First, to understand the chemistry of fertilizers, it is necessary to have a basic knowledge of the chemistry of plants. Plants need quantities of certain chemicals in order to function, just like humans do. The point of a fertilizer is to supply the plants with those needed nutrients in order to make the plant healthier than it would be otherwise. In general, the idea of a fertilizer is to enrich the soil with nitrogen, phosphorus, and potassium; the three major nutrients required by plants. The type of fertilizer necessary is dependent on the plant being grown. Different plants require vastly different ratios of these three ingredients. This is the theory behind crop rotation by farmers. A cycle of different plants can maximize the efficiency of growing crops. Nutrient-poor soil is sometimes referred to as tired soil. In general, adding too much fertilizer will acidify the soil and kill plants trying to grow in it. Soil fertility assessment is an important goal of soil chemistry and waste management. Soil fertility was maintained by manure application and crop rotation at that time the reasons for effective nutrient uptake were not properly understood. In this paper the chemical processes in soils which affect soil formation, soil fertility and nutrient supply will be discussed with emphasis on the environmental context.