It provides you with an economical way to rapidly test the PH as well as the three basic elements needed for a healthier plant: Nitrogen, phosphorus and Potassium.
PH soil can be acid, neutral or alkaline. Each plant has a range of PH in which it thrives and most plants prefer conditions near the neutral mark (PH 5.5 - 7.5). There are however plants that prefer acid or alkaline enviroments. The solubility of the nutrients, that is the ability of the plants to absort them, depends largely on their PH value. The soil microbiological activity is also PH dependent. Most bacteria, specially those putting nutrients at the plants disposition, prefer moderately acid or slightly alkaline conditions. The PH level hence influences the fertility of the soil.