Serious question: Urine as a nitrogen source for organic composting

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For another thread, I looked up the use of urine in compost to replace nitrogen.
But I don't understand the chemistry of exactly how it all works as a compost activator and as a fertilizer. - http://www.soils.wisc.edu/extension/materials/ManagingUrea.pdf
Do you?
After reading all the references shown below, I'm still a bit confused about how urine acts as an organic compost aid.
Here's what I can figure out so far ...
It seems while undiluted urea has an NPK of roughly 46-0-0, human urine is already vastly diluted, with an NPK of about 12:1:2. Even so, human urine must still be further diluted something like 1:10 to be applied directly to growing plants because of the chance of something called 'burning' (or 1:20 in potted plants because of salt buildup in constricted containers).
But how does it work in a compost pile?
As far as I can tell, urease in the compost soil breaks the urea molecule (NH2)2CO first into ammonium carbonate (NH4)2CO3 and then into ammonium 2NH4 and carbon dioxide (CO2 gas) & finally into ammonia molecules (NH3 gas) and water.
My main problem is what to do to make sure the nitrogen remains in the compost soil and isn't vented to the atmosphere as a gas.
Since ammonia is highly miscible in water, forming NH3(aq), I assume if I keep the compost soil moist, that will hinder venting of the nitrogen as an ammonia gas. Lower winter temperatures should also keep the ammonia more in the soil than as a gas. Apparently I can raise the pH and the amount of organic matter, which should keep some of the ammonia in the compost.
Do you have any experience in this?
REFERENCES: - Urea: http://en.wikipedia.org/wiki/Urea - http://www.howtodothings.com/home-garden/how-to-use-urine-as-a- fertilizer - http://www.guardian.co.uk/lifeandstyle/gardening-blog/2009/nov/13/ composting-urine - http://barebonesgardening.blogspot.com/2007/10/free-urea-based- fertilizer.html - http://en.wikipedia.org/wiki/Compost#Urine - http://www1.agric.gov.ab.ca /$department/deptdocs.nsf/all/faq7758? opendocument - http://www.soils.wisc.edu/extension/materials/ManagingUrea.pdf
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On 1/15/2012 6:53 PM, Chuck Banshee wrote:

I'd also post in rec.gardens for someone there who knows more plant biochemistry than me, but the urea in urine is no different from urea used in fertilizer. Sometimes pure ammonia is injected into soil as fertilizer and as you point out, water will hold it there.
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On Sun, 15 Jan 2012 19:14:17 -0500, Frank wrote:

I switched the sci.chem to rec.gardens. Thanks for the advice.
Googling for a comparison paper of urea fertilizer and urine, I found this interesting paper from the Journal of Agricultural and Food Chemistry, 2007, 55, pages 8657-8663 titled: "Use of Human Urine Fertilizer in Cultivation of Cabbage - Impacts on Chemical, Microbial, and Flavor Quality".
Interestingly, as you intimated, they found that the urine was as good or better than the commercial stuff.
More interesting to the point, they recommended 'no more than 6 months' storage of the collected urine! I'm amazed as everything else I read said that the urine should be used within 24 hours because of ammonia (gas) formation.
I'm sure it works - but - I want to better understand the whole process so that the maximum nitrogen gets into the compost as usable nitrogen and not vented to the atmosphere as ammonia.
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On Mon, 16 Jan 2012 01:02:23 +0000, Chuck Banshee wrote:

I forgot to post the URL to the scientific paper: http://www.nku.edu/~longa/classes/calculus_resources/docs/cabbage.pdf
I find it suspect that they found the urine-fertilized cabbage tasted 'better', as I would have expected no differences between commercially fertilized and organically fertilized (i.e., urine-fertilized) cabbage.
Still - my question is HOW best to keep the nitrogen in the compost from turning into ammonia gases and simply venting away.
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Chuck Banshee wrote:

