Use Human Urine to Make Fertilizer

Last Updated: July 31, 2022

Scientists in Finland have found that wood ash and human urine perform just as well as more expensive mineral fertilizers for red beets.

Wood ash and urine

The combination of your pee and burnt, carbon-rich wood ash is rich in nutrients, nitrogen, phosphorus, potassium, calcium, and magnesium! All just what the plant doctor ordered for your garden.

Why Should I Pee for Fertilizer?

Well, first off, in two separate studies done by Finnish scientists, the tomatoes and red beet plants treated with the mixture of urine and wood ash produced 4.2 times and almost 2.5 times more tomatoes and red beet respectively. Additionally, as part of the control experiment, commercial mineralized fertilizers were found to have produced similar amounts of food.

Secondly, it’s cheap. As long you’re an average healthy person with a reasonable diet consisting of a balanced ratio of vegetables, carbohydrates, fats, minerals, and proteins, your urine should be fine for the following ways of including yourself in your garden’s watering and nutrient cycle.

Thirdly, just like composting, once you’ve set up your urine fertilizer system and processes, you’ve already begun optimizing your self-reliance journey.

Fourth, it’s fast-acting. The nitrogen in your urine is almost immediately accessible by plants through the treated soil or in treated water.

“Urine from a single human individual could fertilize some 6,300 tomato plants, which could produce 2.41 tons of tomato fruits.”

Human Urine and Wood Ash as Plant Nutrients for Red Beet

How Do I Make a Wood Ash / Urine Fertilizer?

The first method of integrating a fresh supply of nitrogen via your urine starts with understanding a bit of the chemistry. Urine is high in salts and has to bond with leaves, cardboard, and other materials high in carbon to reach the optimal mixture for the fertilization of your plants. Once burnt, the bonding process is easier, faster, and more effective in mixing with your planting pots and soil.

Step 1. Collect your carbon: dry leaves, underbrush, wood scraps, and cardboard in a safe place to burn. Avoid using ash that’s been labeled, inked, or has any other type of material on it rather than that papery feeling.

Step 2. Burn safely and within proper areas. There’s a heat wave going on.

Burn Barrel

Step 3. Urinate into a jar that can be refilled as you normally work in your garden. Fresh urine is essentially sterile, while stored urine is not (the same goes for drinking in case you were wondering). Stored urine has almost no use at all unless it’s been heavily treated by industrial processes.

Step 4. After your ashes have cooled, pour the contents of the glass jar into the ashes at the center and stir carefully. Continue stirring until you have a similar consistency throughout your urine/ash mixture.

Bear in mind that one person can essentially fertilize 10.76 sq. ft per day (Scientific American, 2010). As a general measure of thumb (or pee), it’s a ratio of about 1:9 urine to ash.

Step 5. Shovel your ash into your planting soil. Mix thoroughly and plant away!

How Do I Make Urine-Treated Water?

For soil with good drainage that is crumbly and earthy-smelling. Also works well for container gardens.

Grab a reclaimed plastic container and take a pee.

Dilute it with eight to ten parts water, and apply it to the soil.

Work the urine into the soil or apply the urine-treated water under the top layer of soil would ensure that less nitrogen is lost due to conversion to ammonia gas. A direct pour is fine as well.

After applying your newly created fertilizer, water the plant.

Ur Urine and Gardening Tips

Tip 1: Dilute and Don’t Pollute | Urea is a very strong fertilizer. So, it needs to be diluted. The urea in urine is already diluted by about 95%, but it needs to be diluted by about 900% total to be safe for use as a natural fertilizer. If you have a cup of urine, add a gallon of water.

Tip 2: Don’t Apply To Edible Plant Parts for Peace of Mind | While it doesn’t make much of a difference if you’re regularly watering and rinsing your produce before usage, at the point your plants are producing fruit, they don’t need that much nitrogen-treated fertilizer anymore.

Tip 3: Direct Applications | There are also times when you can directly apply urine without dilution. For example, do this with your established plants bordering or framing your garden.

Possible Risks in Using Urine in the Garden

In general, urine poses very few health safety risks at all.

Transmissible Illness

There are a few illnesses that are known to be transmitted by urine. Only the first one on the list below is directly linked to transmission by urine coming into contact with soil.


Leptospirosis is an infection caused by bacteria that is transmitted by urine. The urine usually comes from animals and is transmitted to humans through contact with soil or contaminated water.

Livestock, pets, rodents, and other wild animals are the primary sources of transmission. However, humans also shed leptospira bacteria in urine if they are infected. So, if you are infected and use your urine in your soil, you might increase the volume of leptospira bacteria in your soil. Those bacteria can live in soil for weeks to months.

According to the CDC, there are between 100-150 cases (out of 327 million people) of leptospirosis in the US each year. About half of those occur in Puerto Rico. So, the actual risk of being infected with the disease is very low. But, it’s still something to think about relative to using urine in the garden.


Cytomegalovirus (CMV) infection is the most common disease that can potentially be transmitted by urine. Symptoms of CMV may be confused with mild flu or sometimes mono.


Urinary tract infections or UTIs are caused by bacterial infections from things like some forms of E. coli or Citrobacter (from hospital-caused UTIs). Most UTI-causing bacteria are already ubiquitous in nature, reside in our intestines, or are prolific in hospitals.


Medications designed to treat bacterial or fungal infections such as antibiotics or antifungals can also negatively impact the beneficial bacteria and fungi in your soil. Skip using urine that may inhibit the beneficial life in your soil.

Any bodily fluids from patients having chemotherapy or radiation are potentially dangerous. They can pose risks to septic tanks, caregivers, and more. So, keep this out of the garden.

Even drugs like sleeping pills and anti-depressants can pose environmental risks to wildlife. So it’s better to avoid using urine that may contain pharmaceutical residues in the garden for the safety of wildlife.

In Conclusion

If you’re looking for an economical way to increase the yield of your garden, and not have to buy mineralized fertilizer anymore, then integrating urine-based fertilizers in your garden and homestead is the way to go. As you work more on your crops and find ways to use both treated ash and diluted fertilizers, you’ll see the rewards of your processes in the wild growth of your plants.

In recognition of your growing self-sustainability in terms of cost and ingenuity, celebrate a little and relax on a chair in your garden, and watch the plants grow. You deserve it.

-Always-Be-Ready Max

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Resources and Links

Stored Human Urine Supplemented with Wood Ash as Fertilizer in Tomato Cultivation and Its Impacts on Fruit Yield and Quality

If case you’re wondering, Is It Safe to Drink Your Urine? Or, How to Purify Urine with a Solar Still

“Always Be Ready” Max

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