Back to: Botany 200 Level
Hello, my brilliant student! How are you today? Have you ever wondered why farmers add fertilisers to their crops or why plants look weak and yellowish when they lack certain nutrients? Just like humans need food to stay healthy, plants need essential nutrients for growth, development, and survival. Today, we’ll learn about plant nutrients, how they are classified, and why they are important.
Essential nutrients and their classification (macronutrients vs. micronutrients)
Plants require certain chemical elements to grow properly. These elements are called essential nutrients because they help in important functions like photosynthesis, cell division, and water movement. Without these nutrients, plants become weak, discoloured, or even die.
Plant nutrients are classified into two main categories:
Macronutrients – Needed in large amounts.
Micronutrients – Needed in small amounts but still essential.
Macronutrients: The Major Nutrients
Macronutrients are required in large quantities because they are directly involved in the plant’s major functions. They include:
Nitrogen (N) – Helps in making proteins, chlorophyll, and leaves.
Deficiency symptoms: Yellowing of leaves (chlorosis), stunted growth.
Source: Fertilisers, organic matter, and compost.
Phosphorus (P) – Supports root growth, flowering, and energy transfer (ATP).
Deficiency symptoms: Poor root development, delayed flowering, purplish leaves.
Source: Bone meal, rock phosphate, and fertilisers.
Potassium (K) – Helps in water regulation, disease resistance, and fruit formation.
Deficiency symptoms: Weak stems, brown leaf edges, poor fruit development.
Source: Wood ash, compost, potash fertilisers.
Calcium (Ca) – Strengthens cell walls and supports root and leaf growth.
Deficiency symptoms: Deformed leaves, weak stems, poor root development.
Source: Lime, gypsum, eggshells.
Magnesium (Mg) – The main component of chlorophyll, needed for photosynthesis.
Deficiency symptoms: Yellowing between leaf veins.
Source: Dolomite, Epsom salt, magnesium sulphate.
Sulphur (S) – Helps in making proteins and enzymes.
Deficiency symptoms: Yellowing of younger leaves, stunted growth.
Source: Organic manure, gypsum.
Micronutrients: The Small but Mighty Nutrients
Micronutrients are needed in tiny amounts, but they are still very important. They include:
Iron (Fe) – Helps in making chlorophyll and energy production.
Deficiency symptoms: Yellowing between veins of young leaves.
Source: Soil minerals, iron chelates.
Manganese (Mn) – Helps in photosynthesis and enzyme activation.
Deficiency symptoms: Light green leaves with dark veins.
Source: Organic matter, manganese sulphate.
Zinc (Zn) – Supports hormone production and leaf growth.
Deficiency symptoms: Small leaves, short stems.
Source: Zinc sulphate, compost.
Copper (Cu) – Helps in enzyme activity and seed production.
Deficiency symptoms: Wilting, twisted leaves.
Source: Organic matter, copper sulphate.
Boron (B) – Supports flowering, fruit formation, and cell wall strength.
Deficiency symptoms: Poor fruit and seed development.
Source: Borax, compost.
Molybdenum (Mo) – Helps in nitrogen metabolism.
Deficiency symptoms: Yellowing leaves, poor nitrogen absorption.
Source: Soil minerals, molybdenum fertilisers.
Chlorine (Cl) – Supports photosynthesis and disease resistance.
Deficiency symptoms: Wilting, poor growth.
Source: Rainwater, soil minerals.
Summary
Macronutrients are needed in large amounts (e.g., Nitrogen, Phosphorus, Potassium, Calcium, Magnesium, Sulphur).
Micronutrients are needed in small amounts but are still essential (e.g., Iron, Zinc, Manganese, Copper, Boron, Molybdenum, Chlorine).
Each nutrient has specific roles in plant growth, and their deficiency leads to visible symptoms like yellowing, stunted growth, or poor flowering.
Evaluation
- What is the difference between macronutrients and micronutrients?
- Why is nitrogen important for plants?
- What happens when a plant lacks potassium?
- Name two micronutrients and their functions.
- What is the role of phosphorus in plants?
Fantastic work! Now you understand why plants need different nutrients to grow, stay healthy, and produce food. Keep up the great learning spirit—Afrilearn is here to make learning easy and fun! See you in the next lesson!
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