I bought a cheap two-prong meter from a local hardware store, but the needle barely moves regardless of where I stick it in my yard. Do soil ph tester really work, or are these inexpensive analog devices notoriously inaccurate compared to liquid test kits or professional lab analysis? My blueberries are looking a bit yellow, which suggests an alkalinity issue, but I’m hesitant to add sulfur based on a reading from a tool that might be faulty.