Lesson Notes By Weeks and Term v5 - Grade 11

Lesson Video

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Performance objectives

• Explain effective water management and irrigation techniques.
• Describe nutrient management strategies like fertilization.
• Identify common pests and integrated management strategies.
• Develop a basic crop production schedule.
• Calculate basic fertilizer application rates.

Lesson summary

Crop production is the backbone of South African agriculture and contributes significantly to our food security, economy, and job creation. Understanding best practices and efficient scheduling is crucial for maximizing yields, minimizing losses, and ensuring sustainable farming. In Week 1, we laid the groundwork by exploring the general principles of crop production. This week, we delve deeper into critical production practices focusing on water management, nutrient management, and pest and disease control and their impact on effective crop scheduling.

Lesson notes

2.1 Water Management (Irrigation) South Africa is a water-scarce country. Efficient irrigation is paramount. We need to understand different irrigation methods and how they work: Surface Irrigation: Description:* Water is applied over the soil surface. Types include flood irrigation, furrow irrigation, and border strip irrigation.

Pros:* Relatively low initial cost, simple to operate.

Cons: Low water use efficiency (high water loss through evaporation and runoff), uneven water distribution, can lead to soil erosion and waterlogging.

Specific issue in SA: Not suitable for all terrains and soil types, particularly problematic on steep slopes in KwaZulu-Natal.

Example:* Flood irrigation is often used for rice paddies but is generally unsustainable for most other crops in SA due to water scarcity. Furrow irrigation can be used for maize, but requires careful land preparation to ensure uniform slope.

Sprinkler Irrigation: Description:* Water is sprayed into the air and falls on the plants like rain. Types include overhead sprinklers, center pivot irrigation, and traveling guns.

Pros:* More uniform water distribution than surface irrigation, adaptable to various terrains, can be used for frost protection.

Cons: Higher initial cost, susceptible to wind drift and evaporation losses, can promote foliar diseases.

Specific issue in SA: High energy costs associated with pumping water, especially problematic during Eskom load shedding.

Example:* Centre pivot irrigation is common on large-scale maize and wheat farms in the Free State and North West provinces.

Drip Irrigation (Micro-Irrigation): Description:* Water is applied slowly and directly to the root zone through emitters.

Pros:* Highest water use efficiency, minimizes water loss, reduces weed growth, allows for fertigation (application of fertilizers through the irrigation system).

Cons: Highest initial cost, emitters can get clogged, requires careful system maintenance.

Specific issue in SA: Vulnerable to damage from rodents and UV degradation, requires specialized filtration to prevent clogging due to poor water quality in some areas.

Example:* Drip irrigation is widely used in vineyards in the Western Cape and for vegetable production in various regions.

Subsurface Drip Irrigation (SDI): Description:* Drip irrigation lines are buried beneath the soil surface.

Pros:* Even higher water use efficiency than drip irrigation, minimizes surface evaporation, reduces weed growth, less susceptible to damage.

Cons: Highest initial cost, more difficult to maintain, potential for root intrusion into emitters.

Specific issue in SA: High level of technical expertise required for installation and maintenance, not readily accessible for small-scale farmers.

Example:* SDI is utilized on large-scale sugarcane farms in KwaZulu-Natal. Considerations for choosing an irrigation method: Crop type, soil type, water availability, topography, budget, and energy costs. For example, sandy soils require more frequent irrigation than clay soils due to their lower water-holding capacity. 2.2 Nutrient Management (Fertilization and Organic Amendments) Plants need essential nutrients for growth. Soil testing is critical to determine nutrient deficiencies.

Macronutrients: Nitrogen (N), Phosphorus (P), Potassium (K). These are needed in larger quantities.

Micronutrients: Iron (Fe), Manganese (Mn), Zinc (Zn), Copper (Cu), Boron (B), Molybdenum (Mo). These are needed in smaller quantities.

Fertilizers: Description:* Inorganic or synthetic compounds that provide specific nutrients.

Types:* Nitrogenous fertilizers (e.g., urea, ammonium nitrate), phosphatic fertilizers (e.g., superphosphate), potassic fertilizers (e.g., potassium chloride), compound fertilizers (NPK).

Application Methods: Broadcasting (spreading evenly over the soil surface), band application (placing fertilizer in bands near the seed row), side-dressing (applying fertilizer along the plant rows), foliar application (spraying fertilizer directly onto the leaves).

Example in SA: Applying 2:3:2 (22) + Zn to maize at planting.

Calculating Fertilizer Rates:* This is CRUCIA

L. Step 1: Determine the nutrient requirement of the crop. This information can be found in crop guides or by consulting with agricultural advisors.

Step 2: Analyze the soil test results. This will tell you how much of each nutrient is already present in the soil.

Step 3: Calculate the difference between the nutrient requirement and the soil nutrient level. This will tell you how much of each nutrient needs to be added as fertilizer.

Step 4: Choose a fertilizer that contains the nutrients you need.

Step 5: Calculate the amount of fertilizer to apply based on the fertilizer's nutrient content.

Example:* If maize requires 120 kg N/ha and the soil test shows 30 kg N/ha, then you need to apply 90 kg N/ha. If you are using urea (46% N), then you need to apply 90 kg N / 0.46 = 195.65 kg urea/ha.