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Does Human Urine Kill Grass? - Thankyourlawn

Does Human Urine Kill Grass?

Maybe you’ve seen your neighbor’s dog peeing on your lawn. Maybe you’ve been at a lawn party and couldn’t hold it. Or maybe you saw cow manure packaged as fertilizer and wondered if you could do it yourself. Regardless of why you’re reading this, we are here to answer your question: “is it good to pee on your lawn?”

There is a lot of conflicting data around whether human urine can make plants grow better or if it’s safe. Some sites say that human urine kills grass. Others advocate peeing on your lawn instead of buying fertilizer. Major countries such as Sweden, Australia, and the United States are looking into urine-based fertilizer to decrease waste and dependency on fossil fuels. With so much opposing information, it can be hard to determine who’s telling the truth. What if we told you the answer was in the middle?

In a world where pennies are precious, are you wasting your waste? Read on to find out.

Does Human Urine Kill Grass?

The short answer is yes, but it doesn’t have to. Pure urine will kill any plants it touches. However, there will also be an oddly lush ring around the area. This will make more sense as we look at what urine does to grass and why. On the bright side, the chemicals in the urine can also kill pests, so urine can pull double duty if you use it right.

Effects of Human Urine on Grass – And Why

If you’ve ever had a dog, you know the awkward yellow patch an errant stream can leave on your grass. It also has a mysteriously fertile ring around it. But why does this happen? If urine is so dangerous to plants, then why does it still work as fertilizer? It feels like there’s a conflict of some sort. 

To explain how and why urine does what it does to plants, we need to break down what’s in it and why there seems to be so much conflicting information.

Here is a chemical breakdown of urine:

-Water.

-Urea, also known as “carbamide,” contains nitrogen and hydrogen.

-Ammonia is the same as the cleaning agent. Pure nitrogen and hydrogen.

-Inorganic salts include sodium, chloride, potassium, and phosphates.

-Creatinine is a waste product made by your muscles. It is filtered out of the body by the kidneys. Generally speaking, this is not a harmful chemical, but high creatinine levels may indicate kidney issues.

-Urochrome is the “natural color” produced by the bloodstream. It is not harmful, but if your urine is not a healthy yellow, do not use it as fertilizer.

We will focus this discussion on the first four components on the list: water, urea, ammonia, and salts.

Water is the most prominent component of pee. Urine is 95% water; if your urine is syrupy, be concerned. Otherwise, this water content should make it good for plants by default.

Then we get to the chemicals. Urea and ammonia both contain nitrogen and hydrogen—critical elements for photosynthesis. Some places sell urea fertilizer as a cost-effective nitrogen booster; if the dirt in your area is low in nitrogen, it may be worth a try. Urea can work wonders, but there are other things in urine.

Ammonia is similar to urea but not identical. Nitrogen and hydrogen, the sole components of ammonia, are both very good for plants. Ammonia also makes urine more sterile than manure. At first, this seems like a no-brainer because it makes sense on paper, but in practice, ammonia is often too strong to be healthy for plants. An experiment by Miami University tested ammonia-based cleaners on plants; both test solutions eventually killed the specimens. It’s too much of a good thing.

But the real death blow for plants is salt. The salt in urine is enough to kill plants for sure. Sodium chloride (table salt) can only hurt plants; gardeners cannot use salt as a weed killer. Phosphates and potassium are both safe and highly desirable for plants, but the salt content makes their benefits moot. Without following the proper procedures, you are salting the earth when you pee on your lawn. 

The short version is that human urine has some things plants love, other things plants hate, and some good things that are simply too much. Hopefully, that was clear enough that you didn’t need to go back to chemistry class to understand it!

Can Human Urine Kill Grass and Weeds?

Yes, urine can kill plants, especially if they’re young. The salt content in urine makes it toxic to plants. If you’re low on money and have excellent aim, you can kill weeds by peeing in the right spot. Do not plan any other gardening projects in the area, however.

How To Clean Up Human Urine on Grass

If you pee on your lawn and need to clean it up, just add water! Whether it’s a dog mess or your mess, hose the area where urine has been liberally applied to your lawn. Adding other chemicals will only make the problem worse. Reseed if necessary.

How to Use Human Urine on Your Lawn Safely

The safest way to use urine on your lawn is to dilute it. However, the exact ratio can vary. The easiest is a 2 to 1 ratio or twice the amount of water as urine. Measure carefully. The point remains that raw urine is not good for your lawn, but diluted urine is.

There are still a few catches. If you want to fertilize a houseplant, you will need a different ratio than if you wish to give your lawn a golden shower. It also depends on your local climate; hot, dry areas demand a higher water-to-urine ratio. Do your research before using your urine as fertilizer.

But fertilizing plants with pee can yield amazing results. Science Report details a massive experiment where sub-Saharan farmers in Niger fertilized their crops (pearl millet) using a blend of diluted urine mixed with animal manure fertilizer, then diluted urine alone. After they added the urine mixture, their crop yield increased by 30%. The images of regular versus urine-fertilized plants speak for themselves.

There are also some concerns about bacteria in urine fertilizers. Most of the time, your diluted urine will be perfectly fine to use as fertilizer. The risk increases when multiple people donate urine, or when people are not clean when they pee. We mentioned that urine is sterile due to its ammonia content earlier, but the fecal matter was not so clean; the biggest risk in urine fertilization is the crap that might slip in. Other than that, diluted urine is safe.

If you want to try using urine as fertilizer for your lawn or garden, start small. Create a 1:1 or 2:1 solution of water to urine. Try it on different plants or parts of your lawn. This science experiment is safe and easy to do at home. There are also some companies and specialized waste services that will put your pee to good use if you do not feel like mixing things yourself.

Conclusion

At the end of the day, is it worth peeing on your lawn instead of using a toilet or buying fertilizer? Not unless you know what you are doing. Think before you do your business. You can try this at home, but not by using urine straight from the tap. Find a dilution ratio that works for you, because some components of urine are too much for plants to handle. It can nonetheless be a great way to save money once you find the right ratio. If you decide to use your urine for fertilizer, drink a lot of water and avoid salty snacks for a while. Your lawn will thank you.

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