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Fertiliser qualities of excreta products from UDDTs compared to vermicompost digester
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- joeturner
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Re: Fertiliser qualities of excreta products from UDDTs compared to vermicompost digester
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from this book: books.google.co.uk/books?id=ONYZm_J0gr8C...#v=onepage&q&f=false
" The water and nutrient holding capacity of clay soils is higher than that of sandy and silty soils, therefore leaching of NO3, P, other nutrients and organo-chlorines is dependent on soil texture. Conversely the risk of accumulation of harmful components in the root zone following repeated application of large doses of manure is higher in heavier textured soils than in light soils. Clay soils become more easily waterlogged after heavy rainfall because of a lower hydraulic conductivity, i.e. the possible rate of water transport through the soil. Under waterlogged conditions, denitrification can occur and harmful N2O may be formed. Under extreme acid or alkaline conditions (pH<4 or>9), soils tend to deflocculate, the structure is destroyed and leaching of many organic and inorganic components becomes inevitable. Volatilization of NH3 from soils with higher pH values is greater than from those with lower pH values."
From this FAO document: www.fao.org/wairdocs/lead/x6113e/x6113e05.htm
"Toilet compost (TC) and human urine are among natural fertilizers, which raise interest due to their double advantages to combine sanitation and nutrient recovery. However, combination of urine and TC is not so spread probably because the best ratio (urine/TC) is still an issue and urine effect on soil chemical properties remains poorly documented. This study aims to determine the best ratio of urine and TC in okra cultivation, by targeting higher fertilization effect combined with lower impact on soil chemical properties. Based on Nitrogen requirement of okra, seven treatments were compared: (T0) no fertilizer, (T1) chemical fertilizer (NPK: 14-23-14), (T2) 100% urine, (T3) 100% TC, (T4) ratio of 75% urine + 25% TC, (T5) 50% urine + 50% TC and (T6) 25% urine + 75% TC. Results indicated that T4 (75% urine + 25% TC) gave the highest plant height and yield. In contrast, T2 (100% urine) gave the lowest results among all treatments, indicating toxicity effects on plant growth and associated final yield. Such toxicity is confirmed by soil chemical properties at T2 with soil acidification and significant increase in soil salinity. In contrast, application of urine together with TC mitigates soil acidification and salinity, highlighting the efficiency of urine and TC combination on soil chemical properties. However, further investigation is necessary to refine better urine/TC ratio for okra production."
from this research paper www.tandfonline.com/doi/abs/10.1080/09593330.2014.984774
Urine application has a different effect on different soils in different places. This is just a fact, not "over thinking".
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In response to this comment:
Yes, I know that some here have had good results with their urine irrigation schemes, but these must be unusual situations and should not be seen to apply to everyone else in all situations. That's clearly not the case, otherwise there would be no need to have agronomists and soil scientists advising farmers on the correct amounts of fertilizer to use on their crops.
Urine fertilization has to a large extend happened in a developing world setting. The problem you describe of soils with N (or P) levels that are already so high that additional nutrients do not help plant growth does -in my experience- not apply in those cases. The nutrient saturated soil problem is one associated with intensive livestock keeping. Where so much dung is spread on the land that it is over fertilized. This is probably why most trials with urine fertilization have worked well.
In general I think your comments on urine fertilization in this thread are valid. However, I think, you are "over thinking" things for practical purposes in the developing world.
Best
Marijn
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Regarding biochar from sanitation, this does happen (at close to full scale pilots), see for example:
forum.susana.org/forum/categories/224-th...nitation-and-hygiene
As I understand bsoutherland's post, he is not pyrolyzing the fecal sludge from the toilet, but crop residues. The biochar from this is then used as a sort of "nutrient sponge" for the urine collected in a diversion toilet.
Regards
Marijn
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Re: Fertiliser qualities of excreta products from UDDTs compared to vermicompost digester
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There are various designs for "rocket" stoves which char wood. In brief, rocket stoves are lit in a pipe which is embedded in an cabinet full of insulated material to ensure an efficient burn. If the insulation material is replaced with wood and holes are provided to allow gases to be released (which are then burned), the wood is charred.
en.wikipedia.org/wiki/Rocket_stove
If instead the insulation chamber was a collection vessel from a latrine, it ought to be possible to char faecal waste.
