It takes three years for soil to settle. Now would be a good time to level it again - finally. Looks like you have several types of grass in there. Do those tracks show all the time? It could be they drove on the soil when it was wet and compacted it some. I would start to fix that by spraying with baby shampoo. Spray the entire yard. Spray and then follow up with a full inch of water as measured by empty cat food or tuna cans. While you're doing that, time how long it takes to fill those cans, because that is the time you should be running your sprinklers when you run them. Then the next time you water, repeat the shampoo and deep watering. This sets up your soil to grow the beneficial fungi which will soften your soil. Oh the application rate for the shampoo is anything higher than 3 ounces per 1,000 square feet. With temps in the 50s you should be watering about once per month. When it warms up you can increase the frequency. If it only gets into the 80s, then you can water every 2 weeks. If you get daily temps in the 90s then go to once per week. Mow at the mower's highest setting. That, along with infrequent watering, will help keep weeds out.

Oh my! You are getting some very poor advice. At every turn, you are going the opposite direction you should go. If you are lucky, your grass is only going dormant from the summer heat. If so, keep watering but not nearly so often. First you seeded in the spring. Spring seeded grass can only live through a summer if the summer is cloudy and you get rain weekly. That has not been the situation this summer. The little roots you have on the grass are too tender and too close to the surface to survive. So what you are seeing would be considered normal for a year like this one. Chemical fertilizer should be applied one time in late spring and then not again until Labor Day or so. The salts in the chemicals during the summer stress the roots of even established lawns. The chemicals also force the grass to grow in the summer heat when it should be trying to go dormant. Organic fertilizer may be used at any time in the summer, but you are, again, forcing growth where you may not want to. You are going the wrong way with your watering. You were probably watering too frequently to begin with. Once your lawn was established in April, you should have backed off on watering frequency and increased the duration. Normally in April you would be water only one time. In the summer you need to increase the frequency to once per week. What this does is encourage deep rooting which can withstand periods of heat and drought. You have short little roots which can withstand neither. And do not water at night unless you are forced to by local watering ordinances. Sure it rains at night but don't tempt fate. It seems to be better to water in the early morning so the blades of grass can dry off and not develop disease. First thing to do is stop mowing. Tall grass grows deeper roots and can withstand the heat and drought better. When the heat breaks or you get rain, you can mow at the mower's highest setting. Secondly, back off on watering. If the grass is dead, you cannot water it back to life. If the grass is dormant, you might rot the tops of the plant with all the water. Just let it be dormant or dead until the heat breaks. Water once per week. Water about an inch when you water. Measure one inch with cat food or tuna cans places all around the yard. Different watering systems water much differently. Yours will likely put out an inch of water between 20 minutes and 8 hours. That seems to be the range I've seen posted around the forums. It is best to apply one inch per week in the hottest heat of summer and one inch per month in the cooler months. Apply the full inch all at one time. Use that as a starting point. One inch may not be enough for some dry spots and it may be too much for some shady spots. The idea of waiting between watering is to allow the surface of the soil to dry completely. The deep roots need to be moist, not the surface. Plan for another renovation this fall. Fall is the time to renovate because the summer weeds are dying out. The grass will have time to develop deep roots before the summer of 2013 and you should have a much better year. If you decide to do that, please post your ideas here for that project. There are some major mistakes you can avoid by discussing it first.

I live in Minnesota and I have noticed the same thing as what others have said. I noticed it around an area of where our old (cut down) Oak tree was. I have been trying to grow some grass there for a while. We have had some rain, but this is in a sunny location on a hill. The spot looks black from a distance but up close it looks like brown fungus covering the grass and some weeds. I took a stick and brushed over it and it clouded up kind of like the smoke balls that we seem to get once in a while here in MN. We also have some white powdery looking stuff in a smaller area by the black fungus stuff. I'll try and mow over it and see what happens. I'm worried my dog will get into it and get sick.

Hi, Thanks for the reply! Well, it's Iowa. So the saying goes, if you don't like the weather, wait 5 minutes. :) It's been mostly hot and humid all summer, 80+ degrees. I don't know what "prolonged" periods of rain are, but it has been storming a full 8 hours about once or twice a week this past month. I watered about every other day in the spring at around 5pm until the grass was established, and about the same lushness as the already growing grass (middle of the lawn.) I stopped watering after that since it rains 1-2 times a week. I have no idea what kind of grass I have. I'm guessing some sort of bluegrass/ryegrass mix from my quick google search. The good grass on the center of the lawn is very dense. I'd like to match that the best I can in the dead spots. Planning on seeding a mix. The arrow in the second picture points west. The problem started on the east side of my lawn. Weirdly though, peeping through my wooden privacy fence, my neighbors grass (that would be touching my grass in that first picture) is green and looks undamaged. I have no idea how long the mud lasted. I moved into the house in mid-November, and immediately raked a ton of leaves that had been sitting for months off the lawn and discovered all the mud. After winter, I planted grass and it seemed fine. The grass was already growing (no new seed) in the "starter spot" of the dying grass. But the last picture (North corner of yard) was new grass this year.