I first heard about Dog Rocks in a Facebook Group a couple of weeks ago. Someone was looking for a solution to the urine burn marks their dog left on the lawn, and Dog Rocks were suggested. Initially, I envisioned rocks being used to cover up the burn marks, but that is not how this product works. Instead, you put the rocks in the drinking water, and they absorb nitrates from the water. As one advertisement put it, “less nitrates going in means less nitrates coming out the other end.” With lower nitrates, the grass is not burned, and your dog no longer creates spots on the lawn.
Normally, when I review products for the garden, I try to be politically correct and bite my tongue, but not this time. This is the dumbest product I have ever come across. A small bit of logic will tell you that it has zero chance of working, and I’ll explain why shortly.
Why Does Dog Urine Burn the Lawn?
The first cause that comes to mind is pH. What is the pH of dog urine? The normal pH for dog urine is around 6 to 6.5, which is the ideal pH for growing most plants. So clearly it is not pH.
The next suspect is nitrogen. We all know that if we spread too much fertilizer on the lawn grass, it burns. The culprit in this fertilizer is nitrogen. Too much nitrate or ammonium will kill plants.
Urine contains fairly high levels of urea, which is quickly converted to ammonium when exposed to water and then to nitrate through the action of bacteria. The common belief is that nitrogen burns the grass, but new research shows that this is a myth. The nitrogen level in urine does not significantly harm lawns.
The real culprit is lactic acid. Lactic acid can be in quite high levels in dog urine, and chemically it acts similarly to glyphosate, which is a known herbicide. The level of lactic acid in urine depends on diet and the dog’s exercise level. Increased exercise can increase levels by a factor of 250.
How Do Dog Rocks Work?
The promoters of this product explain it this way, “Dog Rocks are a paramagnetic igneous rock which creates a magnetic field within the water, causing a change in the ion exchange. This, in turn, diminishes the nitrates that are found in the water.” They claim that the rocks absorb nitrate from the water, which results in less nitrate being urinated on the lawn.
As soon as you see “paramagnetic” anything, it’s a red flag for false advertising. I can’t think of a consumer product where paramagnetism provides any benefit.
No scientific studies are available from the manufacturer to prove any of this, which is surprising since “The product was researched for 4 years and then went on the market.” (reference for quote no longer available) It would only take a few days to put some rocks in water and measure the decrease in nitrates. This would not prove they work, but at least it would prove their theory is plausible.
Interestingly, they do post a report from McGill, Office of Science and Society, which discusses why dog urine has high levels of nitrogen, but this report does not mention Dog Rocks, nor does it put any of the blame for high nitrogen in urine on the water that dogs drink.
As stated above, the most likely cause for dog spots is lactic acid, not nitrogen.
Video on Dog Rocks
Is Nitrate in Drinking Water a Problem?
Most people use home tap water to water their lawn. This is the same water that is used to fill the dog’s water dish.
Why is it that when you water your lawn with this water, you get no grass burn, but when a dog pees on the lawn after drinking the same water, you get a burn? Clearly, the nitrates in drinking water are not burning the lawn!
It is quite obvious to me that the high levels of urea are not from the drinking water, but from the rest of the dog’s diet, and the report by McGill confirms this. A high-meat diet contains a lot of protein, which contains high levels of nitrogen. This results in higher urea levels in the urine.
Nitrogen levels in drinking water are not the problem. So even if the Dog Rocks did as claimed, they would not reduce damage to the lawn.
Do Dog Rocks Remove Nitrate From Drinking Water?
There is no science to support this idea, and the company promoting the product has no data to support their claim. The scientific mumbo jumbo they use to explain their product makes no sense.
It is unlikely that these rocks reduce the level of nitrate in water but if they do, it would be insignificant.
Solving Lawn Spots
There are four things you can do to stop damage to your lawn from dog urine.
- Reduce the meat in the diet. This reduces urea in the urine.
- Water the lawn right away after a dog pees. This dilutes both the nitrogen and lactic acid, and washes it lower into the soil, making your grass grow better.
- Train the dog to pee in the same spot all of the time.
- Get a cat!
They are really great, we have been using them for years!
As long as my lawn is kept hydrated I don’t have a problem with dog pee burn. When it’s dry and he urinates, the grass reacts like I’ve dumped fertilizer in one spot. Simple to fix without using magic rocks or weird pills – use a regular sprinkler.
True, but if you have a dog that doesn’t drink much and urine is concentrated doesn’t always work.
I am a logical person, usually very sceptical when I come across products with apparently unbelievable claims, but Dog Rocks DO work. I have used them for years and the only time I get burnt, dead patches on the grass is when the rocks have been in the water too long and need replacing. They do NOT remove nitrates – the places the dogs have peed clearly get a boost from the nitrogen in the urine, but the grass in the centre of the patch does not die – it just grows fast, and dark green.
When I see a patch of dying grass, I know I need to replace the dog rocks, and then I get no more problems for a month or two.
I usually love Gardenmyths, but I feel this article lacks the usual careful analysis.
Give me one reason why they work?
You seem to agree that they don’t remove nitrates as advertised.
I lamented about this problem of being on a corner lot and grass burns from dog pee to a visiting business owner. He said he fed his dog 1 tablespoon of ketchup daily mixed in with food and he never has a burned lawn even though he only lets his dog pee on his own lawn( nice owner). He said he had done this with a succession of dogs for 25 years. Have you heard of this? I could not verify if there’s any science behind this.
It is a frequent suggestion – I did not try to verify it, but I don’t see any logic as to why it would work, unless it made the dog drink more.
I used them once, and thought they worked for a while. I didn’t read the mumbo jumbo, I just assumed they were affecting the pH of the dog urine- which may be impossible for all i know…
It is certainly worse with female dogs, but as you say, it’s just because they don’t cock their legs, they widdle in the one spot.
I think your concern about expressing an impolite opinion is unwarranted. This is indeed probably the stupidest garden-related product ever! But then, people are apparently buying it… which makes my opinion of them even more impolite than your opinion of Dog Rocks.
Thanks for the more solidly scientific info on just what causes the high urea. I always wondered, and now I know!
This is a wonderful product to separate gullible people from their money. It is one of those products that allow people to something that makes them feel positive without having to either think or do research. You can almost imagine a dog thinking “Oh no! Now I have to slurp my water around these rocks.” At least the rocks don’t appear to have sharp edges to cut the dogs tongues so maybe they did some research after all…
http://www.thatpetblog.com/2013/09/13/do-dog-rocks-work-to-prevent-urine-burn-a-dog-rocks-review/
Just one dog owners experience.
I’ve heard that it is only the pee of female dogs that burns the grass. Since urine from males and females contains (presumably) the same concentration of urea, this too is probably a myth. It may have something to do with male dogs preferring to pee on poles and fire hydrants, and females preferring to squat on the nice green lawn (preferably the neighbour’s!). I don’t own a dog and I work hard to keep my lawn looking nice…and so it really irks me when dog walkers let their dogs pee on my lawn. I am constantly repairing the same little round burn patches with grass seed and just as things start to look better..well, you guessed it. I do like dogs though, and can’t bring myself to say anything to the dog owners. Just wish I could find that magical product that would suggest to the dog that my lawn is not their favourite bathroom.
Both male and female urine is about the same. Males tend to spread it around while females and pups tend to squat and go, concentrating the effect.
Leave one of the spots – and put up a sign that reads, “did your dog do this?”
…or just get your Dog to drink more water so the urine is more dilute?
That works – don’t know how hard it is to do that.
I even wondered if this is why some people report that the rocks work. The rocks may make people fill the dog dish more often? I am not a dog person.