A soil's ability to supply mineral nutrients, chemicals other than carbon, hydrogen, and oxygen, is the principal factor in its fertility. Essential elements are those that are required for the growth of healthy plants.
- Macronutrients are elements required in relatively large amounts.
- Micronutrients, or trace elements, are needed only in minute amounts. Despite the small amounts needed, the requirement for most micronutrients is just as absolute as for macronutrients.
| Element |
Concentration
(relative units) |
Role within the plant |
| Macronutrients |
| Nitrogen |
|
formation of proteins & nucleic acid |
| Potassium |
|
formation of enzymes |
| Caclium |
|
proper functioning of cell membraines |
| Phosphorus |
|
formation of nucleic acids and ATP |
| Sulfur |
|
formation of proteins, coenzymes for carbohydrate metabolism |
| Micronutrients |
| Iron |
|
essential for chlorophyll synthesis |
| Boron |
|
formation of cell wall in meristems |
| Manganese |
|
formation of oxygen in photosynthesis |
| Zinc |
|
cell respiration and nitrogen metabolism |
| Copper |
|
Formation of enzymes used in respiration and photosynthesis |
Due to the frequently marginal supply of, and competition for, nutrient elements in nature, it is important for plants to reuse essential nutrients. When a leaf grows old it turns yellow, reflecting the breakdown of chlorophyll as well as most of the leaf protein. Most of the nitrogen from these compounds is recovered by plants before the leaf is shed. The export of nutrients from leaves occurs in the phloem. The recovered nutrients are stored in the stem or roots of the plant for use in the next year's spring growth.
|