RapiTest Soil Test Kit pH/N-P-KCheck your soil for pH, and the macronutrients plants need: Nitrogen, Phosphorus, and Potassium. If you are new to soil testing you will appreciate this fast, easy and fun way to achieve better growing results from your gardening efforts. Mix soil sample with water, transfer some of the solution to the color comparator, add powder from the capsule, shake and watch the color develop. Note your test results in a few minutes. Patented design Everything