Interesting question. The conversion from urea, uric acid etc to ammonia is going to be done by some microbe. I think the risk is that if you make the environment unsuitable for that class of microbes it will be unsuitable for others that are more useful. Another possibility is to try to bind the ammonia so it isn't lost as a gas. Ammonium ions ought to bind to clay and humus colloids which have significant cation exchange capacity. Also cold composting, maintaining it damp and ensuring the pH isn't too high will all reduce the loss of ammonia to the air.
I think the widespread use of urine as fertiliser is limited by lack of a suitable collection mechanisms and the yuck factor. The latter is composed of the reaction to the smell and the belief that it is "dirty". The yuck factor is a big issue. People are often aghast at the idea of water derived from treated sewerage being used in the normal water reticulation system, despite evidence that the water would be as safe or safer than collected ground water.
The smell issue is commonly accepted as not a show stopper when using manures. Poultry manure or poultry bedding which contains large amounts of manure can produce a most revolting stench far worse than human urine but this doesn't stop them being used at least in agricultural settings. If I lived in a built-up area I would be restricted in using such fertilisers due to having regard for neighbours.
If you ask Mr or Ms Public is urine safe to use on the garden they will probably tell you that you can catch diseases from it. This isn't true in general. It may possibly be true if the donor has a urinary tract infection, such a person would very probably be aware of the illness and so should cease donating until they are well. In the absence of such an infection fresh urine in sterile. It could also become infected if stored in such a way that it became a growth medium for microbes that originated elsewhere. If you are adding it to your compost or even directly to the soil this is hardly likely to be an issue. As the article points out the few pathogens found cannot easily get into the cabbages. Bring up your kids to pee on the lemon tree!
As the price of oil (and so synthetic nitrogenous fertilisers) goes up we may find some creative person who can find a way to collect urine cheaply instead of sending it down our rivers and out to sea and then having to use power to fix atmospheric nitrogen in its place.
David
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If the ratio of brown to green additives to your compost pile is about 25/1, you pile won't smell as it will be in balance with the needs of the composting microorganisms. Then the urea will be bound in the proteins of the flora and fauna of the soil ecology, and will be released at a use able rate for the plants during the microorganisms' life/death cycles. To insure the minimum lost of nitrogen, cover its source with mulch that is kept damp, i.e. compost in situe.
--

Billy

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On Mon, 16 Jan 2012 10:43:58 -0500, Brooklyn1 wrote:

It's uncalled for to attack someone's unsubstantiated theory as 'dumb billgoat' as there may be a basis in fact to the original statement ...
However, in this thread, we're only looking for scientifically proven data for preventing the nitrogen in urea from gassing off as ammonia.
So, while I won't believe the 25:1 ratio above until/unless scientific evidence shows it to be be true, I 'can' believe what was implied in the following references: - http://extension.usu.edu/files/publications/publication/AG_283.pdf - http://www.nku.edu/~longa/classes/calculus_resources/docs/cabbage.pdf - http://www.soils.wisc.edu/extension/materials/ManagingUrea.pdf
Basically, these documents tell us from 50% to 90% of the nitrogen in urea is lost to the atmosphere (as ammonia) when urine is simply poured on top of the compost pile and left there.
The reason is that some of the urea [(NH2)2CO] is first turned to ammonium carbonate [(NH4)2CO3] and then into ammonium [2NH4] and gaseous carbon dioxide [(CO2 gas)] & finally into gaseous ammonia [(NH3] and water [H2O].
The goal is to force that nitrogen that would otherwise gas off, to recombine into compounds (nitrates?) that plants can use. I haven't figured out 'what' compounds these would be - so if you have papers on that, it would be useful to know.
So far, to minimize the nitrogen gassing, I will employ two techniques: - I'll maintain the moistness of the compost heap (by sprinkling water) - I'll cover the heap in clean soil (as I do anyway to deter vermin)
If anyone finds a BETTER way to forestall nitrogen evaporation in urea- enhanced composting, please cite how (references are always appreciated!).
And, if you know WHAT the process is that converts the nitrogen to useful compounds for the plants, I'd like to know also.
Thanks all!
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Urine has a fertilizer value of N/P/K 18:2:5. Wow!
Plant Physiology
Nitrogen assimilation and fixation
Availability of nitrogen to plants is often a limiting factor in growth and productivity • despite the fact that N2 is the most abundant gas in the atmosphere Nitrogen can exist in pools of different chemical forms, nitrogen cycle
• reduction of N2 to ammonia=nitrogen fixation (bacteria, lightning, industrial)
• ammonia is oxidized to nitrite, then nitrate=nitrification (by some bacteria)
• organics are converted to ammonia=ammonification (by bacteria & fungi)
• nitrate is reduced to N2, returned to the atmospherenitrification (bacteria) In taking up and utilizing nitrogen, plants incorporate it into carbon-nitrogen compounds Most plants take up nitrogen primarily in the form of nitrate (NO3-)
• except in conditions where nitrifying bacteria don't grow well (low pH, anaerobic)
• then ammonia (NH4+) will be available for uptake
• many forest species take up primarily NH4+, since forest soils are more acidic (less nitrification)
• NH4+ leaches less than NO3-, since NH4+ adheres to soil colloids NO3- is actively transported into and concentrated in the cells by a NO3- / H+ carrier (symporter) Assimilation: NO3- is reduced to nitrite (NO2-) by nitrate reductase using NADH • addition of NO3- induces the expression of nitrate reductase (regulated at transcription and enzyme activity)
• nitrate reductase has Mo, heme, and FAD cofactors (Mo deficiency can lead to N deficiency) NO2- is reduced to ammonium (NH4+) by nitrite reductase using ferredoxin (Fd)
• nitrite reductase has Fe-S and heme cofactors
• located in plastids NH4+ is incorporated into carbon compounds: amides (amino acids) and ureides Incorporation into amino acids is primarily by the GS-GOGAT pathway GS-GOGAT cycle 2 glutamate + 2 NH4+ + 2 ATP -> 2 glutamine + 2 ADP • enzyme is glutamine synthetase (GS) glutamine + alpha ketoglutarate + NAD(P)H -> 2 glutamate + NAD(P)+
• enzyme is glutamate synthase (GOGAT)
--

