📖 Lesson 7: Organic and Inorganic Fertilizers

👩🏽‍🏫 Introduction

Hi again, grower of green things! 🌾🌻

In the last lesson, you learned that soil nutrients are essential for plant health. But how do we add those nutrients back into the soil when they run low?

That’s where fertilizers come in. In this lesson, we’ll explore the two main types: organic and inorganic fertilizers. You’ll learn their differences, benefits, limitations, and the best ways to apply them.

By the end of this lesson, you’ll be ready to make smart choices about nourishing the soil for better crop yields!

📘 Core Concepts

🔹 What Are Fertilizers?

A fertilizer is any material added to soil to supply nutrients that plants need to grow. Fertilizers improve:

• Soil fertility

• Plant growth

• Crop yield

🔹 Types of Fertilizers

Fertilizers are grouped into organic and inorganic (chemical) types.

1. Organic Fertilizers 🌿

Made from natural plant or animal matter.

✅ Examples:

• Compost (rotted plant/food waste)

• Farmyard manure (cow dung, poultry droppings)

• Green manure (fresh plant material)

• Bone meal and fish meal

🌱 Advantages:

• Improve soil structure and water retention

• Release nutrients slowly and steadily

• Environmentally friendly (biodegradable)

• Encourage microorganisms in the soil

⚠️ Limitations:

• Work slowly

• May have lower nutrient levels

• Bulky to transport and apply

• Need time to decompose

2. Inorganic Fertilizers ⚗️

Made from chemicals or minerals, often in factories.

✅ Examples:

• NPK fertilizer – contains Nitrogen (N), Phosphorus (P), Potassium (K)

• Urea – rich in nitrogen

• Superphosphate – high in phosphorus

• Ammonium nitrate – nitrogen source

• Potassium chloride – supplies potassium

🌱 Advantages:

• Nutrients are concentrated and act fast

• Easy to transport and apply

• Precise nutrient content

⚠️ Limitations:

• Can damage soil if overused (soil acidity)

• Don’t improve soil structure

• Risk of leaching (nutrients washed away)

• May harm the environment

🔄 Comparison Table

🔧 Methods of Applying Fertilizers

🧠 Choose the method based on the crop, soil condition, and type of fertilizer.

🧩 Sample Problem Walkthrough

🧠 Problem:
A farmer wants to improve the nutrient content of their farm without harming the soil. They also want to promote long-term soil fertility. Which type of fertilizer should they use, and why?

✅ Step-by-Step Solution:

• For long-term soil health and natural improvement, organic fertilizers are better.

• Compost or manure will add nutrients and improve soil structure.

✔️ Answer: The farmer should use organic fertilizer because it improves soil structure and provides long-term fertility without harming the environment.

✍🏽 Practice Exercises

1. Fill in the blanks

(a) NPK fertilizer is an example of an _______ fertilizer.
(b) Compost is made from _______ materials.
(c) One method of applying fertilizer beside plants is called _______ dressing.

Answers:
(a) inorganic
(b) organic
(c) side

2. Match the Fertilizer to Its Source

Answers:
(i) → B, (ii) → A, (iii) → C

3. Short Answer

Q: Give one advantage and one disadvantage of using inorganic fertilizer.

Sample Answer:
Advantage: It provides nutrients quickly.
Disadvantage: Overuse can damage the soil and pollute the environment.

🌀 Recap

Here’s what we’ve learned:

• Fertilizers supply nutrients to support plant growth.

• Organic fertilizers are natural, eco-friendly, and improve soil health.

• Inorganic fertilizers act fast and are nutrient-rich but can damage the soil if misused.

• Different application methods are used based on crop and soil conditions.

💭 Reflection Prompt

You are advising a friend who wants to start a small farm.
Would you recommend organic or inorganic fertilizers—or both?
Explain your choice with two reasons.