On what basics plant elements are divided into macronutrients and micronutrietns?

Answer

### Step-by-Step Solution:

1. **Definition of Macronutrients and Micronutrients**:
- Plant nutrients are classified into two categories: macronutrients and micronutrients.

2. **Basis of Classification**:
- The classification is based on the relative concentration of these nutrients in the plant's dry matter.

3. **Concentration Threshold**:
- Nutrients are categorized as macronutrients if their concentration is greater than 10 millimoles per kg of dry matter.
- Conversely, if the concentration is less than 10 millimoles per kg of dry matter, the nutrients are classified as micronutrients.

4. **Examples of Macronutrients**:
- The primary macronutrients include:
- Carbon (C)
- Hydrogen (H)
- Oxygen (O)
- Nitrogen (N)
- Phosphorus (P)
- Sulfur (S)
- Potassium (K)
- Calcium (Ca)
- Magnesium (Mg)

5. **Examples of Micronutrients**:
- The primary micronutrients include:
- Iron (Fe)
- Manganese (Mn)
- Zinc (Zn)
- Copper (Cu)
- Molybdenum (Mo)
- Boron (B)
- Chlorine (Cl)
- Nickel (Ni)

### Summary:
Plant elements are divided into macronutrients and micronutrients based on their relative concentration in the plant's dry matter, with a threshold of 10 millimoles per kg distinguishing the two categories.

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