Study the picture of a centre-pivot irrigation system below and answer the questions that follow - NSC Agricultural Technology - Question 6 - 2024 - Paper 1

Farmers can utilize the following devices for effective control of the irrigation system:

1. Cell Phone: Enables remote monitoring and control of the system, allowing farmers to make adjustments from anywhere.
2. Tablet: Offers an interface for monitoring irrigation schedules and system performance manually.

When selecting fertilizers for a centre-pivot irrigation system, farmers should consider:

1. Fertiliser with a High Nutrient Content: Opt for a fertiliser that provides adequate nutrients to the crops without requiring excessive application.
2. Avoidance of Large Particles: Choose fertilisers with smaller particle sizes to prevent clogging the irrigation system, ensuring an even distribution of nutrients.

A farmer might prefer pump A over pump B when:

• Electrical Independence: Pump A does not require electrical power, making it suitable for areas without grid access.
• Mobility: If pump A can be easily moved to various locations, it enhances flexibility in irrigation practices.

When selecting a new pump for irrigation, the following factors should be taken into account:

1. Pressure Requirements: Determine the required pressure for effective irrigation.
2. Capacity of the Pump: Ensure the pump's capacity matches the irrigation needs and water supply volume.
3. Durability: Choose a pump built to withstand the operational conditions and last through multiple seasons.

PVC pipes offer several advantages over steel pipes, including:

1. Rust Resistance: PVC does not rust, leading to a longer lifespan in wet conditions.
2. Lightweight: Easier to handle and install due to their reduced weight.
3. Flexibility: PVC pipes provide more flexibility during installation, reducing the risk of breaks.

To calculate the time required to empty the water source, we will use the formula:

$ext{Time} = \frac{\text{Volume of water}}{\text{Flow rate}}$

Substituting the given values:

• Volume of water = 72,000 litres
• Flow rate = 120 litres/min

Thus, the calculation is:

$ext{Time} = \frac{72,000}{120} = 600 \text{ minutes}$

Therefore, it will take 600 minutes to empty the water source.

Two effective drainage systems for managing excess water around dairy farm buildings are:

1. Channel Drain: A trench-like structure designed to direct surface water away.
2. Drainage Ditch: A wider channel that allows for greater areas of water to be managed.

To purify brackish water, the following methods can be employed:

1. Distillation: Involves boiling water and condensing the vapor to remove salts and impurities.
2. Reverse Osmosis: Utilizes a semipermeable membrane to separate contaminants and salts from water.

The distribution field connected to a septic tank consists of:

• Narrow Trench: A trench filled with gravel or stone that helps disperse effluent from the septic tank.
• Perforated Pipes: Installed within the trench, these pipes disperse the treated wastewater evenly throughout the surrounding soil.
• Proper Sizing: The distribution field must be designed to handle the volume of wastewater efficiently to avoid saturation and ensure proper absorption.

Building a distribution field too close to drinking water installations can pose significant risks, including:

1. Contamination Risks: Septic tanks can leach harmful pathogens and chemicals that may travel to drinking water sources, compromising their safety.
2. Regulatory Compliance: Regulations often dictate a minimum distance to ensure well water remains uncontaminated.

VRT can be applied in precision farming in the following instances:

1. Precision Planting: Adjusting plant density based on soil variability and crop requirements.
2. Application of Fertilizers/Lime: Tailoring the amount of fertilizer or lime according to site-specific nutrient needs.