2/19/2012 08:08:00 PM
alasnews
The
effects of acid soil
Soils
with a pH of less than 7.0 are acid. The lower the pH, the more acid
the soil. When soil pH falls below 5.5, plant growth is affected.
Crop yields decrease, reducing productivity
Soils
provide water and nutrients for plant growth and development.
Essential plant nutrients include phosphorus, nitrogen, potassium and
sulfur. Plants require other elements such as molybdenum, in smaller
quantities. Some elements eg aluminium and manganese, are toxic to
plants.
Nutrients
become available to plants when they are dissolved in water. Plants
are able to take up phosphate, nitrate, potassium and sulfate ions in
solution.
The
solubility of nitients changes with pH. In acid soils (low pH),
molybdenum becomes less soluble and aluminium becomes more soluble.
Therefore, plant growth may be affected by either a deficiency of
molybdenum or too much aluminium.
Both
crop and pasture plants are affected by acid soils. there may be a
range of symptoms. Crops and pastures may be poorly established
resulting in patchy and uneven growth. Plant leaves may go yellow and
die at the tips. The root system of the plant may be stunted. Crops
may yield less.
Plants
vary in their sensitivity to low pH. Canola and lucerne are very
sensitive to acid soils so do not grow well. Lupins and triticale are
tolerant to soils of low pH so they still perform well.
Land
can become unproductive if acid soil is left untreated. Incorporating
lime into the soil raises the pH. Therefore, liming soil can reverse
the effects of acid soil on plants and return a paddock to
productivity.
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