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2. (a) (i) Draw a labelled diagram of the soil profile of a named soil type - Leaving Cert Agricultural Science - Question 2 - 2018
Question 2
2. (a) (i) Draw a labelled diagram of the soil profile of a named soil type. (ii) Outline the factors responsible for creating any two of the soil horizons shown... show full transcript
Worked Solution & Example Answer:2. (a) (i) Draw a labelled diagram of the soil profile of a named soil type - Leaving Cert Agricultural Science - Question 2 - 2018
Step 1
(a) (i) Draw a labelled diagram of the soil profile of a named soil type.
Answer
To draw a labelled diagram of a soil profile, I will select 'Loam' as the soil type. The diagram should depict the following horizons:
- O Horizon: Organic matter layer, rich in decomposed plants and animals.
- A Horizon: Also known as the topsoil, where most biological activity occurs, containing a mix of organic material and minerals.
- B Horizon: Subsoil layer, where minerals leach down from topsoil, often lower in organic material.
- C Horizon: Parent material, consisting of weathered rock or sediment.
Labels should clearly mark each horizon with a description, ensuring that the diagram is accurately represented.
Step 2
(a) (ii) Outline the factors responsible for creating any two of the soil horizons shown.
Answer
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O Horizon: Factors responsible for its creation include:
- Decomposition of Organic Material: As plants and animals die, their remains decompose, contributing to the organic matter in this layer.
- Biological Activity: Soil organisms, like fungi and bacteria, break down organic material, enriching the O horizon.
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A Horizon: Factors include:
- Weathering of Rocks: Physical and chemical weathering releases minerals that mix with organic matter in this horizon.
- Leaching: The process where water percolates down, washing away nutrients from the upper layers and depositing them into the A horizon.
Step 3
(b) (i) Explain the term soil texture.
Answer
Soil texture refers to the relative proportions of different particle sizes in a soil sample, specifically sand, silt, and clay. This property influences various soil characteristics, including drainage, fertility, and the soil's ability to hold nutrients. A loamy texture, which is a balance of sand, silt, and clay, is often considered ideal for agricultural use due to its favorable water retention and aeration properties.
Step 4
(b) (ii) Name any two soil texture types and compare them under the following headings: 1. Fertility 2. Temperature 3. Drainage 4. Ease of tilling.
Answer
- Clay vs. Sandy Soil:
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Fertility:
- Clay: High fertility due to its ability to hold nutrients.
- Sandy: Low fertility as it drains nutrients quickly.
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Temperature:
- Clay: Slower to warm up in spring due to its density.
- Sandy: Warmer faster than clay, making it suitable for early planting.
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Drainage:
- Clay: Poor drainage, leading to waterlogging.
- Sandy: Excellent drainage, preventing water retention.
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Ease of Tilling:
- Clay: Difficult to till when wet, can form hard clumps.
- Sandy: Easy to till owing to loose texture.
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Step 5
(c) Describe an experiment to show the activity of earthworms in the soil.
Answer
To demonstrate the activity of earthworms, the following experiment can be conducted:
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Materials Needed: Earthworms, various soil types (sand, clay, chalk), container, and organic matter (like leaves or vegetable scraps).
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Experimental Setup: Layer the different soil types in a container, placing earthworms on top of the layers. Add organic matter on top of the worms and cover the container lightly to control moisture.
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Observation Period: Leave the setup in a controlled environment for a week.
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Data Collection: Check daily for signs of earthworm activity such as burrowing paths, the quality of soil, and possible changes in texture or structure.
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Analysis: After a week, investigate how much organic matter was processed by the earthworms and document changes in soil aeration and structure, concluding how earthworms improve soil health.