Photo AI
6.1 Explain the basic steps that a farmer should follow when selecting a pump for a specific irrigation system - NSC Agricultural Technology - Question 6 - 2017 - Paper 1
Question 6
6.1 Explain the basic steps that a farmer should follow when selecting a pump for a specific irrigation system. 6.2 Centre-pivot irrigation systems are very efficie... show full transcript
Worked Solution & Example Answer:6.1 Explain the basic steps that a farmer should follow when selecting a pump for a specific irrigation system - NSC Agricultural Technology - Question 6 - 2017 - Paper 1
Step 1
Explain the basic steps that a farmer should follow when selecting a pump for a specific irrigation system.
Answer
To select an appropriate pump for a specific irrigation system, a farmer should:
- Estimate Flow and Pressure Requirements: Determine the necessary flow rate and pressure according to the irrigation needs.
- Pump Type Selection: Decide on the best pump type, such as rotary, centrifugal, or submersible, based on the specific requirements.
- Research Pump Models: Investigate various pump models available in the market to find suitable options for the farm.
- Draft an Initial Design: Create a preliminary irrigation design that includes the estimated pressure and volume the pump will need to deliver.
- Final Assessment: Review and ensure that the chosen pump meets the cost-effectiveness criteria and is suitable for long-term use.
Step 2
Discuss the design principles that are incorporated into the sprayers of the centre-pivot system to ensure the equal distribution of water from the centre of the pivot to the outer end of the pivot.
Answer
The design principles include:
- Nozzle Size Variation: The nozzles are progressively smaller as they move outward, ensuring consistent water distribution as the distance from the centre increases.
- Pressure Regulation: Incorporating pressure regulators on down pipes helps to equalize the water pressure throughout the system.
- Wheel Mobility: Adjusting the speed of the wheels ensures that the outer circles cover greater distances without compromising water delivery.
Step 3
Explain why calibration of the water distribution system on a centre pivot is necessary. Refer to the movement of the centre pivot and the layout of the land.
Answer
Calibration is crucial to ensure that water is evenly distributed based on land layout and pivot movements. This involves:
- Movement Considerations: As the centre pivot moves, the outer wheels cover a greater area, necessitating adjustments in the water flow to compensate for variations in speed between inner and outer wheels.
- Land Topography: Calibration accounts for the gradient and layout of the land to prevent over or under irrigation.
Step 4
State TWO common soil problems when water distribution is not correctly calibrated in an irrigation system.
Answer
Common soil problems include:
- Soil Erosion: Improper calibration can lead to excess water flow, which washes away top soil.
- Salinization: Inadequate distribution may cause brackish conditions from salts accumulating in the soil.
Step 5
Name a device that can be used to determine soil water content and explain the necessity for such a device in irrigation management.
Answer
A Neutron Probe is a device used to measure soil water content. Its necessity lies in:
- Improving Plant Growth: It helps in monitoring plant estalishment and growth.
- Avoiding Over/Under Irrigation: It prevents water wastage and assures optimal irrigation.
Step 6
Explain why evapotranspiration is measured in a maize crop.
Answer
Evapotranspiration is measured to accurately schedule irrigation. The measurement helps in:
- Water Needs Assessment: It indicates how much water is lost to the atmosphere and thus informs irrigation timing.
- Weather Condition Adjustment: The measurement aids in adjusting irrigation plans according to varying weather conditions such as wind, temperature, and humidity.
Step 7
Calculate the flow rate of water in a pipe delivery system when it takes 5 minutes to fill a 15 000 litre tank. Show ALL calculations.
Answer
To calculate the flow rate:
- Flow Rate Formula: Flow rate = Volume / Time
- Values: Volume = 15,000 litres, Time = 5 minutes = 300 seconds.
- Calculation: [ Flow , Rate = \frac{15,000 , litres}{300 , seconds} = 50 , litres/second ] Therefore, the flow rate is 50 litres per second.
Step 8
Step 9
Describe the working of the water purification system in QUESTION 6.5.1.
Answer
The purification system operates as follows:
- Filtration Stages: Water passes through three different filter membranes: the first filters larger particles, while subsequent membranes capture smaller particles.
- Water Cartridge: The final cartridge further cleanses the water, ensuring safety for consumption.
Step 10
Step 11
Describe the process of breaking down household sewage in a septic tank.
Answer
The process involves:
- Bacterial Action: Sewage is broken down anaerobically by bacteria within the tank, reducing solid waste.
- Sedimentation: The solids settle at the bottom while clarified liquid exits the tank.
- Ecosystem Regulation: Minimal remaining solids are kept in the tank to promote natural breakdown processes.