Billy

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On Mon, 16 Jan 2012 21:56:44 -0800, Billy wrote:

Now that's interesting!
Since it's compost we're working with, we don't know (yet) which plants will be using the nitrogen.
So, I guess, we want the nitrogen as both a nitrate (NO3-) and as an ammonia (NH4+).
I wonder how we know if a plant that we plan on fertilizing with this compost uses its nitrogen as nitrates versus ammonia?
And, depending if we want more nitrates versus more ammonia, I wonder what we'd need to do to tilt the chemical balance one way or the other?
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Chuck Banshee wrote:

I don't think it is feasible to manage the situation down to that level of detail in soil.
David
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David Hare-Scott wrote:

i thought we were talking about urine?

woodland, shrubs, perennials tend to like the latter (roots fed via fungal activity). garden veggie plants tend to like the former (yes there are always exceptions :) ). all the perennials around here are mulched and that is how they are fed. we don't fertilize them but they always bloom or grow well.

i say gardeners do it all the time.
look at how a forest functions, the pH is usually more acidic, the organic materials tend to layer on top (and not be mixed in). this favors fungal growth and nutrient cycling (more ammonia). so if you have a specific plant or garden that does better with the lower pH (blueberries) then manage the soil by layering organic materials on top and do not disturb the soil much at all otherwise. i'd use shredded bark, leaves, or pine needles (not exclusively pine needles).
to favor bacterial nutrient cycling adjust the pH to neutral to slightly alkaline, mix the organic materials into the soil (instead of layering them on top) if the soil is too light and sandy also take the opportunity to add some clay (encourages water retention, but also adds more anaerobic pores for nitrifying bacteria to colonize). planting legumes with the proper innoculants will also boost the nitrifying capacity of the soil (i much prefer this to adding fertilizers). at the end of the growing season, plant a cover crop (rye is a favorite) to soak up the extra nitrogen. cut it back in the spring and then plant.
songbird
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Feasible? No. Possible? Yes. Personally, I think that the degree of control that Chuck wants, can only be found in hydroponics, not organic gardening.
--

Billy

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On Wed, 18 Jan 2012 09:13:57 -0800, Billy wrote:

I'm not actually trying to 'control' so much as not to 'waste'.
For example, if I didn't know better, I'd just pour the urea on the top of the pile and leave it at that. But that would be a waste.
If I really wanted to control it, I'd 'inject' the urea ... but that's too much work for a single home sized compost heap.
I'm content with simply covering the urea with moist soil, since that seems to keep 90% of the nitrogen locked up instead of gassing out.
Like anything new ... it's a bunch of simple things that get us most of the way there. So, I'll do the simplest things that work best.
It's more about not wasting ... and not doing something stupid or counterproductive ... than about control.
Thanks for all the advice & viewpoints. I learned a lot!
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That being the case, I would apply the urea to the garden or pots and then water it in. If you don't till your soil the mycorrhiza will spread the the nutrients, including the nitrogen, around in the garden, and the life and death cycles of the microbes you encourage will feed the plants.
--

Billy

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As the article says, the reaction is driven by the pH; High pH --> NO3-, Low pH --> NH4+
In general, annuals like high pH, and perennials like low pH.
<http://en.wikipedia.org/wiki/Mycorrhiza> Another wrinkle that I haven't investigated much is mycorrhiza. A symbiotic (generally mutualistic, but occasionally weakly pathogenic) association between a fungus and the roots of a vascular plant.
--

You really don't need to worry about the NO3-/NH4+ ratios, because
healthy soils will feed your plants.
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Don't know if the ways to reduce N losses are "better" rather than just different.
Diluttion, watering in & cultivation are mentioned along with some chemical techniques.
http://wesnetindia.org/fileadmin/attachments/newsletters/august08/Urine_Harvesting.pdf
cheers Bob
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On Mon, 16 Jan 2012 22:25:34 -0800, DD_BobK wrote:

