Lesson Notes By Weeks and Term v4 - SHS 1
AGRICULTURAL MACHINERIES
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AGRICULTURAL MACHINERIES
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Subject: Agricultural Science
Class: SHS 1
Term: 2nd Term
Week: 12
Grade code: 2.1.3.LI.2
Strand code: 1
Sub-strand code: 3
Content standard code: 2.1.3.CS.2
Indicator code: 2.1.3.LI.2
Theme: NEW DAWN AGRICULTURE
Subtheme: AGRICULTURAL MACHINERIES
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This lesson introduces students to the world of agricultural machinery, a critical component of modern farming. For centuries, Ghanaian farmers have relied on simple tools like the hoe and cutlass. While effective for small-scale farming, these tools involve immense physical labour (drudgery) and limit the size of farms. Agricultural mechanization—the use of machines in farming—is the key to increasing food production, ensuring food security for our nation, and making agriculture a more attractive and profitable business.
This section covers the core content for the lesson. It is designed to be taught directly to the students. A. What is Agricultural Mechanization? Definition: Agricultural mechanization is the process of using machinery to replace human and animal power in agricultural operations. It ranges from simple hand-operated tools (like a hand-cranked maize sheller) to complex, engine-powered machines (like a tractor or combine harvester). Key Terms: Tractor: The primary power source on a mechanized farm. It pulls, pushes, or powers other machines (implements). Think of it as the "engine" of the farm. Implement: A machine or tool that is attached to and powered by a tractor to perform a specific task (e.g., a plough, a harrow). B. Classification of Farm Machinery by Function
We can classify farm machinery based on the job it performs in the crop production cycle. Tillage Machinery (Land Preparation) Tillage is the process of preparing the soil for planting. It is divided into two main stages: primary and secondary tillage. Primary Tillage Machinery: These are used for the first, deep, and rough cultivation of the land. Their main job is to break open hard, compacted, or new soil. Example 1: Mouldboard Plough Function: It cuts, lifts, turns, and pulverizes the soil. It is very effective at burying weeds and crop residues, which helps improve soil fertility as they decompose. Principle of Operation: It has a curved part called a mouldboard and a sharp cutting edge called a ploughshare. As the tractor pulls it, the ploughshare cuts into the soil, and the mouldboard lifts and completely flips the slice of soil (called a furrow slice). Best for: Loamy soils, areas with heavy weed cover. Example 2: Disc Plough Function: Similar to the mouldboard plough, it breaks hard ground. However, it uses a set of large, rotating, concave steel discs. Principle of Operation: The discs are set at an angle. As the tractor pulls the plough, the sharp edges of the discs cut into the soil, and their rotation breaks and lifts the soil. Best for: Hard, dry, sticky, or stony soils where a mouldboard plough might get damaged or stuck. Common in the Savannah regions of Ghana. Secondary Tillage Machinery: These are used after primary tillage to create a finer, smoother, and more level seedbed. They break up the large soil clods left by the ploughs. Example 1: Harrows (e.g., Disc Harrow, Spike Tooth Harrow) Function: To break soil clods into smaller pieces (pulverization), level the field, and remove shallow-rooted weeds. Principle of Operation: A Disc Harrow uses smaller discs than a disc plough to chop up the soil. A Spike Tooth Harrow is like a giant rake with metal spikes that are dragged through the soil to break up clods and level the surface. Analogy: If primary tillage is like using a pickaxe to break up hard ground, secondary tillage is like using a rake to make the surface smooth and ready for planting. Planting Machinery These machines are designed to place seeds or seedlings into the soil with precision. Example 1: Planter (e.g., Maize Planter) Function: To sow large seeds like maize, beans, and groundnuts in rows at a specific depth and spacing. Principle of Operation: It has a container (hopper) for the seeds, a mechanism (metering device) to pick up single seeds at regular intervals, a furrow opener to create a small trench, a tube to drop the seed, and a press wheel to cover the seed with soil and firm it. Advantage: Ensures uniform germination and makes subsequent operations like weeding and harvesting easier. Example 2: Seed Drill Function: To sow small-grained seeds like rice and wheat in continuous rows. Principle of Operation: Similar to a planter but drops a continuous stream of seeds instead of single seeds. Crop Maintenance Machinery These are used after planting to care for the growing crop. Example: Sprayer (e.g., Boom Sprayer) Function: To apply liquids like herbicides (to kill weeds), pesticides (to kill pests), or foliar fertilizers. Principle of Operation: A large tank holds the chemical mixture. A pump powered by the tractor forces the liquid through hoses to a long arm (the boom), which has many nozzles that spray a fine mist over the crop. For smaller farms, a Knapsack Sprayer is used. Harvesting Machinery These machines are used to gather mature crops from the field. Example: Combine Harvester Function: A complex machine that performs multiple harvesting operations at once: reaping (cutting the crop), threshing (separating the grain from the stalk), and winnowing/cleaning (removing chaff and dirt). Principle of Operation: The front part (header) cuts the crop (e.g., rice, maize). The crop is then fed into a rotating drum that threshes it. The heavy grains fall through sieves while powerful fans blow away the lighter chaff and straw. The clean grain is collected in a large tank on the machine. Best for: Large commercial farms for grains like rice, maize, and soybeans. It dramatically reduces labour costs and post-harvest losses. Post-Harvest Machinery These are used to process crops after they have been harvested. Example: Maize Sheller Function: To remove maize grains from the cob quickly. Principle of Operation: The cobs are fed into the machine, where a rotating, studded cylinder rubs against them, detaching the kernels which then fall through a screen. This is much faster than shelling by hand.
Guided Practice (With Solutions)
Instructions: As a class, let's work through these scenarios.