jb wrote:
I removed a large pine tree in my yard. The circle diameter in the
ground is close to 10ft. The tree was 20 years old. How do I treat the
underlying soil to make it ready for grass planting. Thanks for your help

The standard answer is "don't guess - get a soil test".
However, in practice, an educated guess would be 15 lbs of lime spread
over a 20' circle and worked into the soil. (lime placed on the surface
penetrates average soil 1"/yr.)

Bob S.