- A plant's basic needs are sunlight and water. But a plant also needs nutrients from the soil in which it grows in order to be healthy, continue creating cells and eventually produce flowers or fruit. Though the specific requirements vary from plant to plant, every plant needs these nutrients in some amount: nitrogen, phosphorus, potassium, calcium, magnesium, sulphur, iron, manganese, zinc, boron, copper and molybdenum.
- As plants grow in soil, the soil loses the nutrients to the growing plants. Some plants return nutrients to the soil, while others demand high amounts of nutrients. If one piece of land is used for the same type of plant over and over, it will become deficient in the nutrients used most by that particular plant. Adding soil amendments is one way to restore nutrients to deficient soil. Some soil amendments will provide one or two particular nutrients; lime, for example, provides calcium and magnesium to the soil. Other soil amendments, such as fertilizer blends, provide a broader combination of nutrients to the soil.
- The pH balance of the soil is also important to healthy plant growth. Some plants require a more alkaline environment; some need a more acidic soil in which to grow. By testing the soil to determine the pH and then comparing that to the pH requirements of the plants you wish to grow, you can determine what soil amendments to add in order to bring the soil to the right pH level.
