Human activities affecting soil fertility

Ploughing and drainage

Aerates soils, increases rate of nitrogen fixation, nitrification, decomposition of DOM

Farming

Depletion of soil nutrients from:

• Soil erosion

• Biomass removal

• Inhibiting natural processes that increase nutrient levels

• Increased leaching of dissolved nutrients

Control of soil nutrient levels

Increased soil nutrient levels from:

• The addition of inorganic fertilisers or organic matter

• Supporting natural processes that increase nutrient levels e.g. N-fixation

Irrigation

Increases soil fertility where water is a limiting factor on growth by:

• Allowing plants to keep their stomata open and continue gaseous exchange when soil would otherwise be dry

• Dissolving nutrients which can be absorbed by plants in ionic form

Excessive use of heavy machinery or high livestock densities

Soil compaction → reduced aeration, waterlogging more likely

Controlling soil pH

Helps to ensure nutrients are soluble but not too easily leached