From what I’ve heard, New Zealanders are intimately familiar with the movie The World’s Fastest Indian. In it, Burt Munro (Anthony Hopkins) tells another character to pee on his lemon tree while he’s away, and claims Confucius said it’s the world’s best fertilizer. So, while this movie ignited the wide-spread idea of peeing on citrus trees, is this really true? Do citrus trees like urine?
Urine makes a good fertilizer for citrus trees, but it should be diluted or composted first. Urine is high in nitrogen (also called urea), so it can be too potent for citrus trees on its own. For best results, dilute each part of urine with 10 parts of water. Urinating on citrus trees on occasion won’t harm them.
So, while peeing on your citrus trees can be an odd practice, it can prove to be a great fertilizer. But what exactly does urine do to the soil, and can it kill citrus trees in higher amounts? Let’s take a closer look (but not too close).
Why Urine is Good for Citrus Trees
Urine (uric acid) is good for citrus trees in small doses. Typically, urine has an acidic pH and high nitrogen levels, which are both things that citrus trees prefer. However, even though the nitrogen, phosphorus, and potassium (NPK) found in urine can benefit citrus trees, you should first dilute it at a 1:10 ratio.
Citrus trees prefer a pH of 5.5-6.5, and with urine normally ranging at a pH between 4.5-7.8 (depending on one’s diet), it can typically offer an ideal pH for citrus trees.
For those of you who are more serious about regularly urinating directly on your citrus trees, consider first testing your urine with pH strips.
If it’s too acidic (below 5.5) you can add some wood ash for alkalinity. If it’s too alkaline (above 6.5) add some coffee grounds for acidity.
In any case, the nutrients found in urine are too high in concentration to be applied directly to the tree. Adding urine to your compost pile or diluting it 1:10 first will ensure it does not damage the tree.
One of the biggest problems in capturing urine to use at a later time is that ammonia starts to build up, and it starts to STINK.
Therefore, if you’re diluting urine, make sure to apply it fairly quickly to prevent it from smelling. If you’re composting it in your compost piles, you shouldn’t have to worry about the smell, as long as you turn the pile occasionally.
Depending on the amount of urine you’re adding, it may be a good idea to check the pH of the compost as well to see if it’s getting too acidic.
Is Human Urine Good for Citrus Trees?
Human urine is good for citrus trees as long as it’s low in sodium and diluted. Sodium levels in urine largely depend on diet. With the Standard American Diet, excess sodium, preservatives, and medications are often present and can pass through urine, all of which are often harmful to plants.
Additionally, diets too high in protein can cause excess nitrogen levels and can be harmful to citrus trees.
Citrus trees prefer an NPK ratio of 2:1:1, so the 11:2:4 NPK found in urine has about 5x the potency of preferred nutrients. This is why mixing urine with 10 parts water is so important.
If you’re going to be supplying citrus trees with urine, start with small volumes in low doses. If the citrus tree’s leaves start turning yellow or dropping, stop the application and water the tree’s soil heavily to dilute the remaining urine further.
If you’re finding that urine isn’t providing enough nutrients for your citrus tree, and you’re interested in getting a good fertilizer, check out the citrus fertilizers I recommend.
Is Dog Urine Good for Citrus Trees?
Dog urine is good for citrus trees as long as it’s not a daily occurrence. If your dogs regularly pee on the same citrus trees, the tree can become overloaded with nutrients and start to die. Consider training your dogs to go elsewhere, or water the tree more often to dilute the nutrient concentration in the soil.
I don’t know about you, but when we take our dogs out to the yard, they usually pee in the same spots. Because of this, the grass normally turns yellow and dies. It makes our yard look like Swiss cheese.
This happens because of the potent nitrogen and nutrients levels. It’s simply too strong for the grass and chemically burns the roots.
This also applies to larger plants. We have a certain shrub in the backyard that our two cattle dogs always used to pee on. After only a week or so, the leaves turned from a deep green to a bright yellow.
After watering the shrub to dilute the existing urine in the soil, and training our dogs to not pee on it, the deep green returned in another couple of weeks.
While citrus trees are obviously much larger than shrubs, it takes more urine to start killing the plant (although not as much as you think).
Normally, you don’t need to worry about your dogs urinating on your trees, but if it gets excessive, increase how often you water the tree or consider putting deterrents such as small fences or cayenne powder around the trees.
Can Urine Kill Citrus Trees?
If citrus trees receive urine, especially in a dry season, it can chemically burn the roots and kill the citrus tree. Additionally, any medications or diets that are high in sodium can pass in urine and negatively impact the citrus tree. Urine is unlikely to kill citrus trees if it’s diluted or composted first.
The first signs of citrus trees dying from excessive nutrients, such as those found in urine, are yellowing leaves. If you see the leaves yellowing and are fairly certain it’s from the urine, then pause or lower the volume of urine you’re using.
There’s some truth that urine is “liquid gold” for the garden. The nitrogen, phosphorus, potassium, and other valuable nutrients and minerals are incredibly beneficial for citrus trees. However, citrus trees are unable to use the high volume of nutrients in urine.
If the citrus tree is occasionally exposed (pun intended) to urine, whether it’s from you or your dogs, it won’t kill the tree.
However, if you’re intending to do a permaculture-like approach, and would like to recycle every nutrient for your garden (including urine) consider processing the urine first by dilution or compost.
If you’re interested to see how an Australian gardener processes urine on his permaculture farm, check out this video by Happen Films. It’s just a quick look at their setup, but it definitely sparks some ideas (spoiler: it’s just a hay bale). I’ve linked the specific time in the URL (5:54), so it should take you to the right spot in the video in case you want to virtually tour their farm.