There may well be issues with the wetness of the material, smoke and gases - have you been able to overcome these, bsoutherland?
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Re: Fertiliser qualities of excreta products from UDDTs compared to vermicompost digester
While the start up fire is burning inside of the flue, moisture from the heated biomass is vented from the retort through a small pipe. When the moisture is exhausted and volatile gases begin to exit the small pipe, it is capped. Thereafter all volatile pyrolysis gases are forced through the series of small holes into the internal flue where they ignite to intensely heat and pyrolyze the biomass charge.
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Re: Fertiliser qualities of excreta products from UDDTs compared to vermicompost digester
Can You post some more information about your biochar methods?
Harry
Tasmania
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Re: Fertiliser qualities of excreta products from UDDTs compared to vermicompost digester
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cheers
Dean
Vermifilter.com
www.vermifilter.com
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Re: Fertiliser qualities of excreta products from UDDTs compared to vermicompost digester
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goeco wrote: Fact is that urine is not a balanced fertiliser. What I am trying to raise is that vermicomposting adds nutrients to the liquid effluent. By drying feces, UDDT systems make "active" biomass (a good carbon and nutrient source once decomposed), plus urine. There is a disconnect because urine is not a balanced fertiliser. In contrast, vermicomposting digesters should produce a NPK-balanced nutrient-rich effluent. The issue I have is that this has apparently not yet been quantified by published research.
What I am trying to explain is that a vermicomposting digester produces "stabilised" humus (a good soil amendment rich in carbon) that apparently has low levels of pathogens (again not quantified) and the bulk of fecal material is reduced to liquid which combines with urine to be a nutrient-balanced liquid fertiliser (with variable pathogen levels depending on what happens next). There are two options for the liquid, secondary treatment and surface drippers, or simply discharging directly to underground soakage trenches that feed suitable food crops like bananas that respond to water + balanced nutrients.
Mmm. This relates to another term we should be using when discussing amending things to soils - the idea of "nutrient availability". It is complicated chemistry, but basically it means that there are different forms of NPK, some of which can be taken up by the plants and some of which cannot. Part of the problem with urine is that urea is immediately available, so if the crop is not actually needing the nitrogen right now, it can easily be lost altogether from the soil. So composting (and also processes like vermicomposting) help by changing the availability of the nutrients. It sounds counter-intuitive, but these actually sometimes make the nutrients less available, so more of them are stored in the soil rather than being lost as I described above. So a farmer might find that the compost does not have a rapid effect on this season's crop as you might see with a bag of fertiliser, but there is a long term improvement in the fertility of the soil so in the long term the crop growth is improved.
So this is the difference between a mix of fresh urine and faeces and a compost (or vermicompost) - the material has been "stabilised". The organisms have also changed the physical structure of the material to make it more suitable for use in the soil.
Even if the balance of NPK in the urine is exactly what is needed by the crop, a lot of the nitrogen will be lost during storage and application, and if it isn't applied at exactly the right moment may have little effect on the crop growth. Of course this depends again on exactly what the situation is.
In contrast the nutrients in the compost have been stabilised, so there are fewer losses during application and the timing is less critical because of the long-term release of the nutrients.
By recycling balanced nutrients to crops, the risk of growth-limiting factors (especially lack of P) is reduced. One thing that needs to be clear is that by increasing productivity of land using liquid only ('booster'), organic matter (biomass or 'soil amender') levels are increased and so improve soil quality by being returned to the soil. Production of biomass is mostly limited by two factors, availability of water, and nutrient shortage. Abundance of some nutrients and shortage of others is no better than shortage of all nutrients.
cheers
Dean
That's correct, although we should be careful in suggesting that compost will solve all nutrient deficiencies in crops and the soil. Again, without knowing what those deficiencies are, we'd be operating in the dark. That said, because the nutrient availability in the stabilised compost/vermicompost has been changed, there is likely to be less of a problem with excess nutrients in the soil from compost than you'd get with an oversupply of urine or a commercial fertiliser. It's very difficult to add too much compost!
