Every day, gardeners across the world flush away a valuable and sustainable source of fertilizer for their plants -- urine. Urine is a good source of nitrogen and other minerals and, providing it is used correctly, is completely safe. Using urine as a fertilizer saves money, fossil fuels (used extensively in the production of chemical fertilizers) and water (no need to flush!). It's a standard of some organic gardens.
Using urine also cuts down on river pollution -- urine is a major source of nitrogen that contributes to river eutrophication if expensive denitrification is not used at the water treatment plant. And it's not a backwards step, it's space age technology -- NASA has used urine in hydroponics systems!
- Keep it separate. The golden rule with urine use is to keep it separate from other bodily wastes. Urine is clean and needs to be kept that way. Pee in a bottle, or invest in a urine-separating toilet.
- Use it fresh. We all know that stale urine smells. That's ammonia, and it's made from nitrogen. The smellier your collected urine, the less nutritious it will be for your plants, as well as being unpleasant to apply.
- Always dilute. Urine is too strong to be used neat on plants. Dilute at least 5:1, and it can be diluted up to 10:1 for use on tender plants and seedlings.
- Water at the roots. It's good practice when watering not too splash the leaves, but to water at the roots. This saves on evaporation, and dry leaves are much more resistant to disease.
- Spread it around. Urine can be salty, and using too much of it in one place can harm plants. Use it throughout your garden so no one area suffers from an overdose, and don't use it every time you water a plant.
- Feed hungry plants. The plants that will benefit most from urine fertilizer are the ones with the highest nitrogen requirements. Try it on leafy vegetables like cabbages and cauliflowers, corn, or anything that needs a quick pick-me-up.
- Other uses. Neat urine is too strong to be used directly on plants, but it can be used as a weedkiller; a few applications, especially if used on hot days, should finish off your weeds. It can also be used neat as a winter spray for fruit trees, to discourage fungal diseases.
- Activate! A final use for urine in the garden is as a compost activator. The nitrogen in urine will speed up the composting process and kick start a slumbering heap.