There's a lot of info available online on the subject of human urine as fertiliser
This is a good introduction:
Aside from the associated water saving -- flushing less -- advantage, there is a scientific case that urine may be the answer to a looming global shortage of phosphorus, a key component in fertilisers.
- Aussie scientist calls for human urine fertiliser
- Our ancestors recycled their urine: why shouldn't we?
Despite the 'yuk' factor, human urine is actually a relatively clean substance. It should be sterile when produced at the body factory. Compared to other sources of manure fertiliser -- cow, horse, sheep, chicken -- it carries much less chance of contamination by pathogens.
Indeed, in-house human urine -- rather than the other solid stuff -- is where most of the good nutrients are at.
The downside is the smell. However, if urine is diluted and spread on soil or mulch within 24 hours of its production, the odour issue won't register significantly in the process. Although some commercial system do -- the preferred domestic management approach rule should be don't store your urine: use it fresh.
In situations of drought or water restrictions, recycling urine can save a significant amount of water. Even low-flow toilets use approx 6 litres per flush (as opposed to 13.2 litres for the full) so that a visit to pee on average 5 times per day will use up a daily quotient of 30 litres of water.
After working as a nurse for many years, especially in geriatric facilities, urine doesn't scare me at all. I also recall the time before sewerage connections were installed in houses and folk relied on outback 'can' toilets and under bed 'potties' -- just like kids' toilet training hardware-- to get them through the night without en suites.
I've been experimenting. So far so good. While it takes some dedication to collect and distribute human urine -- production is easy -- compared to other exotic gardening activities, like making manure teas and composting, it has its efficacy merits.
Why bother with pee, you ask?
I think the core advantage with urine harvesting is that it can contribute to your water budget by reducing usage. It won't impact on your water bill much given the way the utilities currently charge, but each week you could be saving 300 litres of drinkable water from being flushed away. Scandinavians are building townships that recycle urine as a form of sustainable sewerage management.
Is the effort worth it for the plants?
Hypothetically you'll save on input costs as you won't be importing fertilisers.Aside from the phosphorus advantage, research is very supportive:
- Urine: Closing the NPK Loop
- Scientific American: Gee Whiz: Human Urine Is Shown to Be an Effective Agricultural Fertilizer
- Modern Farmer:Can Human Urine Replace Chemical Fertilizers?
- Human Pee With Ash Is a Natural Fertilizer, Study Says
Indeed if you were feeling a bit low on any day and feeling a tad worthless as a human being , you can take heart from the fact that you could supply enough urine to fertilize roughly 6,300 tomato plants a year.
There's power in pee!