Sounds like you are on the right track. You've put down some great amendments but might be missing a vital link - microbe health. The dried cow manure may have been quite rich and a little hot so you could get some yellowing from that but it shouldn't be too much. Best to use well composted material whether it is plant derived or manure derived.
How's your soil life other than no grubs? Do you see any earthworms? Do you see any other small soil creatures? These tell a story. They will be present where there is nourishment for their life cycle and if they are missing, it's an indicator of low soil life.
Let me suggest you apply molasses, dry or liquid, to boost the microbial activity. Good microbe life is essential to allow your plants, turf and trees to utilize the nutrients you have in your soil. It is inexpensive and usually quite effective in clay soil. It's also a good buffer if the manure was too hot. I have friends who got grass to grow beautifully in places where it hadn't grown in years with just the addition of molasses. And the best part of all is that it will be beneficial no matter what the root problem is with the soil.
A compost tea (easier) or compost in a 1" layer will add more organic material to the soil and a new population of microbes to do the work if your soil is deficient in soil life. That's another relatively inexpensive remedy.
The right moisture level is also important. What is your watering schedule? Do you water deeply less often or are you still on the two or three times a week for 20 minutes program? These make a difference too.
Hopefully these suggestions will help you to remedy your problem. Keep trying, keep thinking...and Never give up. You will not regret it.
Hope that helps! Please let us know.
Kathe
No reason to allow the peat to go to waste.
