Here are a few possible explanations. From your pics, you can obviously grow some nice grass. Unfortunately if that is where your dogs do their business, then that grass is being overfed, which looks nice, but it isn't an ideal situation. I have a friend who has this same problem, and while it is lush and green, it is forcing the grass to grow and use up it's reserves before it really needs them. So the good grass is somewhat artificial in that the large amounts of urea put down by the dogs is masking the issues affecting the bad grass. While you say you have clay soil, which may be true, but the majority of people that say they have clay soil actually don't. You can do a test yourself to determine your soil structure if you want, it's called a jar test for short. Also check the soil with a long screwdriver in areas of bad grass. If it goes in relatively easy, and to a depth of at least 6 inches, then that's good. If you have trouble, or hit rocks, or a rock ledge, then that can have a negative affect on your grass. So here's what I would do. Check your soil with a jar test, and with a screwdriver test. More importantly I would recommend you send your soil to a good soil lab for a soil test (www.loganlabs.com , $20 basic soil test). I remember when I felt I didn't need a soil test but finally did one only to discover my pH in my front yard was 5.5, and 4.5 in the back! You cannot grow nice grass in poor soil. Growing grass isn't rocket science, it's a plant, all it requires is enough sun, water, and good balanced soil, and that's about it.

Is your dog the only one doing fertilizer??? ;-)

When was the last time you fertilized and what did you use?
How often do you water and for how long?
How high/low do you mow? ...and I realize you have not mowed the short grass yet.
Would you be interested in an organic approach? As I recall Indiana has some of the best prices for organic fertilizers.

Thank you all for your posts!
We truly have clay soil. The screwdriver test is good today (we just had 1 day of good rain) I did a home soil test at 6.5ph (I don't know how accurate this is). No rocks or debris.

We've had unbelievably warm temps since March 1 (warmer than other NE areas)
I fertilized 2-3 weeks ago. I used the Jerry Baker fertilizing method. (2) doses of 1/2 amount of fertilizer+Epsom, spread 1 week apart) followed up by an over-sparay of his lawn tonic (beer, ammonia, soap, sugar). i also preceded this with Lime, Gypsum and bone meal (2 weeks before)

I can see what you mean why the grass might be getting supercharged by the urea, and we are left seeing the regular poor grasses. However, I'd think those poor areas would be vigorous by now, (they have always looked poor in 3 years).I pulled up some samples of grass and I think I identified them as hard fescue. Like I said it seems that the "other" grass in between the clumps died out. THe grass that is left seems very different from the rest of my lush lawn.

I will be doing some aeration very soon (last one was in the fall) I might me open to organic fertilizers too, anything...
thanks

Why on earth would they be vigorous???? You haven't fertilized. FERTILIZE. Your grass is starving. It won't get fat if it doesn't eat!

Do not thatch. Do not plant seed this time of year. Fertilize. And water if it needs it. If you fertilize, all your grass will look great. Don't dethatch. You're removing dead grass that is protecting the bare soil from drying out. It does not need dethatching. Do not aerate. Looking at the pee spots, your grass doesn't need it.

Clay soil can be the best soil. I have clay soil, and in good areas, I have 8" and more of rich, humusy topsoil that's been built on top of it. This happened because the plants were happy, which made the microoraganisms happy, and I mulch absolutely as much as I can.

Hello
Did you not read my post?? I have already fertilized this spring.
Okay I won't thatch but how will those bare spots fill in it seems the variety left is a clumping type that won't fill in like the rest of the lawn.
Okay and to be clear all the healthy grass is NOT only where the pee spots are. I have an entire section that is filled in green and healthy. I can get more picts if needed.
There is no humusy topsoil in these poor areas!
thanks for your comments

There is good info in all these messages, but I can see where it might be getting confusing. Don't know if this will help but I'll give it another shot.

If you do not have a brick making plant within 2 miles of your place, then please do a jar test. Voice of experience again here. When people do the jar test, more often than not they come away understanding they do not have clay but something else. We happen to have a brick making facility about 50 miles from us, but that clay is an outcropping. There is no clay around here for hundreds of miles - except that one spot. We have soils around that act like clay because they have too much magnesium (Epsom salt) in them.

