Lesson Notes By Weeks and Term v4 - SHS 1
PRINCIPLES OF NATURAL RESOURCE CONSERVATION IN AGRICULTURE
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PRINCIPLES OF NATURAL RESOURCE CONSERVATION IN AGRICULTURE
Download the Lessonotes Mobile Ghana app for faster lesson access on Android and iPhone.
Subject: Agriculture
Class: SHS 1
Term: 2nd Term
Week: 13
Grade code: 1.3.2.LI.3
Strand code: 3
Sub-strand code: 2
Content standard code: 1.3.2.CS.2
Indicator code: 1.3.2.LI.3
Theme: FOOD PRODUCTION AND NATURAL RESOURCE CONSERVATION
Subtheme: PRINCIPLES OF NATURAL RESOURCE CONSERVATION IN AGRICULTURE
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Soil is the foundation of almost all life on land and the most critical natural resource for agriculture in Ghana. From the yams in the Brong Ahafo Region to the cocoa in the Ashanti Region and the vegetables we grow in our backyards, everything depends on healthy soil. To conserve this precious resource, we must first understand what it is made of. Thinking of soil as just "dirt" is a mistake; it is a complex, living system. This lesson will break down soil into its fundamental components, helping us understand how to manage it for sustainable food production.
This section breaks down the core content of the lesson. The teacher will use a combination of lecture, discussion, and demonstration. What is Soil? Soil is the upper layer of the earth's crust, which is formed by the weathering of rocks and the decomposition of organic materials over a long period. It is a dynamic natural body capable of supporting plant life. The Five Components of Soil A typical, healthy loam soil suitable for agriculture has five main components, which can be grouped by their relative proportions.
Ideal Soil Composition (by volume): Mineral Matter: 45% Organic Matter: 5% Soil Water: 25% Soil Air: 25% Living Organisms: (Part of organic matter and pore spaces)
![A simple pie chart showing these percentages would be drawn on the board or displayed here.]
**1. Mineral Matter (45%) ** This is the non-living, inorganic part of the soil. It forms the "skeleton" or framework of the soil. Origin: It comes from the gradual breakdown of parent rocks through a process called weathering. This can be physical (wind, rain, temperature changes) or chemical (reactions with water and air). Composition: Mineral matter consists of particles of different sizes: Sand: Largest particles (0.05mm - 2.0mm). Feels gritty. Allows water and air to pass through easily (high permeability), but does not hold water well. Sandy soils are common in Ghana's coastal areas. Silt: Medium-sized particles (0.002mm - 0.05mm). Feels smooth or floury when dry, and silky when wet. Holds water better than sand. Clay: Smallest particles (< 0.002mm). Feels sticky when wet and hard when dry. Clay particles can hold a lot of water and nutrients but may have poor drainage and aeration. Many soils in the forest zones of Ghana are rich in clay. Importance: Provides anchorage and support for plant roots. Supplies essential mineral nutrients for plants (e.g., potassium, phosphorus, calcium) as the particles slowly weather. The combination of sand, silt, and clay determines the soil's texture, which affects how it is farmed. Organic Matter (5%) This is the living and dead plant and animal material in the soil. Origin: It comes from decayed plant roots, leaves, dead animals, and microorganisms. Fully decomposed, stable organic matter is called humus. Characteristics: Humus is dark-coloured, spongy, and gives fertile topsoil its rich, dark look. Importance: Nutrient Supply: It is a major source of plant nutrients, especially nitrogen. As it decomposes, it releases nutrients in a form plants can use. Water Retention: Humus acts like a sponge, holding large amounts of water and making it available to plants, which is crucial during the short dry spells in our rainy season. Soil Structure: It helps bind mineral particles together to form stable clumps called aggregates. This improves soil aeration and drainage. Food for Organisms: It provides food and energy for beneficial soil microorganisms. Soil Water (25%) This is the water held within the spaces (pores) between soil particles. Origin: Rain, irrigation. Function: It is not pure water but a soil solution because it contains dissolved mineral nutrients. Importance: Nutrient Transport: Plants absorb dissolved nutrients through their roots from this soil solution. Photosynthesis: It is an essential raw material for photosynthesis. Temperature Regulation: It helps regulate soil temperature, protecting roots from extreme heat. Turgidity: It keeps plant cells firm and prevents wilting. Soil Air (25%) This is the air that fills the pore spaces in the soil not occupied by water. Composition: Similar to the air we breathe but usually with more carbon dioxide and less oxygen. Importance: Root Respiration: Plant roots need oxygen to respire and generate energy for nutrient and water uptake. This is why waterlogged soils (where water pushes out all the air) can "drown" most crops like maize and cassava. Organism Respiration: Soil organisms (like earthworms and bacteria) need oxygen to survive and carry out their functions, such as decomposing organic matter. Living Organisms These are all the plants and animals living in the soil. They are a vital, active part of the soil. Examples: Macro-organisms: Earthworms, termites, millipedes, insects, plant roots. Micro-organisms: Bacteria, fungi, algae, protozoa. Importance: Decomposition: Micro-organisms are the primary decomposers, breaking down complex organic matter into simple nutrients for plants. Soil Structure: Earthworms burrow through the soil, creating channels that improve aeration and water infiltration. Their castings also help build good soil structure. Nutrient Cycling: Certain bacteria (like *Rhizobium* in the root nodules of cowpea) can "fix" nitrogen from the air into a form plants can use.