Dog Urine can Damage Lawns

Dog urine can significantly damage lawns

Brian Jervis: Ask a Master Gardener

Saturday, March 19, 2016

Q: I have some brown spots in my fescue lawn, which I think is due to dog urine. Is this likely and if so, what can I do about it? Irene, Tulsa.

A: Well over a third of all households have one or more dogs. This amounts to 70 million dogs in the U.S. We all love our dogs, and we benefit immensely from their companionship. However, when they urinate on our lawns, they can cause significant damage.

The damage to grass from urine is due to the high concentration of nitrogen and soluble salts. It is not related to acidity or any other chemical contents. Dealing with the issue is difficult. Dog urine damage has been much discussed — some information is factual and others are no more than urban legions.

The effect of urine on grass is similar to applying an overly-concentrated solution of fertilizer, resulting in “fertilizer burn.” The amount and type of damage depends on how much and over how big an area the urine is spread. If the urine is dilute, burning does not occur, and the spot may even eventually turn green related to the nitrogen effect. This is similar to the green clumps of grass often seen in cow pastures associated with cow urine.

Studies have shown that fescue grass is more tolerant than Bermuda, but if damage occurs, Bermuda is able to fill-in and repair itself, whereas fescue cannot.

Also, the damage seems to be greatest when the soil is dry and the grasses are not actively growing. Lawns that have been heavily fertilized also seem to be more susceptible to damage.

Female dogs and puppies tend to squat to urinate in a small space. This is much more likely to cause damage than males, who tend to spray urine over a larger area. When females urinate in a small spot, it usually results in a brown patch with a dark green halo, called “female dog spot disease” by some turfgrass experts.

Studies have shown that the only practical diet modification that may lessen damage is to make sure your dog drinks enough water. This results in a more dilute urine. There is no indication that diet modification to change the acidity of urine is useful.

To prevent damage, the obvious solution is to restrict the area or retrain your dog to use a dedicated site for urination. One thing that can be done, which is doable but not practical, is to hose down the area of urination. Studies show that if you apply water 3 times or more of the volume of urine within 8 hours of pet urination, it will prevent turfgrass kill but not the green-up effect.

It is a tough choice whether to have a pet and perhaps tolerate some damage to your lawn. However, the benefits of having a dog usually wins out over the appearance of the lawn.

For more information or to ask a question about gardening, contact the Master Gardeners at 918-746-3701 from 9 a.m.-4 p.m.

Garden tips

§  Cool-season lawns such as tall fescue, bluegrass and rye grass may be fertilized now with the first application of the season. Usually, four applications of fertilizer are required per year — in March, May, October and November, with the fall applications being the most important. Never fertilize these lawn grasses in summer.

§  If you scalp (cut very short) your Bermuda lawns now it will green up faster. However, it will also be more susceptible to weed invasion when cut short.

§  Start your routine fruit tree spray schedule prior to bud break. Contact the Master Gardener Office for a document outlining recommendations for all fruit tree types — they are not the same.