOAM Head Office, EU-Group and FIBL to check the correctness of my remarks.

Regards,
Gerhard Pelzer

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