Fertilizers, Manure & Plant Nutrition

Grade 7 · General Science

Semester 2 | Period 6 | Week 34

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Subject: General Science

Semester: 2

Period: 6

Week: 34

School Name:
Teacher’s Name:
Subject: General Science
Grade Level: Grade 7
Date:
Week & Period: Week 34, Period 6
Lesson Duration: 45 minutes
Topic: Fertilizers, Manure & Plant Nutrition
Sub-topic: Types, Importance, and Effects of Fertilizers and Manure

 

Learning Objectives

By the end of the lesson, students should be able to:

  1. Differentiate between manure and fertilizer.
  2. Identify types of fertilizers (organic and inorganic).
  3. Explain the importance of fertilizers in plant growth.
  4. Discuss the effects of overusing fertilizers.
  5. Relate the use of compost and fertilizers to the Liberian context.

 

Previous Knowledge

Students already know from previous lessons that plants need nutrients from the soil to grow.

 

Instructional Materials

  • Samples/pictures of compost (manure) and chemical fertilizer bags (NPK, urea, etc.)
  • Chart showing plant growth with and without fertilizer
  • Chalkboard, markers, and textbooks

Lesson Development – ABC Model

A – Anticipation (Warm-up / Starter)

Time: 5–7 minutes
Activity: Teacher shows learners a small maize plant grown in poor soil and another grown in fertile soil with manure/fertilizer.
Questions:

  • Why do you think one plant looks healthier than the other?
  • How do farmers help weak soil produce more food?

Learners’ Role: Observe and respond.
Teacher’s Role: Guide and record answers.

 

B – Building Knowledge (Main Lesson Body)

Time: 25–30 minutes

 

Teacher’s Role (Expanded Explanation & Demonstration)

  1. Difference between Manure and Fertilizer
  • Begin with a simple question: “What do farmers add to soil so that crops can grow well?”
  • Guide learners to see the difference:
    • Manure → Natural, made from decomposed animal waste, crop residues, or compost. It improves soil structure and fertility gradually.
    • Fertilizer → Any material added to soil to supply nutrients. Can be organic (natural) or inorganic (chemical). Fertilizers act faster than manure.
  • Demonstrate by showing a handful of compost (manure) and a packet of NPK fertilizer.
  1. Types of Fertilizers (Explained with Examples)
  • Organic Fertilizers (Natural):
    • Examples: compost, cow dung, poultry droppings, green manure, crop residues.
    • Characteristics: release nutrients slowly, improve soil texture, environmentally friendly.
  • Inorganic Fertilizers (Chemical/Man-made):
    • Examples: NPK (Nitrogen, Phosphorus, Potassium), Urea, Ammonium sulfate.
    • Characteristics: supply nutrients quickly, easy to apply, but can damage soil if overused.
  • Teacher explains that both can be used together in integrated farming.

 

  1. Importance of Fertilizers in Plant Growth (Well-Detailed)
  • Improve soil fertility → replace nutrients taken by crops.
  • Supply essential nutrients →
    • Nitrogen (N) → helps in leafy growth (e.g., cassava leaves, maize leaves).
    • Phosphorus (P) → helps in root development and flowering.
    • Potassium (K) → strengthens stems, improves fruiting and disease resistance.
  • Increase crop yield → more harvest of rice, maize, vegetables, cassava.
  • Faster growth and healthier plants → ensures food security.
    (Teacher can use charts or illustrations showing stunted vs. healthy plants with fertilizer.)
  1. Effects of Overuse of Fertilizers (Explained with Context)
  • Soil pollution → chemicals build up and reduce soil quality.
  • Water pollution → excess fertilizer washed into rivers, streams, and wells → causes algal bloom, kills fish, makes water unsafe.
  • Damage to soil structure → soil becomes hard, less able to retain water.
  • Reduced long-term fertility → soil loses natural nutrients and depends only on chemicals.
  • Harm to humans → crops may carry chemical residue that affects health.
    (Teacher can give a real example: Some Liberian farmers who overuse fertilizer on rice fields end up with poor yields in the following seasons.)

