Urine is an excellent natural fertilizer and among the very oldest ways to create fertile soil. After all, pee plays quite a crucial role in the earth’s nitrogen cycle.
Mammals (including us), birds, reptiles, amphibians, insects, and fish contribute nitrogen via urine to cycle back through the environment. Protein-rich foods – like legumes, eggs, dairy, and nuts – are plentiful in amino acids, and these are converted into urea within the body. Every time we urinate, urea – a rich source of nitrogen – is released back into the soil or water, giving plants the nutrients they need to grow.
It’s a wonderful closed-loop system. Plants require large amounts of nitrogen to grow; we eat the plants (or the animals that consumed the plants), we pee, plants grow, and the cycle continues.
If you can get past the ick factor of urine, it’s truly one of the most sustainable and earth-friendly ways to supply nutrients to your edible crops and ornamental gardens.
Urine: The Original Fertilizer
If you don’t already know it, there’s several ways to make good use of your pee in the garden. And we gardeners are nothing if not resourceful!
As a nutrient solution for plants, urine is the original organic fertilizer. Our pee is mostly made up of water, between 91 to 96%, has a slightly acidic pH of roughly 6.2, and is basically sterile when it leaves the body. The rest of urine is made up of nitrogen, phosphorus, potassium, sulfate, sodium, magnesium, chloride, and calcium – seven of the 17 essential plant nutrients. Sitting right there, in your bladder.
After water, the next largest components of urine are nitrogen (in the form of urea), phosphorus, and potassium. Although it can vary widely based on diet, pee typically has an NPK value of 11 – 1 – 2.5.
When diluted and applied to the soil around roots, these macronutrients are nearly 100% available to plants for immediate uptake.
Plants love it. You don’t need to take my word for it – several field studies have been conducted on urine as a fertilizer for cabbage, beans, cucumbers, beets, and tomatoes. Each study reported great success, with urine performing equally well – if not better – than synthetic fertilizers.
It’s sustainable. Everybody pees and they do it every single day. We produce, on average, about 1.5 quarts of urine daily. Urine is about as plentiful, renewable, and local as a resource gets.
It’s free. Need I say more?
Is it Safe to Wee in the Garden?
In healthy people with a balanced diet, it’s absolutely safe to use pee to feed your crops – just as nature intended. Urine is virtually sterile when it leaves the body. While it does house bacteria, pee doesn’t normally contain pathogens.
Unless you’re currently fighting a bladder or urinary tract infection. Then you’ll want to hold off on using your urine until the condition has completely cleared up.
For added peace of mind, you can:
- Age urine for 6 months. No microorganisms can survive in pee that turns into ammonia. (More on this below).
- Apply it to the soil. Target urine fertilizers around the root zone and avoid wetting the leaves and fruits.
- Wait a month. After applying it, wait a month before eating raw crops like lettuce.
But – what if you’re on medication?
The short answer is no – you shouldn’t apply urine anywhere in the garden if you’re taking medication.
Pharmaceutical residues are excreted through urine, which can disrupt the soil microbiome and get taken up by plants. Some classes of drugs persist in the environment or are extremely resistant to breaking down, and can potentially accumulate in the soil over time from repeat applications.
Antibiotics, antifungals, chemotherapy and radiation drugs, antidepressants, sleeping pills, and hormonal treatments (including birth control) are some of the types of medications that can leach into soil and water systems. When used on edible crops, pharmaceuticals have harmful effects on wildlife by entering the food chain.
But don’t fret if you can’t use pee outdoors – urine is but one of many incredible liquid fertilizers that you can make for free.
Making Your Own Urine Fertilizer in 3 Easy Steps
The process from pee to fertilizer is quick, cheap, and easy.
1. Collect it
Round up an assortment of glass jars or any other pee-catching receptacles you’re comfortable using.
As a bit of a glass jar hoarder, I’ve got plenty of old pasta sauce and pickle jars on hand. The larger ones with a wide mouth make the act of wee-catching a bit easier for those of us working with lady bits.
Whenever you can, save jars that have measurements etched in the glass. This is super handy and will save you a step.
If your jars aren’t marked, take a measuring cup and fill it up with water. Then pour the water into your jar, and mark the water line.
You’ll need to know your fluid ounce measurements for diluting urine later on.
Once you have your jars and measurement lines sorted, you can set to the task of saving pee.
There are two schools of thought on when to use urine fertilizers – fresh or aged.
After a day or so outside the body, the urea in urine will begin to convert into ammonia. Stored and sealed up tightly, urine aged for 6 months becomes inhospitable to life and is utterly sterile. While it’s still an effective nitrogen-rich fertilizer, aged pee will also be eye-wateringly pungent.
Fresh pee, on the other hand, is stored for no more than 24 hours before use. It has virtually no odor. And because it’s used up within a day, you won’t need to keep a large collection of pee jars lying around.
So in this pee collector’s opinion, fresh is best.
Start by catching the first whizz of the day, then collect your urine for the next several hours with the plan to fertilize plants in the evening.
Or you could always catch and release urine on the go, diluting smaller amounts of it at a time and applying it to the garden right away.
Between deposits, you can stow the jars, with tightly screwed lids, in a cool and dark place to keep pee fresher for longer.
2. Dilute it
Whether used fresh or aged, pure urine is much too strong to be applied directly to soil. It needs to be diluted first.
The commonly-accepted dilution rate for fertilizer is 1 part urine to 8 to 20 parts water. However, you can experiment with different ratios. Bolder gardeners swear by a more concentrated 1:3 or 1:5 solution.
When it comes to quick-acting fertilizer like fresh pee, it’s always easier to add more than take away. It’s wise to start with weaker solutions and work your way up to more concentrated urine ratios. Just bear in mind that young plants and seedlings are sensitive to salts in pee and should always be given urine in milder doses.
Urine Math
To calculate your dilution, tally up your urine fluid totals and pour it all into a 5 gallon bucket. Then add 8 to 20 times water.
Alternatively, you can mix your pee fertilizer directly into your watering can by working backward from the capacity of your container. To calculate the amount of pee to add, simply divide the total volume of the container in ounces by 8 to 20 plus 1. Like so:
(Total container volume ÷ dilution ratio + 1 = the amount of pee to use).
To achieve a 1:8 ratio in a 2 gallon watering can, for example, I divided 256 ounces by 9 to get 33 ounces of pee to add. To simplify things, I rounded it down to 32 ounces.
Diluting urine directly into the watering can means we can avoid having to transfer it here later – no need to bail it out or siphon it from a bucket.
Then all you’ve got to do is fill it the rest of the way up with water.
3. Apply it
As soon as it’s diluted, water your pee fertilizer into the garden. Apply it as close as you can around the base of plants, targeting the root zones.
Urine is terrific for booster feedings throughout the growing season. Heavy feeders like tomatoes, sweet corn, squash, melons, cucumbers, peppers, and potatoes will greatly benefit from monthly urine fertilizer applications.
And that’s all there is to it. It’s easy and it’s free and it’s always close at hand. The more you use your pee in the garden, the less off-putting working with it becomes.
Because when you see urine for what it actually is – a waste product that’s chock full of essential nutrients – it really seems all the more silly to be flushing it down the drain.
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