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i) Explain how an iron pan is formed in a soil - Leaving Cert Agricultural Science - Question a - 2017
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i) Explain how an iron pan is formed in a soil. ii) What are the effects of an iron pan in a soil? iii) Name the soil group in which an iron pan is most likely to ... show full transcript
Worked Solution & Example Answer:i) Explain how an iron pan is formed in a soil - Leaving Cert Agricultural Science - Question a - 2017
Step 1
Explain how an iron pan is formed in a soil.
Answer
An iron pan forms in soil typically due to conditions of high rainfall, high altitude, low temperatures, or low evaporation rates leading to low pH levels (acidic conditions). In such environments, iron leaches down from the A horizon (top layer of soil) and accumulates in the B horizon (subsoil) where it becomes solidified, resulting in the formation of a hard, impermeable layer known as an iron pan.
Step 2
What are the effects of an iron pan in a soil?
Answer
The presence of an iron pan in the soil has several detrimental effects. Firstly, it can lead to waterlogging due to poor drainage, limiting root growth. Secondly, it reduces aeration, which negatively impacts microbial activity and organic matter decomposition. This results in decreased plant growth and can restrict the type of vegetation that can thrive in such conditions.
Step 3
Step 4
How can an iron pan in a soil be removed?
Answer
An effective method to remove an iron pan from soil involves deep ploughing or the use of a subsoiler. This technique breaks up the compacted layer, allowing for improved drainage and root penetration, ultimately restoring the soil's fertility and structure.
Step 5
Describe the method of taking soil samples for testing.
Answer
To take soil samples, first divide the area into regions approximately 2-4 hectares in size. Using a W-shaped pattern, collect soil samples at intervals of at least 10 cm deep. Ensure that samples are taken away from gateways, ditches, and other non-representative areas. Mix the samples thoroughly and label them according to the sampled area for accurate analysis.
Step 6
Describe a method to measure the pH of a soil sample.
Answer
To measure the pH of a soil sample, add a specific amount of distilled water to a beaker containing the soil. Stir the mixture well, then filter or allow it to settle. Use a pH meter or pH indicator to measure the pH level accurately. Alternatively, a universal pH indicator can be used to compare the color change against a pH chart.