Start with a good, reliable soil test. Your states university may offer that through the Cooperative Extension Service. You need to know what the soils pH is and if it needs correction and with what. You also should know the amount of organic matter in the soil because that is what the Soil Food Web needs to live on and soil organic matter aids in holding nutrients in the soil as well as moisture.
Composted Poultry manure could be of some help in getting started, just understand that it can take some time to correct years of mistreatment. Mulch mowing, recycling the grass clippings can also help since those grass clippings can supply up to 1/2 the Nitrogen grass needs annually to grow. Mulch mowing the leaves from any deciduous trees back into the soil also will help by adding more organic matter. Perhaps, along with that soil test for pH and nutrients1) Structure. From that soil sample put enough of the rest to make a 4 inch level in a clear 1 quart jar, with a tight fitting lid. Fill that jar with water and replace the lid, tightly. Shake the jar vigorously and then let it stand for 24 hours. Your soil will settle out according to soil particle size and weight. A good loam will have about 1-3/4 inch (about 45%) of sand on the bottom. about 1 inch (about 25%) of silt next, about 1 inch (25%) of clay above that, and about 1/4 inch (about 5%) of organic matter on the top.

2) Drainage. Dig a hole 1 foot square and 1 foot deep and fill that with water. After that water drains away refill the hole with more water and time how long it takes that to drain away. Anything less than 2 hours and your soil drains� too quickly and needs more organic matter to slow that drainage down. Anything over 6 hours and the soil drains too slowly and needs lots of organic matter to speed it up.

3) Tilth. Take a handful of your slightly damp soil and squeeze it tightly. When the pressure is released the soil should hold together in that clump, but when poked with a finger that clump should fall apart.

4) Smell. What does your soil smell like? A pleasant, rich earthy odor? Putrid, offensive, repugnant odor? The more organic matter in your soil the more active the soil bacteria will be and the nicer your soil will smell.

5) Life. How many earthworms per shovel full were there? 5 or more indicates a pretty healthy soil. Fewer than 5, according to the Natural Resources Conservation Service, indicates a soil that is not healthy.
these simple soil tests can be of some use.

Thank you for the reply, I will start with the soil test and your other recommendations.

In the mean time, I walked the grass last night and observed a lot of leaf spot and red thread so I'm thinking of starting with corn meal.

Your thoughts?

A study from Texas A & M seemed to point to corn meal as a fungicide but research by others did not get the results reported by the TAMU researchers and they could not replicate the initial results. A large number of people seem to be convinced corn meal works even though there is nothing to support that.

Welcome to organic lawn care (not the forum but the concept)! We'll need a little more information about your situation but a lot of modern theory behind it applies almost universally.

Compost is not the ultimate solution anymore. It never was but nobody knew any better. King Compost was the idea of Rodale and those who followed him up until the early 2000s. In the 1990s there was DNA research on the soil that revealed the secret to why organic fertilizer worked and compost had only limited value. The secret is microbes - tens of thousands of them. Prior to that revelation it was believed there might have been tens of microbes living in the soil. Tens of thousands opened up so many concepts of interdependent food chains that the global food chain in the soil was named the soil food web. It is the soil food web that creates plant food, plant medicines, vitamins, minerals, enzymes, and really everything that happens inside the gut of a higher order species of animals. Then the solution to making organic gardening work became food instead of compost. Compost has no food value left in it. Food is all food. The food that we use is made from cereal grain sources and other nuts, beans, and plant materials high in protein. If you look at a bag of commercially bagged organic fertilizer you'll see corn, wheat, alfalfa, soy, flax, cottonseed, feather meal, and some animal byproducts. Commercially bagged fertilizer costs about $0.65 per pound in quantity. However, if you visit your local feed store you'll find the same materials in 50-pound sacks for something like $0.30 per pound. The cost used to be more like $0.06 per pound but that is certainly changing. In any case what most of us do is buy bagged alfalfa pellets or soy bean meal at the feed store. The application rate is 20 pounds per 1,000 to start. You can go up to 50 or 60 pounds per thousand if you have the budget for it. Most don't.

Red thread and rust are two fungal diseases that will not be touched by corn meal. I've never had those but I have been reading this and other forums for about 10 years and that is the combined intelligence from the readers here. For other fungal diseases, as kimmsr said a large number of readers/writers here have had success with ordinary corn meal applied at 20 pounds per 1,000 square feet to eradicate an existing disease. Having said that, many also report that it has not worked for them. What I know is that I would not have a lawn at all were it not for corn meal. I'm a strong advocate for it, but not for red thread or rust.

Your soil is not sterile. It is unfed. As soon as you feed it with real feed, it will respond with an unbelievable flush or dark green growth. I'll post a picture to show an example.

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This photo was posted almost a year ago here on Gardenweb. It is mrmumbles zoysia lawn. He applied alfalfa pellets in May and took the picture in June. As I recall there was no compost involved. His story was similar to yours - years of chemicals and a switch to organics. I believe this was a test. Many people are skeptical and do a similar test using dry dog food (a great source of protein). Most do not post the pictures, though.