Why Does Dog Urine Stain the Grass?

urine burnMost homeowners let their dogs use the backyard as their own personal toilet. Often after a winter of such potty practice, when the snow melts, you’ll often find your lawn speckled with unsightly yellow patches.

First of all, what causes these patches? Dog urine contains a variety of nitrogen compounds. Too much nitrogen will burn the grass and create yellow patches. But appropriate concentrations of nitrogen can actually be beneficial to the lawn, which is why you’ll often see rings of thick dark green grass around the yellow patches. This makes sense, since the main ingredient in lawn fertilizer is nitrogen.

The concentration of nitrogen in the dog’s urine depends on the type of dog, its sex and what the animal eats. Larger dogs will pee more and cause more damage. Female dogs also tend to cause more damage than males because they squat and urinate in one concentrated patch whereas the males spray their urine over a larger area. Finally, diets high in protein can increase nitrogen concentration in the urine since protein breaks down to release nitrogen compounds.

So how do you prevent the appearance of these unsightly patches? There are two ways – change the nitrogen concentration of your dog’s urine or focus on the lawn. You can start by changing your dog’s diet. Feed the dog food with lower protein content so there is less protein and subsequently less nitrogen in the urine. Many dog foods on the market actually have much more protein than an average dog requires. You can also try to dilute the dog’s urine by watering down the food. Or you can deal with the lawn directly by spraying the patches with water or treating them with gypsum pellets (made up of calcium sulfate hydrate) which expand in water to break up soil. You may also want to designate a certain area of the yard, such as a rock garden or gravel patch, as the area where your dog should urinate then train the dog to go there every time.

Another suggestion has been to give the dog tomato juice to neutralize the nitrates in the urine. This does not work and is scientifically unfounded. Then there are products like Ammonil or Green-um pills to try and neutralize the ammonia in the urine, or lawn care products like Dog Patch Spot Repair to be sprinkled on the yellow patches. Watering the lawn might be a cheaper alternative.

Finally, if all else fails and you simply can’t tolerate those yellow spots any longer, there’s one last option. You may want to consider getting a cat. Hopefully, however, it won’t come to that. And with a little careful monitoring of your pet and the lawn, you can let your dog out of the house (and the dog house) without worry.

Joe Schwarcz

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