Lesson Notes By Weeks and Term v4 - SHS 3

Lesson Video

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Performance objectives

• Describe different types of irrigation systems.
• Explain the importance of irrigation for productivity.
• Demonstrate using basic irrigation machinery.
• Analyze the effectiveness of different irrigation methods.

Lesson summary

This lesson focuses on simple irrigation systems, which are a crucial form of agricultural machinery and technology. In Ghana, our agriculture is heavily dependent on rainfall, which can be unreliable due to climate change, leading to unpredictable seasons and long dry spells like the harmattan. For high-value crops like mangoes, oranges, cocoa, and oil palm, a consistent water supply is essential for survival, growth, and fruiting. By understanding and adapting simple irrigation systems, farmers can overcome the challenges of erratic rainfall, increase their yields, produce crops all year round, and improve their livelihoods.

Lesson notes

A. What is Irrigation?

Irrigation is the artificial application of water to land or soil to assist in the growing of crops. Its primary purpose is to supplement natural rainfall, especially during dry seasons or in areas with low rainfall, ensuring that crops receive the water they need for optimal growth and yield.

For plantation and fruit trees, which are long-term investments, irrigation is critical because: They have a long establishment period where young plants are vulnerable to drought. Water is essential during flowering and fruit development to prevent flower drop and ensure large, juicy fruits. Consistent water supply can lead to off-season production, fetching higher prices in the market. B. Types of Simple Irrigation Systems

These are systems that are relatively low-cost, easy to operate, and maintain, making them suitable for small to medium-scale farmers in Ghana. Surface Irrigation (Furrow and Basin Method) Principle: Water is applied directly to the soil surface and flows over the land by gravity. Furrow Irrigation: Small channels (furrows) are dug between rows of trees, and water is directed down these furrows. The water seeps sideways and downwards to the tree roots. Basin Irrigation: A small bund or ridge is created around the base of each tree, or a group of trees, to form a small basin. The basin is then filled with water, which slowly infiltrates the soil. Adaptation in Ghana: Commonly used for citrus (orange, lime) and mango orchards where trees are planted in regular rows. It is favoured where water is abundant (near a river or dam) and electricity for pumping is not reliable. Advantages: Very low initial cost; no complex machinery required. Low energy requirement as it relies on gravity. Disadvantages: High water loss due to evaporation and deep percolation. Can be inefficient, with uneven water distribution. Requires the land to be relatively level. Can increase soil erosion if not managed properly. Sprinkler Irrigation Principle: Water is pumped through a network of pipes and sprayed into the air through rotating sprinkler heads, falling on the crops like natural rainfall. Adaptation in Ghana: Often used in commercial nurseries for raising seedlings of plantation crops like cocoa, oil palm, and cashew. It is also used in established citrus and mango farms, especially in the transitional and coastal savanna zones. Advantages: Covers a large area uniformly. Suitable for most soil types. Can be used on unleveled land. Disadvantages: High water loss through evaporation, especially on hot, windy days. Can promote the spread of fungal diseases as it wets the leaves. Higher initial cost and energy (pumping) requirement compared to surface irrigation. Drip (or Trickle) Irrigation Principle: This is a highly efficient system where water is delivered slowly and directly to the root zone of each plant through a network of plastic pipes and small outlets called emitters or drippers. Adaptation in Ghana: This is becoming the most preferred system for commercial fruit tree farming, especially for mangoes in the Northern and Bono regions, and for vegetables. It is ideal for arid and semi-arid areas where water is scarce. Advantages: Highest water efficiency (up to 95%); minimal loss to evaporation. Reduces weed growth as only the area around the plant is watered. Fertilizers can be applied directly with the water (fertigation), saving labour and nutrients. Reduces the risk of leaf diseases. Disadvantages: High initial installation cost. Emitters can get clogged by sand or salt particles, requiring good water filtration and regular maintenance. Requires a reliable, clean water source. Manual/Bucket Irrigation Principle: The most basic method, involving fetching water with buckets or watering cans and applying it directly to the base of each plant. Adaptation in Ghana: Very common for backyard gardens and for nursing seedlings of cocoa, oil palm, and fruit trees on a small scale. It is the primary method for very smallholder farmers without capital. Advantages: Extremely low cost. Simple and requires no technical skill. Disadvantages: Very labour-intensive and time-consuming. Impractical for farms larger than a small plot. C. Extent of Adaptation of Irrigation in Ghana

Evaluation guide

• Describe the extent of adaptation to simple irrigation systems for the cultivation of
• selected plantation and fruit trees .
• Project -Based Learning: Practice irrigation on selected plantation s and fruit trees based on the
• conceptual