From amleo.com
This Electronic Soil Analyzer measures four components vital for plant growth. This single meter measures pH, fertility, moisture, and light levels. It features an easy-to-read face for precise results. The included plant guide gives you recommendations for most types of plants.
The Electronic 4-Way Soil Analyzer Meter is easy to use. First, select your desired measurement. Next, remove the top two inches of soil and break up the ground underneath to a depth of 5 inches. Thoroughly wet the soil with water and insert the probes into the soil to within 1 inch of the housing unit. Allow the meter to stabilize and then record your results. Finish by removing the probe and wiping it clean.
This meter displays pH readings of 1 to 9. Fertility reads as “too little”, “ideal”, or “too much” based on USDA standards for combined soil N-P-K levels. It measures soil moisture and gives you a result of 1 to 4 (dry to wet) and displays light measurements of 0 to 10,000 foot-candle hours.