Lesson Notes By Weeks and Term v5 - Grade 10

Lesson Video

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Performance objectives

• Define different types of tillage like primary, secondary, and no-till.
• Describe the purpose of preparing soil for planting.
• Compare the advantages and disadvantages of different tillage systems.
• Identify factors that influence a farmer's choice of tillage method.

Lesson summary

Soil preparation and cultivation are fundamental agricultural practices that directly impact crop yield, soil health, and overall farm profitability. In South Africa, effective soil preparation is crucial due to diverse soil types, varying rainfall patterns, and the need for sustainable agricultural practices that can address food security and climate change challenges. From small-scale subsistence farming to large commercial operations, understanding these practices is essential for successful agricultural production. Poor soil preparation can lead to reduced yields, increased erosion, higher input costs (e.g., fertilisers), and ultimately, unsustainable farming.

Lesson notes

2. 1. Purpose of Soil Preparation and Cultivation The primary objectives of soil preparation and cultivation are to: Create a suitable seedbed: This involves creating a fine, firm seedbed that allows for good seed-to-soil contact, facilitating germination and seedling establishment.

Improve soil structure: Tillage can break up compacted soil, improving aeration, drainage, and root penetration.

Control weeds: Cultivation can uproot or bury weeds, reducing competition with crops for water, nutrients, and sunlight. Incorporate organic matter and fertilizers: Soil preparation allows for the incorporation of manure, compost, and other organic matter, as well as the application of fertilizers.

Manage crop residue: Tillage can incorporate crop residue into the soil, improving soil organic matter and nutrient cycling, or remove it to prevent disease and pest problems.

Control soil pests and diseases: In some cases, tillage can help to control soil-borne pests and diseases. 2.

2. Types of Tillage Systems Conventional Tillage: This involves intensive soil manipulation using implements like ploughs, discs, and harrows. It typically involves primary tillage (e.g., ploughing) followed by secondary tillage (e.g., harrowing).

Primary Tillage:* The initial breaking up of the soil to loosen it and bury crop residue.

Examples include: Ploughing:* Using a mouldboard plough to invert the soil, burying residue and weeds. Suitable for heavy clay soils.

Chisel Ploughing:* Using a chisel plough to loosen the soil without inverting it, leaving more residue on the surface. Suitable for lighter soils and erosion-prone areas.

Secondary Tillage:* Subsequent operations to refine the seedbed and prepare it for planting.

Examples include: Harrowing:* Using a disc harrow or spring-tooth harrow to break up clods, level the soil, and incorporate herbicides.

Rolling:* Using a roller to compact the soil, creating a firm seedbed.

Example: A maize farmer in the Free State, with heavy clay soil, might choose conventional tillage. They would first use a mouldboard plough to invert the soil and bury the previous season's maize stover. Then, they would use a disc harrow to break up the clods and create a fine seedbed for planting maize.

Advantages: Good weed control, rapid seedbed preparation, effective incorporation of fertilizers and organic matter.

Disadvantages: High energy consumption, increased soil erosion, loss of soil organic matter, damage to soil structure.

Reduced Tillage: This involves minimizing soil disturbance by reducing the number of tillage operations and/or the intensity of tillage.

Minimum Tillage:* Reducing tillage to the minimum necessary for seed germination and crop establishment.

Ridge Tillage:* Planting crops on ridges, with tillage only occurring on the ridges.

Strip Tillage:* Tilling only a narrow strip of soil where the seeds will be planted, leaving the rest of the soil undisturbed.

Example: A soybean farmer in KwaZulu-Natal, aiming to conserve soil moisture and reduce erosion, might choose reduced tillage. They could use a chisel plough to loosen the soil without inverting it, leaving crop residue on the surface. Then, they could use a no-till planter to plant soybeans directly into the residue.

Advantages: Reduced soil erosion, improved water infiltration, increased soil organic matter, lower energy consumption.

Disadvantages: Potential for increased weed pressure, slower seedbed preparation, requires specialized equipment.

Conservation Tillage: This is a system that aims to conserve soil, water, and energy by minimizing soil disturbance and maximizing crop residue cover. No-till farming is a key component of conservation tillage.

No-Till Farming:* Planting crops directly into undisturbed soil, with no tillage operations. Relies on herbicides for weed control and specialized planters.

Example: A sunflower farmer in the Western Cape, practicing conservation agriculture, might choose no-till farming. They would plant sunflowers directly into the previous crop residue (e.g., wheat stubble) using a no-till planter. They would rely on herbicides to control weeds.

Advantages: Significant reduction in soil erosion, improved water infiltration, increased soil organic matter, reduced energy consumption, improved soil biodiversity.

Disadvantages: Requires specialized equipment and management skills, reliance on herbicides for weed control, potential for increased pest and disease problems, slower soil warming in spring. 2.

3. Factors Affecting Tillage Choices Several factors influence the choice of tillage system, including: Soil Type: Clay soils require more intensive tillage than sandy soils.

Climate: Rainfall patterns influence the need for soil conservation measures.

Crop Type: Some crops are more sensitive to soil compaction than others.

Weed Pressure: High weed pressure may require more intensive tillage for weed control.