Introduction: Just like animals, plants need nutrients in order to grow and reproduce. But unlike a bird or a whale that can hunt for their food and then eat it to get the nutrients they need, plants must get their nutrients mostly from the soil and the air. The main nutrients they need (and all living things need, for that matter) include carbon, hydrogen, nitrogen, oxygen, phosphorus, and sulfur (CHNOPS is used to remember these). In addition, calcium and magnesium are important, but not in as great quantities.
Nitrogen is probably the most important nutrient a plant needs. They take this in through the roots from the soil. Nitrogen is used for:
- building protein and enzymes
- rapid growth, increasing fruit and seed production
- making leaves larger
- photosynthesis by being part of chlorophyll
Nitrogen enters the plant from fertilizers being added to the soil and from the atmosphere through a process called nitrogen fixation. Here, some plants have symbiotic bacteria living on their roots that pull atmospheric nitrogen out of the air and convert it into a form the plants can use. Nitrogen is one of the biogeochemical cycles that move nutrients around the earth. The image below shows how this happens.
Phosphorus is also a very important nutrient for plants. It:
- is part of photosynthesis
- causes roots to grow and flowers to bloom
- assists with the production of energy
Phosphorus is also a part of fertilizers.
Calcium is a part of the plant cell wall and strength to the plant cell.
Magnesium is part of the chlorophyll molecule (which is important for photosynthesis) and activates many plant enzymes used for growth and metabolism.
- needed to create proteins for the plant
- helps to create vitamins
- assists with chlorophyll formation
- increases root growth
- protects plants from the cold.
Sulfur can be found in rainwater and enters the soil from precipitation.
Carbon and Hydrogen are incorporated into a plant through the process of photosynthesis. Remember, plants take in carbon dioxide and water and with the energy provided by sunlight, convert them into glucose and oxygen. Plants then use cellular respiration to break down the glucose into its chemical elements.
Directions for this Lesson: Answer the practice questions and then watch the video to learn more about how plants maintain their metabolisms.