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Increased soil acidity

Impact

Soil acidity is a naturally occurring phenomenon that can be escalated by human activity.  The development of acidity is related to high soil concentrations of acidic cations, like hydrogen (H+) and aluminium (Al+++) in the soil.  Acidification can be caused by accumulation of soil organic matter, nitrogen fixation, leaching of nitrate and fertiliser application.  Crop harvesting can also cause soil acidity.  Crops absorb elements from the soil for plant growth.  When a crop is harvested, some of the soil elements that counter acidity development are removed; the net effect is an increase in soil acidity.  When soil pH is too high it can have serious implications for soil health and vegetation growth. 

Suggested indicator: Soil pH

Soil pH refers to the acidity or alkalinity of a soil.  It is measured on a scale of 0 to 14, with a pH of 7 denoting neutrality.  Higher pH values indicate alkalinity and lower values indicate acidity. 

Increased soil acidity may be associated with:
Potential associated impacts Suggested indicators

Reduced soil nutrient availability

  • Soil chemistry*
Reduced vegetation growth and shallow root depth, resulting in:
  • Increased deep drainage that rises watertable levels and subsequently increases salinity risks

Reduced ground and canopy cover leading to:

  • Increased potential for soil erosion
  • Ground cover
  • Shrub cover*
  • Tree canopy cover & health*
  • Organic litter*
  • Hillslope erosion*
  • Gully erosion*
  • Wind erosion*

 

Reduced water quality as a result of:

  • Increased water sediement and nutrient load due to erosion and soil leaching under acidic conditions
  • Reduced water pH due to seepage of acids into waterways
  • Fine sediment in water*
  • Phosphates in water*
  • Nitrates in water*
  • pH of water*

Reduced soil biota

  • Soil life*

*Yet to be developed

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