 

  1. Relation to Liberia (Local Context)
  • Many rural farmers rely on compost, cow dung, and poultry droppings because they are cheap and available.
  • Imported fertilizers like NPK and urea are used for crops such as rice, cocoa, coffee, rubber, oil palm, and vegetables.
  • Government and NGOs sometimes support farmers with subsidized fertilizers, but misuse or lack of training can lead to problems.

 

Learners’ Activities (Expanded & Interactive)

  • Practical Comparison: Learners examine real samples of compost and chemical fertilizer (NPK) and note differences in appearance, smell, and texture.
  • Group Work: In groups, learners list advantages and disadvantages of organic vs. inorganic fertilizers on chart paper.
  • Community Connection: Learners share what farmers in their town or village use (e.g., cassava farms with compost, rice farms with NPK).
  • Class Debate: “Which is better for Liberia—organic manure or inorganic fertilizer?” Groups present their arguments.
  • Role-play: Learners act as farmers explaining to others why they choose manure or fertilizer.

 

Assessment Checks (Oral & Written)

  • Oral Questions:
  1. What is the difference between manure and fertilizer?
  2. Give one example each of organic and inorganic fertilizer.
  3. Why is fertilizer important for plants?
  4. What are two dangers of using too much fertilizer?
  • Quick Written Exercise:
    • Fill in the blanks: __________ is natural and comes from animals or plants.
    • True/False: NPK is an organic fertilizer.
    • List three nutrients in NPK and state their functions.

 

Notes (Expanded & Detailed)

  • Fertilizers are materials added to soil to improve fertility.
  • Manure is natural (animal droppings, compost, green manure).
  • Fertilizers can be organic (natural) or inorganic (chemical, like NPK, urea).
  • Importance: improve soil fertility, supply nutrients (N, P, K), increase crop yield, promote healthy growth.
  • Overuse causes soil and water pollution, weakens soil structure, reduces long-term fertility, and may harm human health.
  • In Liberia, farmers use both compost (manure) and chemical fertilizers for crops like rice, cocoa, and vegetables.

 

Extended Assignments (Homework)

  1. Write the differences between manure and fertilizer in a table.
  2. List two examples of organic fertilizers and two of inorganic fertilizers.
  3. Explain why nitrogen, phosphorus, and potassium are important for plants.
  4. Interview a farmer in your community to ask which type of fertilizer they use and why.
  5. Draw and label a diagram showing the effects of too much fertilizer on soil and water.

 

C – Consolidation (Conclusion & Assessment)

Time: 5–8 minutes

Summary (Teacher & Learners):

  • Manure vs Fertilizer.
  • Types of fertilizers.
  • Importance of fertilizers.
  • Effects of overuse.
  • Liberia’s use of fertilizers and compost.

Evaluation Questions (Quick Quiz):

  1. Define fertilizer.
  2. State two differences between manure and fertilizer.
  3. Give two examples of organic fertilizers.
  4. Give two examples of inorganic fertilizers.
  5. Mention two negative effects of overusing fertilizers.

 

Assignment

  • Write 6 sentences on the importance of manure for farmers in your community.
  • Draw a table showing two differences between organic and inorganic fertilizers.

 

Differentiation / Inclusive Strategies

  • Struggling Learners: Use real-life objects (compost heap, empty fertilizer bags) for easier understanding.
  • Advanced Learners: Research other modern methods of improving soil fertility (bio-fertilizers, crop rotation).
  • Students with Disabilities: Provide pictorial aids and simple definitions.

 

Teacher’s Reflection (After Class)

  • What worked well? ___________________________________
  • What needs improvement? ____________________________
  • Students’ engagement level: □ High □ Medium □ Low