Its vital to know the existing pH, Nitrogen (N), Phosphorous and Potash (K) levels in garden soil. The rapitest Soil Test Kit continues to be the standard for home soil testing. The kit includes all components needed to for (40) tests: (10) each for pH, Nitrogen, Phosphorus and Potash. The patented color comparator system allows for easy color comparisons versus a typical printed color chart. Extensive, yet simple, instructions are included along with recommendations for over 400 plants.