Lesson Notes By Weeks and Term v4 - SHS 1

Lesson Video

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Performance objectives

• Explain climate variability and its importance in agriculture.
• Discuss how drought and pestilence affect crop yields in Ghana.
• Analyze the link between climate variability and farm productivity.
• Suggest strategies to manage the impacts of climate variability.

Lesson summary

Welcome, students. Today, we are discussing a very important topic that affects every single one of us, from the food we eat to the money our families make. Have you noticed that sometimes the rains start very late? Or that the harmattan seems drier and longer some years? These changes are part of what we call Climate Variability. In this lesson, we will explore how these variations in our climate are creating serious problems for our farmers, specifically by causing more droughts, more pest and disease outbreaks (pestilence), and ultimately, causing them to harvest less food (decreasing crop yields).

Lesson notes

This lesson focuses on a cause-and-effect chain. Climate Variability is the *cause*, and it leads to three major *effects* in agriculture that we will discuss: Drought, Pestilence, and Decreasing Yields. A. What is Climate Variability? Definition: Climate Variability refers to the year-to-year variations and fluctuations in climate patterns (like temperature, rainfall, wind) around a long-term average. It is different from *climate change*, which is a long-term shift in these averages over decades. Simple Analogy: Think of your school grades. Your *average* grade in Agricultural Science might be 75% (this is like the 'climate'). In one term, you might get 80%, and in another, you get 70%. This fluctuation around your average is *variability*. Climate change would be if your average slowly shifted from 75% to 65% over many years. In the Ghanaian Context: Rainfall: The rainy season is expected to start in March/April in the south, but some years it starts in May (variability). Or, there might be a long, unexpected dry spell in the middle of the rainy season. Temperature: Some years, the harmattan season is extremely cold and dry, while in other years it is milder. B. The Triple Threat to Ghanaian Agriculture

Climate variability creates a chain reaction of problems for our farmers. Increasing Drought Definition: A drought is a prolonged period with an abnormal shortage of rainfall, resulting in a water scarcity that damages crops and affects the environment. The Link to Climate Variability: Late Onset of Rains: When the rainy season starts weeks or even a month late, farmers who have already planted their seeds face a problem. The seeds may fail to germinate or the young seedlings will wither and die. This is a form of drought. Poor Rainfall Distribution: Climate variability can mean that even if the total amount of rain for the year is normal, it might not fall when it's needed. For example, we might have very heavy downpours for two weeks, causing floods, followed by a month with no rain at all during the critical flowering stage of a crop like maize. This dry spell is a drought that can ruin the harvest. Ghanaian Example: A maize farmer in the Northern Region depends on a single rainy season (from May to October). If the rains in June and July are poor (variability), the maize plants will be stunted and may not produce cobs. This is a direct experience of drought leading to crop failure. Increasing Pestilence Definition: Pestilence refers to a widespread and destructive outbreak of pests (like insects) or diseases that attack crops. The Link to Climate Variability: Temperature Effects: Warmer temperatures, a feature of climate variability, can speed up the life cycle of many insects. This means they can reproduce faster and produce more generations in a single growing season, leading to a population explosion. Plant Stress: Drought-stressed plants are like humans with a weak immune system. They are much more vulnerable to attacks from pests and diseases. Their natural defence mechanisms are weakened, making them an easy target. Pest Migration: Changes in wind patterns and temperature can allow pests to move into new areas where they were not previously a problem. Ghanaian Example: The Fall Armyworm is a perfect example. This devastating pest thrives in warmer, drier conditions. The erratic rainfall patterns associated with climate variability create the perfect environment for the Fall Armyworm to multiply rapidly and destroy vast fields of maize, a staple food in Ghana. Decreasing Crop Yields Definition: Crop Yield is the measure of the amount of a crop harvested per unit area of land (e.g., kilograms per hectare or bags per acre). Decreasing yield means farmers are getting less harvest from the same piece of land. The Link to Drought and Pestilence: This is the final, devastating outcome. How Drought Reduces Yield: Poor Germination: Seeds don't sprout, reducing plant population. Stunted Growth: Lack of water means plants cannot absorb nutrients properly, so they remain small. Failed Pollination: For crops like maize, severe drought during the tasseling and silking stage means no kernels will form on the cob, resulting in zero yield. Smaller Grains/Tubers: For crops like rice or yam, water shortage leads to smaller grains or tubers, reducing the total weight of the harvest. How Pestilence Reduces Yield: Reduced Photosynthesis: Pests like caterpillars eat leaves, which are the plant's "food factory." With fewer leaves, the plant cannot produce enough energy to grow or form fruits. Direct Damage: Pests like fruit borers directly damage the part of the crop we harvest (e.g., cocoa pods, tomatoes, garden eggs), making them unsellable and inedible. Disease Damage: Fungal or viral diseases can cause wilting, rot, or spots on leaves and fruits, leading to total crop loss.

Summary of the Connection:

`Climate Variability` (e.g., late rains, high temperatures) → `Leads to Drought & Favourable Pest Conditions` → `Drought stresses plants & Pests multiply` → `Stressed plants are attacked by more pests (Pestilence)` → `Both drought and pestilence damage the crop` → `Result: Decreasing Crop Yields`

Evaluation guide

• Discuss increasing drought, pestilence and decreasing crop yields.
• Enquiry -Based Learning: Learners in small mixed groups surf the internet and read about
• the topic before the lesson.
• Talk for Learning: Various groups discuss information generated from reading assignment s