Question
We have been in our home for 11 years.  We are constantly needing to seed our back yard.  It looks really good for awhile and then it starts to die off.  We put a sprinkler system in 2 years ago thinking that maybe the yard needed more water.  We also have a hedge row of trees along the back side of the yard which we have wondered at times if they could be the problem.  About 1 month ago we had a lawn service company take a soil sample and they sent it away to be analyzed.  They called today and stated that the soil is very high in phosphorus, "over 200" and high in potassium, "800 or so."  They stated that since the phosphorus and potassium are so high, they are not sure what will need to be done and they will get back with us.  Why would the soil be so high in phosphorus and potassium  and what do you think that we need to do?  We have fescue planted in the yard now.  We live in Olathe, Kansas in the city.  

Answer
The high potassium and phosphorus would likely be from fertilizers with high P and K percentages being applied over the years. At this point, I'd recommend adding some topsoil to the property to dilute the amount of P and K. Just spread a few inches in top and mix it down into the top few inches of existing soil. You can then re-seed or sod.

-Good luck!