This self-contained kit will enable you and your students to quickly assess soil pH and the relative amount of three key elements—nitrogen, phosphorus and potassium (potash). Tests are as simple as dropping the contents of a capsule into the sample and comparing the resulting color to a set of standards. The remarkably extensive instructions detail how to conduct the tests, when to conduct the tests, preferred pH ranges for hundreds of plants and how to select and apply the proper fertilizers. Each test can be conducted 10 times. A refill kit containing an additional 10 capsules for each of the four tests is offered separately.