Where do you live?

What kind of grass do you have?

80 degrees is not warm enough to cause a problem. What is your watering schedule? How often and for how long do you water?

Top dressing with compost was the best advice available from the 1930s to the early 2000s. Now it is recognized by a growing number of people as the slowest and most expensive way to improve the lawn. Compost is a pile of depleted organic matter. If you want active organic matter, use a real organic fertilizer. Many people use Milorganite for several reasons. I like alfalfa pellets, soybean meal, corn meal, or corn gluten meal as raw organic fertilizer products available everywhere at your local feed store. Not all of those products will be available but one of them will be (alfalfa pellets are also rabbit chow). In my area the cost of compost delivered is about $75 per 1,000 square feet. Organic fertilizer is more like $5 per 1,000. Apply at a rate of 15 pounds per 1,000 square feet. You can use is safely as often as you can afford (every day or every month or every year). Here is a picture showing how organic fertilizer works.

Mrmumbles posted that picture many years ago. He applied alfalfa pellets in mid May and took the picture in mid June. You can see the improved density, color, and growth. This picture has convinced lots of people to at least try organic fertilizer.

Unless you live in a brick producing area, the topsoil your contractor used was unlikely to be clay. It might have been poor soil, but not clay. Only a soil test will tell. The best soil test lab in the US is Logan Labs in Ohio. Their $25 test will tell us and you all you need. Post the results here and get a good review of it. You might test both areas if you think the soil quality is considerably different from one to the other.

In the mean time, spray your soil with 3 ounces of shampoo per 1,000 square feet. Use any clear shampoo - no additives like conditioners. Follow that with 1/2 to 1 inch of water and give it 3 weeks to take effect. After that when you water deeply or it rains, the soil should be noticeably softer to walk on. Do the fork or screwdriver test before and after to judge the effect. Test it several times. I did the test this weekend and got different results just a few inches apart. Once it is sprayed it should be soft when moist and very firm when dry between waterings.

Adding new soil will not necessarily help. One problem with new soil is that it changes your drainage. You don't want to create a dam effect where the rainwater backs up into your house or basement. Water should drain away from the house for at least 10 feet. Another problem with new soil is that it will not be perfect, either. It will need the same $25 soil test to see what's wrong with it.

I think the issue is adding organic matter to break up or aerate the clay rather than the purpose of adding nutrients. For that reason alone I would continue to top dress with compost, and especially after any core or plug aeration. Not sand and not even topsoil. You need something more textural with a larger particle size to filter down into those voids and add porosity and chunky organic matter - like compost - is still the best product for this purpose.

You also want to leave the plugs in place to breakdown on their own. After a single mowing, they will help in the same way the topdressing of compost will.

btw, compost is not just a pile of "depleted organic matter". Depending on ingredients, it can carry a nutrient load very similar to that of most organic ferts and is still very biologically active, even when considered 'finished'. Which it is not and won't be for years....perhaps even decades.

Compost is absolutely depleted organic matter. It is the very definition of depleted organic matter. Compost begins as a freshly discarded salad bar of salady things from the kitchen, coffee grounds, lawn clippings, tree leaves, and hopefully lots of fresh animal dung. Compost is declared to be "finished" after all the microbial activity has stopped, the pile has cooled down, and the fresh aroma of soil (provided by the final stage of composting organisms) has come about. At that point the only bits left are woody. The vast majority of microbes have been consumed by the later stages of microbes. All the food value of the original salad bar stuff is long gone leaving the accumulated waste materials of the previous generations of microbes. Once those are depleted by follow-on generations of microbes, there is nothing left but waste materials that have no immediate food value. If it had immediate food value, there would be more microbes coming by to deplete those. If you want to call the glacial speed of wood rot to be biological activity, then we agree a little bit.

And for a practical example, it takes 15 pounds of organic fertilizer per 1,000 square feet to get 1 pound of nitrogen. It takes 700 pounds of compost to get that same 1 pound of N.

The best way to get chunky organic material in the soil is to grow grass. Grass plants slough off about 1/3 of their roots every year leaving chunky bits of grass roots in the soil for the dining pleasure of the soil microbes.

Whether the OP has clay is up in the air with the odds going way far against the possibility of having much clay at all. After reading forums for 15 years, only a handful of people actually have measurable clay in the soil.

"Compost is absolutely depleted organic matter. It is the very definition of depleted organic matter."

