I am often asked about what can be done about dog urine patches on lawns, so I thought I would publish a quick run-down of what happens to the grass to cause it to burn when a dog wee’s on it, and what can be done about it as a lawn owner.
Dog urine contains a large amount of urea. This is a waste product which is the result of the chemical reaction that goes on when digesting the amino acids which make up proteins. Protein (dog food) is broken down in the dogs stomach to make energy, water, carbon dioxide and ammonia (a compound of nitrogen and hydrogen). Ammonia is toxic to the body, so it is converted inside the liver of the dog to a non-toxic compound called urea. This is then wee’d out on your lawn!
Why does dog urine burn grass?
Dog urine is comprised of mostly urea, which is a compound of nitrogen. Nitrogen is the main element contained in lawn fertilisers and urea is an extremely strong version of this. The NPK rating of urea fertiliser is typically 46-0-0.
When a dog wee’s on your lawn it is effectively fertilising it. However, it is putting this extremely strong nitrogen fertiliser all on one small spot. Grass cannot cope with this and dies.
The degree of burn does seem to vary between male and female dogs. However, this has nothing to do with the strength or the pH of their wee, but rather the method of application. Female (and young) dogs will tend to squat, and deposit a large amount in a very small area, concentrating the effects. Male dogs will tend to deposit small amounts from a height and over a much wider area, diluting its effects.
How do I prevent dog urine burning my lawn?
There are a number of effective ways to prevent dog spots.
- Keep your dog off the lawn! Prevention is the best cure. If you want to have a nice lawn, then don’t let your dog ruin it. Be a responsible dog owner and taking it out for walks regularly and not letting it foul the grass. If this can’t be done, then you’ll have to be content with not having a nice lawn.
- Train your dog. Some sources say that you can train your dog to go in certain areas of your garden, or train it to go in a hula hoop, and then move that to a certain area of the garden which would not be harmed by urea. I have not heard of much success of this method though, but I’m sure with patience and perseverance, it can be done.
- Watering in the dog spots. As dog urine is a strong liquid fertiliser, so it can be washed through and diluted by water soon after application. Simply poor a watering can of water on the spot where the dog has wee’d and it will reduce its effect on the lawn.
- Dog rocks. These are volcanic rocks which you add into your pets drinking bowl. The manufacturers claim they purify the water that the dog is drinking, helping to reduce the effect of urine burn on the lawn. Whether or not they work or not is up for debate, with some of my customers saying they do and some saying they don’t!
- Turf Repair Pot. With a little planning, you can easily grow small “turf repair” pots in your back garden. All you need is a small plastic flower pot (3 inch is fine), fill it with some soil, either compost or garden soil, then sow a few grass seeds in the top. Give it a good water and leave it outside somewhere keeping it moist over the next week or so. When your dog has burnt a section of lawn, simply dig out the circle, drop your lawn repair pot grass into the whole and hey presto … fixed! You can set up a number of these pots next to your shed and the grass will sit happily in the pot until needed.
Things you should NOT do
- Give supplements or additives to your dog. Baking soda or other additives change the natural balance of chemicals in your dog. This can be extremely harmful and long term use can lead to serious health problems such as kidney stones.
- Feed them tomatoes. Tomatoes contain atropine, which is a poison to dogs.
- Assume the lawn will recover! It won’t. Lawn burn caused by dog urine kills the grass and it will need to be reseeded.
Lawnscience (South Manchester) Ltd
Further reading regarding dog urine burns on a lawn
- Paper: Allard, AW. Lawn burn and dog urine.
- Northscaping Info Sheet: Lawn Burn Caused By Dog Urine: How To Deal With It
- DogHealth.com: How to prevent lawn burn from dog urine