Urine_Harvesting.pdf
Nice one. Lots of good numbers to use as a reference point.
I liked the section on how to minimize nitrogen losses in stored & applied urine via non-ionized ammonia gassing.
"The urine mixture should be quickly incorporated into the soil, to minimize ammonia loss. The best method of doing this is by applying urine to farrows or holes, which have to be covered over immediately after application."
For storage, they suggested reducing the pH from 9 to 3 using a fertilizer-friendly acid (e.g., by adding 26 mmol of sulfuric acid (H2SO4) per liter of urine.
They said one study never lost more than 10% of the nitrogen (as non- ionized ammonia gas) during application - but that once applied and protected by a cover of soil, further nitrogen losses, they say, were "negligible".
And, their estimation of about 5 grams of nitrogen per liter of urine, and of 500 liters of urine (which is five pounds of nitrogen) and 50 liters of faeces per person per year may be useful overall, as a background metric. (They estimated a single person's urinary nitrogen/ phosphorous/potassium output was 2.4kg/0.3kg/1.1kg per year.)
In addition, I hadn't realized urine composting reduces carbon emissions, especially since it does release carbon dioxide as a gas, in addition to ammonia gas.
I also hadn't realized we excrete exactly the same amount of nutrients that we eat (I would have thought some was consumed somehow), and that the amount of NPK excreted in urine was roughly 90% for Nitrogen, and about 75% (roughly) for both phosphorous & potassium.
I'll add it to the reference list: - http://extension.usu.edu/files/publications/publication/AG_283.pdf - http://www.nku.edu/~longa/classes/calculus_resources/docs/cabbage.pdf - http://www.soils.wisc.edu/extension/materials/ManagingUrea.pdf - http://wesnetindia.org/fileadmin/attachments/newsletters/august08 / Urine_Harvesting.pdf
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Chuck Banshee wrote:

It is a peculiarly American obsession with balancing compost heaps though. You *really* have to work at it to get a compost heap not to behave correctly if you are adding a cubic metre or so of stuff at a time. The whole heap goes hot and rots down fast no matter what you put on. Woody thick stems do need mixing in with something nitrogen rich - but grass cuttings will do the job just as well as anything else.
A hot heap with a lot of grass cuttings on *will* smell of short chain fatty acids during the fast stage breakdown - slightly sweet stale BO smell for a few days. And one of mostly pine needles and trimmed conifer branches will smell of oil of wintergreen. You can get it to smouldering internally in a big heap. Provided that you don't crush the air out of it you can get fast composting this way with almost any mixture of materials added. You might at the start of a season need to feed it with a starter culture - particularly for a small garden.
If you manage to make it anaerobic wet and slimy then you will get a reducing environment and ammonia gas emitted, but otherwise the fungi and bacteria can pretty much look after themselves and turn your urea into bound ammonium salts. There will always be a slight smell during compsoting so you don't want the heaps too near the house!

The main one is make sure the heap stays suitably moist (not wet) and hot. This means a heap size and shape that is roughly cubic. Ammonia is very soluble and if there are short chain fatty acids around from the decomposition of other material it will be bound as ammonium salts.

In the early stages of composting any free ammonia should react with some of the otherwise volatile short chain fatty acids. Both will smell if they escape from the pile.

Not worth the effort of covering it with soil. The thin top layer tends to dry out and will need turning over but it gets burried next time you cut the grass anyway.

Oxidation to soluble nitrates and combining with short chain fatty acids as slightly more stable ammonium salts.
Regards, Martin Brown
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By obsession you mean an efficiently run compost pile? Yeah, we can be like that.

So you agree that a balance needs to be achieved between the brown (C), and the green (N) components of the pile; say a C/N ratio somewhere between 20 and 30.

Any citations on short chain fatty acids combining with ammonia in compost piles? In sheep rumens and colons, yeah, but compost piles? Citation please.

If the NH3 is floating away, how do you bring these reactants together, a hermetically sealed reaction chamber? Ammonia is converted in the atmosphere into N2O, a very strong greenhouse gas. As good stewards of the land, we should reduce our production of ammonia (better control of compost pile).

--

Billy

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Are you calling me un-american?
:)
I just pile stuff up and pull out what I can. Once in a while I'll run into a cigarette pack or plastic toy from the 1950s. Back in the pile it goes. You can never tell when the right bacteria might show up.
Turn the pile over, add water? You've got to be kidding. One of the nice things is that you can just let it lie there.
--
Dan Espen

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