On the pathogen point, the best research I've seen suggests that worms alone not able to reduce pathogens to safe levels, in contrast to composting where the high temperatures kill them off.
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Re: Composting system by Human Endeavors (USA and in future Costa Rica)
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muench wrote:
Urine is a complete fertiliser and rich in P. In fact, it is usually valued especially for the P content (as well as the K and the micronutrients; more so than for the N). Also when compared to a commercial liquid fertiliser, don't forget that those cost money whereas urine is in theory for free (although yes, you may have to transport it which incurs costs as it's more diluted than commercial fertiliser).
I'm sorry but this is quite wrong and misleading, Elizabeth.
Plants require the correct amounts of various macronutrients (that's the NPK that we're discussing above) as well as a range of micronutrients to grow properly. Mostly they get these supplied to them from the soil. When the soil does not have enough of one or more of the nutrients, the plants will not grow very well.
Urine is a good source of urea, which is a good source of nitrogen. However, it is in no sense a "complete" fertiliser as it does not have equivalent levels of P and K, never mind the micronutrients.
But even if it did that's irrelevant as different plants in different soils need different amounts of NPK. In some situations the soil already has high levels of N, so adding more in urine is going to make no difference at all.
This idea that one can add anything to a farmed field and this will magically be what the soil and plant need is quite wrong.
Yes, I know that some here have had good results with their urine irrigation schemes, but these must be unusual situations and should not be seen to apply to everyone else in all situations. That's clearly not the case, otherwise there would be no need to have agronomists and soil scientists advising farmers on the correct amounts of fertiliser to use on their crops.
I agree with Dean that applying faeces will help in several respects, both in terms of adding other macronutrients and with adding organic matter to the soil. But even here the overall amounts of NPK may still not be what is needed by the crop and still may not be enough to replace all fertilisers - it entirely depends on the soil and the crop.
This whole subject is extremely complicated and site specific!
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- Levels of protein in the diet (doesn't matter whether vegetable or meat). A high protein diet results in high levels of N.
- Amount of water consumed by the individual. This affects dilution of nutrients in the urine (absolute levels), but does not affect the balance of nutrients (relative levels).
What I am trying to explain is that a vermicomposting digester produces "stabilised" humus (a good soil amendment rich in carbon) that apparently has low levels of pathogens (again not quantified) and the bulk of fecal material is reduced to liquid which combines with urine to be a nutrient-balanced liquid fertiliser (with variable pathogen levels depending on what happens next). There are two options for the liquid, secondary treatment and surface drippers, or simply discharging directly to underground soakage trenches that feed suitable food crops like bananas that respond to water + balanced nutrients.
By recycling balanced nutrients to crops, the risk of growth-limiting factors (especially lack of P) is reduced. One thing that needs to be clear is that by increasing productivity of land using liquid only ('booster'), organic matter (biomass or 'soil amender') levels are increased and so improve soil quality by being returned to the soil. Production of biomass is mostly limited by two factors, availability of water, and nutrient shortage. Abundance of some nutrients and shortage of others is no better than shortage of all nutrients.
cheers
Dean
Vermifilter.com
www.vermifilter.com
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- worked in sanitation for most of my life. taught plumbing. have plumbing and builders license, certified inspector in all facets of construction, PhD in public administration & have taught construction management in university, traveled numerous countries, Interest UDDT and sanitation & clean water
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Re: Fertiliser qualities of excreta products from UDDTs compared to vermicompost digester
The urine will have only minor affect on micro nutrients. Healthy micro nutrients comes from healthy soil. This is achieved by using the human fertilizer tilled into the soil. Commercial fertilizers kill the micro nutrients. Thought the feces is not as rich in nutrients it does contain about 10% of the N and K as well as 50% of the P. The feces (human fertilizer) also acts as a soil conditioner resulting in high humus, works, moisture retention, and micro organisms that produce micro-nutrients.
A person produces almost as much human fertilizer as is required to grow the food that will sustain him. This is one of the reasons that I am so positive on the UDDT.
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