I'm just gonna keep posting. I was reading around finding info on proper Calcium to Magnesium levels. I've found that Calcium should be higher in ratio to Magnesium. Googling led me to a paragraph- "High magnesium soils can prove to be a challenge if crop rotation, manure additions and timely tillage operations are not followed. Moderate rates of K applications are needed when potash is low to medium. Additions of gypsum are proclaimed to loosen the soil; however this is only part of the solution. The additions of organic matter to provide the necessary biological activity to promote strong soil aggregate stability is if more importance. " This fits with my low organic matter, and high magnesium. However, I feel the reduction of Magnesium in the lawn would be tough to tackle. Boosting Calcium would probably be easier but I worry about over shooting.

quirky, don't lose faith yet. About 1/8th of my current lawn was common bermuda grass 2 years ago that spread from my neighbor's lawn. It's all bluegrass today, and since the roundup attack of 2 years ago, not one bermuda has returned. The lawn was sprayed by a Landscaping company, then after it died, I completely destroyed the roots system with a roto tiller. I wish I would have taken pictures of it them, because I know that seeing is believing. Having said that, I constantly have to patrol the areas adjacent to my neighbor's bermuda lawn. To matters worst, my neighbor is the type of guy that will let his bermuda grow to about 4 inches tall, seeds out like son of gun because it's a commong type, then chops it down to an inch leaving bermuda sticks and dirt. Then a couple of weeks later the cycle repeats. I have a plan, next spring when the bermuda starts to come out of dormancy, I'm going to spray Turflon at night to make sure stays a sleep a little longer:-)

What about white clover? The only downside I see to using mulch as suggested previously is that mulch will continually need to be replaced. This may be a problem for some. I would guess a living mulch such as clover would take care of itself.

Seed underneath the sod will be smothered and never grow ! Fescue and Bermuda are a bad mix , because they have completely different growth habits. If it was me, I would go with Bermuda sod "wall to wall" with no Fescue, and over seed the shady areas with Zoysia next summer. There is not enough heat left right now- to get Zoysia established before the cold sets in , so you have to wait til late spring/ early summer....... Zoysia is slow to establish, but lots of heat over a long summer-helps speed things up ! Before seeding the Zoysia into Bermuda, you would mow short- so the seeds can fall close to the soil line. Raking the area after seeding, would further move the seed down ward.