Lived in house 23 yrs. Lawn great last 10 years but this year brown patches front and back. Property is 1/3 acre including house. Suspect neighbors did something but maybe fungus. Applied fungus control after scraping off all loose soil and grass. Can you recommend local soil testing lab to check regular nutrients but also foreign substances ie gasoline and other poisons?
There has been a lot of brown patch fungal disease in lawns this year. The good news about this fungal disease is that the roots usually survive and put out new growth in the fall. Early fall is the premier time to overseed if that is necessary.
Be sure not to fertilize in early spring. The resulting overly weak lush growth is an invitation to fungi.
Here's info on managing brown patch: https://extension.umd.edu/hgic/topics/brown-patch-lawns
Soil testing for anything except the usual range of nutrients (including lead, etc.) is extremely expensive. You would have to identify the chemical that you want the laboratory to locate. You can't just say to look for detrimental chemicals in general.
Here is our page on soil testing, which includes how a video on how to collect the sample and what to test for. https://extension.umd.edu/hgic/topics/soil-testing We'd lean toward using the University of Delaware lab.