The rapitest Soil Test Kit continues to be the standard for home soil testing, allowing you to know the existing pH, Nitrogen (N), Phosphorous (P) and Potash (K) levels in garden soil. 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. Instructions are included along with recommendations for over 400 plants. Test results allow the gardener to amend and fertilize appropriately.