You can start by stopping the tilling. Grasses that do well in the south will grow on top of your soil without the addition of any more topsoil, compost, leaves, or whatever you read in the newspaper. If you read Neil Sperry in the paper, just do the opposite of what he says. I don't know where that guy lives, but it's not on my planet.

What kind of grass seed did you plant?
When did you plant it?

When you tested the soil composition, did you do a jar test where you shake up some soil in a jar of water and measure the sediment at different times after the shaking? I don't doubt that you have very hard soil, but I am skeptical that you have much clay at all. We live on limestone deposits over 1,000 feet deep; however, every now and then there is a pocket of clay, so the chances are you have limestone that is acting like clay due to the amount of magnesium in it. In any case softening the soil is much easier done than by rototilling. Rototillers are for veggie gardens, not for lawns - and I would argue that they are more damaging than helpful for veggie gardens, too. But for a lawn, they really, REALLY cost you in the long run.

There are only two kinds of grass that grow easily in Austin. Those are St Augustine (no seed for St Augustine) and bermuda (tons of seed available). If you tried planting a northern grass like fescue or Kentucky bluegrass, and you did it in the past few weeks, it should have sprouted and looked good. If you tried to plant bermuda in the past few weeks, it should look sparse and awful.

What was your watering regimen for the new seed? It should have been about 5 minutes, 3x per day, for the first 3 weeks. The idea at first is to keep the surface of the soil moist all the time. Then you should have had about 80% germination unless you planted bermuda. If you planted bermuda recently I would expect maybe 10 to 20% germination. Bermuda needs to be seeded in June and July here in Central Texas. Cooler temps prevent it from germinating.

Answer the questions and maybe we can recover from this.

>> If you read Neil Sperry in the paper, just do the opposite of what he says. I don't know where that guy lives, but it's not on my planet.

I love this. Ignore most--if not quite all--of the lawn advice columns you read. I'm not sure where they're getting their information, but it contradicts even books written in the 1930's.

"We live on limestone deposits over 1,000 feet deep; however, every now and then there is a pocket of clay, so the chances are you have limestone that is acting like clay due to the amount of magnesium in it. "

Limestone is a rock. http://geology.com/rocks/limestone.shtml

Limestone, in itself, will not grow any thing, nor will you be able to do much with it with a rototiller.

If you have questions about your soil I would suggest that you go down to the county agricultural office and ask them your questions.

It is difficult to asses what kind of soil you have. Soils can be significantly different a mile away from your house. In my area I have a dense clay soil, that is full of quartz rock. About a mile away, the soil is nearly pure sand.

Also your lot can be different than the lot next door. Did they remove the topsoil in grading the lot to make it suitable for building? Did they do a lot of fill to build the lot up to build? We lived in a new addition and watch them fill a hole with about 15 feet of dirt and build on it. I am sure that lot's soil was different than mine.