Luster Leaf Rapitest Soil Test Kit is an innovative and inexpensive way to test a number of soil conditions using an easy capsule system and unique color comparators. Simple, fast and accurate, these tests can be used without any experience required. The Rapitest soil kit contains 40 tests, including 10 for each of pH, nitrogen, phosphorus and potassium levels. Simply mix the soil with water, then drain out as much water as possible. Next, dissolve a test capsule from the Luster Leaf Soil Test Kit and compare the color to the handy, easy-to-understand included chart. The chart includes pH and NPK levels for more than 100 plants. It also includes complete instructions for adjusting soil conditions and fertilization.