How human activities affect soil fertility

Question 1

How can ploughing and drainage affect soils?

Answer 1

• makes soils more aerobic

- increases rates of nitrogen fixation, nitrification, and the decomposition of dead organic matter

Question 2

How do human activities affect soil nutrient levels?

Answer 2

• farmers add inorganic fertilisers and organic matter
• farmers can also deplete soil nutrient levels due to soil erosion, biomass removal or by increased leaching of dissolved nutrients

Question 3

How does irrigation affect soils?

Answer 3

• increases fertility where water is a limiting factor on growth
• allows plants to keep their stomata open
• allows plants to continue gaseous exchange when soil would otherwise be dry
• water dissolves nutrients which can be absorbed by plants in ionic form

Question 4

What effect does soil compaction have?

Answer 4

• caused by excessive use of heavy machinery or high livestock densities
• this reduces aeration
• makes waterlogging more likely, especially when the soil is wet

Question 5

Why do farmers need to control the pH of soils?

Answer 5

• helps to ensure nutrients are soluble but not too easily leached