Some urine stuff

Ok, well, my yellow bucket has been sitting in my locker at school for about 5 weeks now. I have not been using it that much lately as I am quite busy and a bit disorganized these days. The bucket contains a mix of urine, of course, as well as saw dust and bokashi (selected microorganisms in wheat bran) and is topped with straight bokashi. Can you imagine how tat bucket smells right now? I bet you can’t because it actually does not have much smell at all. This is important since it is the smell that really detracts a lot of people from this idea. So having peed in plenty of straight sawdust and experienced the smell when left for too long, I can confidently say it is the bokashi that is making the difference. Especially since the bucket has a tight fitting lid which usually makes things smell even worse. But the bokashi thrives under anaerobic conditions, so the bucket is ideal.
I did a bit of pee research and came across the paper below (and others).  The researchers here (in Finland) used human urine to fertilize cabbage.  Here is a bit of their intro about human urine (are you as excited as i am?):

Human urine is a natural resource produced by every household. In human excreta, urine contains mostly nitrogen (N), phosphorus (P), and potassium (K) (1). Urine has a fertilizer value of N/P/K 18:2:5 (2), and for urine mixed with flush water, the ratio can be N/P/K/S 15:1:3:1 (3). Each individual produces 1–1.5 L of urine per day, the chemical composition of which depends on his/her feeding habits, the amount of drinking water consumed, physical activities, body size, and environmental factors (4). In general, pure human urine contains very few enteric microorganisms (5). The nutrient content present in human urine may mean it can be a good fertilizer for plants. This may be increasingly important in the future, with population growth and the corresponding increased demand for food and demand to save water and energy.
Urine is produced after filtration of the blood in the kidneys, and therefore, it contains low-molecular-weight compounds, since proteins are not filtered. About 75–90% of N is excreted as urea, the remainder being in the form of either ammonium or creatinine (6). Urea is rapidly degraded by urease to ammonium and water, which may elevate pH values up to a pH of 9; this can also reduce the bacterial population, although ammonia evaporation is also higher at higher pH values.

The urea/ammonium in urine and urea/ammonium in artificial fertilizers are similar; that is, 90–100% of urine N is in the form of either urea or ammonium, as has been verified in fertilizing experiments (7, 8). The P and K contents in urine are almost totally (95–100%) in an inorganic form (6). These ions are directly plant-available; for example, the phosphate plant availability from urine has been demonstrated to be as good as that of chemical phosphate (7). Urine has been successfully used to fertilize barley (8) and cucumbers (5). The growth and yields were as good as could be obtained with mineral fertilization.

So this project has some promise after all.  I will be using some of my sawdust and bokashi urine at my community garden plot which I hope to incorporate this weekend.  I won’t be doing a control (space too small) but I’ll still be curious to see the results.

But human urine is not necessarily perfect.  From another paper’s abstract:

Stored human urine had pH values of 8.9 and was composed of eight main ionic species (> 0.1 meq L–1), the cations Na, K, NH4, Ca and the anions, Cl, SO4, PO4 and HCO3. Nitrogen was mainly (> 90%) present as ammoniacal N, with ammonium bicarbonate being the dominant compound. Urea and urate decomposed during storage. Heavy metal concentrations in urine samples were low compared with other organic fertilizers, but copper, mercury, nickel and zinc were 10–500 times higher in urine than in precipitation and surface waters. In a pot experiment with15N labelled human urine, higher gaseous losses and lower crop uptake (barley) of urine N than of labelled ammonium nitrate were found. Phosphorus present in urine was utilized at a higher rate than soluble phosphate, showing that urine P is at least as available to crops as soluble P fertilizers.

So phosphorus seems to be the best benefit from human urine.  But the N is important also since it is so mobile in the soil (due to it’s negative charge) and very important to plant growth.  It would be interesting to see how things change after being mixed with sawdust and bokashi.  Both are high C materials but the biological activity of the bokashi may have an effect on the nutrients in some way.


3 thoughts on “Some urine stuff

  1. Brilliant. Thanks for this. My two kids and I have moved into a van and have been composting our waste ever since. I’ve been feeling kinda weird about it because like you say no one wants to talk about it and I get really weird looks when I do. My bokashi group thinks I’m nuts.
    Really glad to know I’m not. Your amazing. Keep up the great work.

  2. Excellent article Chris – you sure do a way of looking at problems from different angles – i am looking forward to watching as you develop solutions that will impact so many – thank you – peace for all

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