LOL! Not even close! You are confusing compost with humus and they are NOT the same thing. Microbial activity is never finished with compost until all possible decomposition has occurred. And if you know anything about compost you would know that doesn't occur until it reaches the humus stage. And that doesn't happen for a very long time - years to decades, depending on ingredients and conditions - and the product is not fully "finished" until that happens. If it were as 'depleted' as you infer, it wouldn't continue to shrink in volume (indicating continued decomposition going on) nor would it test out as having any measurable nutrient levels.

Except under very sandy soil conditions, virtually all soils have a clay component. A basic beginner's Mason jar test will confirm that. In fact, an "ideal" soil is considered to have clay, silt and sand - the three standard components for soils - in almost equal proportions. And that 'handful' of people will grow exponentially if you ask in Georgia, Alabama. Mississippi or anywhere else in the southeastern US that has utisol soils, anyone gardening with Texas black gumbo or much of the glacial till that makes up soils in the northern tier of states. Predominately clay soils are an uncommonly typical gardening condition!!

Thank you all for the great comments. I live in Western New York and the weather is just starting to warm up.

When the lawn was first seeded, the contractor my better half hired graded and seeded the lawn hours before a torrential downpour. When I returned home from work, there was seed in the street and the dirt actually had ripples in it. When I tried to reseed it, I could not penetrate the surface of soil jumping on a 4 prong fork. I assumed it was clay because it was very hard not like typical topsoil. In the rear of the house the contractor did not put enough soil and I had a small lake. I added 10 yards of tops soil to grade it correctly and that area is always thick dense grass. I will look to get the soil tested.

I normally use Scotts Fertilizer, especially the Halts to stop the crabgrass and nutgrass. Can I use the Milorganite or organic with the Scotts or is that too much. I want to slow the weeds.

I did try to top dress a 400 sq ft area with town compost last year but I don't notice any difference, I did not plug that area first. Given I'm dealing with a herniated disk I may try the organic fertilizer first.

I should add that in the summer I spray detergent on the lawn based on the Jerry Baker book to break the surface tension of the soil. . Last year I also sprayed Aerify Plus but it just seemed like expensive soap. I didn't see a difference with the Aerify Plus as I sprayed some test areas too.

Weed and feed is considered a bad product as it supposedly kills the good microbes in your soil. I would go with an organic fertilizer like Medina has its slow release and has trace minerals and such that your lawn may need.

General idea is to keep feeding the lawn and mow often and let the grass overtake the weeds. Nutshedge is the worst of the weeds. If the weeds are seeding, use a bag on the mower.

Also, people will tell you to use shampoo, molasses, product x, etc. There hasnt been much for research behind these products; try to find a published peer reviewed research paper from any university that and you wont find any. Just bloggers and radio hosts who say its helpful, many of them trying to sell you something. Stick with compost and an organic fertilizer and you should be fine.

Uh, yes there is research, quarzon. You have to know what you're looking for. Once you use the right search terms, you won't be able to read it all. There is a lot of research on surfactants and stickers. Keep looking. Keep in mind that universities are not paid by the shampoo manufacturers to do research on grass, but they are paid by other surfactant manufacturers to do research on grass. Shampoo is simply a poor man's substitute. And I absolutely cannot believe there are people who will spend weeks of research and decide not to spend $0.50 on shampoo because they cannot find the peer reviewed, double blind, placebo controlled research. Just try it and join the rest of us who have. Shampoo on small lots is as good a surfactant as Cascade Plus is on acreage.

I'm not selling anything. What I'm doing is simplifying the life of home owners trying to take care of their lawns. Why not spend fifty cents on shampoo instead of breaking your back and spending $75 to rent a core aerator which does a much worse job? Shampoo is a "best practice" evolved from the research.

Molasses is a biological. It is food for the beneficial bacteria living on plants and in the soil. I will agree with you that the jury is waaaay out on the effectiveness of using it, but I use it on my tomato plants all season long to keep bugs off. Molasses is also used as a sticker, because it coats the surface of plants to block the waxes that cause hydrophobia. Let's not drift off topic, though.

For Gardengal the point of the discussion is that organic fertilizer is much more effective and much less expensive than compost to do what the OP wants. For practical purposes, compost is 99% depleted materials. Just look at it. It requires a mountain of feed stuffs to make a molehill of compost. The microbes that created the compost are dead and gone. They have been consumed by other microbes which are dead and gone. The remaining value is in the sticks and twigs and the fraction of beneficial microbes which decompose the woody remains. Those sticks and twigs are micromulch which has value in other ways.

And what search terms should i be using? Can you provide links to this research?