Jerry Baker was a really nice guy, but if everyone did what he suggested, half the people would have dead grass and half the people would be happy. I believe you are verging on the half with dead grass. His potions and sprays work better on shrubs, in my opinion, than on lawns. Lawns are very heavy nitrogen feeders. His system does not focus on that. It turns out lawns feed best when the soil chemistry and the soil biology are at their best. Soil chemistry can only be improved after a good soil test which shows you the amounts of P and K (N is always deficient), pH, and the levels of the micronutrient chemicals in the soil. The micros will tell you why your soil acts like clay. It could be you need Epsom salts, but Jerry Baker could not possibly know whether you do or not. If you already have too much magnesium, then Epsom salt will drag your soil into a much worse condition. And too much magnesium mimics a hard clay soil. The micronutrients from the test will also tell you what needs to be improved in YOUR soil. You can usually find those micronutrients on eBay or at the grocery store. Believe it or not the beer, ammonia, soap and sugar is the best thing you've done so far. Do that again and you won't have to aerate.

You have two different kinds of grasses in your lawn. You have the fescues, which grow in clumps, and you have something that is a spreading type of grass. Kentucky bluegrass is one that spreads as is creeping bentgrass. Many people mix fescue and KBG because they both take similar care. Bentgrass, on the other hand, takes different care so it is usually considered a weed in a fescue lawn. I am thinking bentgrass might be what is causing your issues. Why? Because KBG would be up tall by now. Bentgrass grows low. Your best bet in determining your grasses is to take samples to a local nursery familiar with the different types. This would NOT be Home Depot, Lowe's, or Wal-Mart. Look for a nursery that has been in business for 30 years or so.

The fact that the dog pee spots are doing much better is a very strong indicator (a dead giveaway) that your soil is weak on nitrogen. It could be you fertilized before your roots were ready to take up the nitrogen in the spring and it has since washed away with rainfall and all the irrigation you're using.

I'm going to suggest you continue to thank and admire Jerry Baker for bringing you closer to your garden, but for lawns, I'm going to give you the wisdom of my years and years on this forum.

2. Water deeply and infrequently. Deeply means at least an hour in every zone, all at once. Infrequently means monthly during the cool months and no more than weekly during the hottest part of summer. If your grass looks dry before the month/week is up, water longer next time. Deep watering grows deep, drought resistant roots. Infrequent watering allows the top layer of soil to dry completely which kills off many shallow rooted weeds.

3. Mulch mow at the highest setting on your mower. Most grasses are the most dense when mowed tall. Bermuda, centipede, and bent grasses are the most dense when mowed at the lowest setting on your mower. Dense grass shades out weeds and uses less water when tall. Dense grass feeds the deep roots you're developing in 1 above.

4. Fertilize regularly. I fertilize 4 times per year using organic fertilizer. Which fertilizer you use is much less important than numbers 1 and 2 above.
   

When I came to GardenWeb I was not on board with these three key elements of lawn care. I learned them here and share them with people who are not likely to hang out here for 10 years.

I like organic fertilizer for a couple reasons. First is it really works. For unknown reasons my lawn stopped responding to chemical fertilizers after several years. Organics worked right away. Second reason I like them is I can fertilize with organics all summer long without fear of burning the grass. It just gets better. Third reason is it is very hard to make a mistake with organics. Using too little is about the only mistake. Using too much is only better for the lawn. Fourth reason is my garage no longer smells like chemicals. Fifth, it is probably much better for my dog than chemicals. Proof of that seems to be growing but I'm not expert enough to give a good argument. If you are interested in learning about the modern approach to organic fertilizer, go to the Organic Gardening forum and find the FAQ. The Organic Lawn Care FAQ is at the bottom. It was compiled from questions asked/answered here and on other forums.

Then those are likely the spots you missed, or higher spots that lost a lot of the fertilizer to lower spots. It's very easy not to fertilize everything.

If the grass is green where the dog pees, then you need fertilizer where it isn't green. And you may need more water, too, if it's been dry--deeply and once a week to (in a VERY hot climate where it's been VERY dry) twice a week. You should be fertilizing 3 (if you mulch) to 4 times a year for a lush lawn. If all it takes to bring back the brown areas is a bit of dog pee, then, yes, FERTILIZE.

And I do very much recommend mulching. This does not cause thatch build up. It adds compost to the ground without you having to drag it around.

8 years later. Did you fix your problem. I have identical issue. No pee in case so that is not the problem. Area had that before. We turned the soul, fed it, reseeded. It all grew beautifully and started to die down in between. I watered the hell out of it as air grew and then regularly. For a time I thought it may be overwatering but it is not either