Testing soil pH and fertility

Before putting money into lawn fertilizer, I had to check the pH and fertility of the soil.

I bought this tester and several disposable testers. I did multiple tests on one part of the lawn to benchmark the tester. Once I knew it was testing right, I checked different parts of the lawn.

The pH throughout the yard is fine, but I need to improve fertility. I’ll probably buy a balanced fertilizer and some weed killer.