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. At first I visualized rocks that were 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 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 can be in quite high levels in dog urine and chemically it acts similar to glyphosate which is a known herbicide. The level of lactic acid in urine depends on diet and the dogs 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 create 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 dogs 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 there 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!
I experimented, no food change, same water source and only added rocks. The brown spots stopped occuring. Removed the rocks and brown spots appeared. I don’t in why it has effect but experiment showed a difference.
I have a rhodesian ridgeback. He ruined half of my lawn. I bought dog rocks and was extremely skeptical in seeing them but they worked. We threw them once they got covered in algae and now I see burnt patches again so I don’t know how or definitely if they work but they seem to and I will buy again…
Really, never could have guessed!
I rake the pee burn spots and spread clover seed. It propagates very quickly and because Clover loves nitrogen it binds it up. Overall it makes for a healthier lawn.
Thank you for looking into this and sparing me the trouble. I was skeptical when I saw it and your review confirms everything I suspected. I also got a good laugh reading comments of so many people insisting they work despite the “years of research” being total hokum. But people swear by all kinds of things that don’t stand up to scientific scrutiny, and this seems like a harmless and hilarious way for folks to waste their money if they want to.
We tried Dog Rocks and the lawn improved.
Science is more reliable when done using experiments – instead of arguing from assumptions and ill founded reasoning.
Now if the lawn objectively improves, and the mechanism of such improvement, needs to be determined experimentally before reasonably based conclusions can be drawn.
Otherwise we are just working at the level of “paramagnetic reasoning”.
I’ve been using Dog Rocks for about three years, and definitely see an improvement. We soak the rocks in a jug ahead of time, so top the bowl up from the jug and then refill the jug.
They definitely don’t work by absorbing nitrates from the water. Our water is very low TDS (around 30mg/l) so the nitrates are negligible. What I find more likely is the water is absorbing phosphate from the rocks, and therefore you get a high nitrate & phosphate water. We recently bought a new house, and the lawn was freshly turfed. Out the back where the dogs pee we have patches of rapidly growing grass, where I assume the dogs have peed. I need to strim these before mowing them, they’re 2-3 times higher than the rest of the lawn. Out the front, the dogs rarely pee and the lawn all grows at the same rate – no patches of rapid growth.
Some of the patches of rapid growth do have a small brown patch at the centre, and I assume this is because I’ve not changed the rocks in time, or the concentration is just too high and the grass is over fertilised. However, these patches are much smaller than when I’ve not used dog rocks.
My phosphate theory would tie in with them not always working. Phosphate pick up from the rocks would depend on the water pH and hardness, so I can see that it will work better in some areas than others.
As background, I was in water treatment for 40 years so have some knowledge of this. I may look at getting phosphate test system to see if I can measure the difference in phosphate in the water before and after the rocks have been soaked.
If I’m right, then we can stop using dog rocks and just add a small amount of sodium phosphate to the water the dogs drink.
This is very interesting and like to know how we can add sodium phosphate to the water? We have tried reverse osmosis, filtered the water, purified the water, but still have burned grass and we have three dogs. So our backyard looks awful.
Christiane
??? Just add it to water – it is soluble.
I own a female dog.. unfixed.. no problem in the backyard.. BUT she drinks a lot, and pees often.. We always have water available.
To Carl Cargill: I put the Dog Rocks in a large plastic pitcher and I fill the dog’s drinking bowl from the pitcher.
I use dog rocks and find they work very well. I always know if I have forgotten to change them as my grass burns again.
Water should not be rationed and in a good (not pristine) garden there will almost always be other water available.
Anyway if I am not vigilant enough and inadvertently forget to fill dog bowl she will pay me back by guzzling it and then throwing it straight back up….. in the nearest possible location.
Science, ( as proven) cannot yet explain everything…
The “science can’t prove everything” is a common reason people give for their belief in things that science has proven.
Sheesh Robert, you just can’t help but try smack absolutely every comment down. What’s your beef with dog rocks? All these people with experience of them working and all you continually comment is “what’s your proof?”. The proof is in the experience that each of us have had. They worked for me too. Who cares how and we don’t need to prove jack to you. They work, and that’s good enough for me. Oh, and obviously good enough for all those Amazon reviewers also.
You missed a very important point in those positive comments – nobody did a control. That means they did not do a comparison to see if they worked.
You are free to belief what you want – belief does not make it a fact.
https://www.gardenmyths.com/scientific-method-important-controls/