How does pH affect plant growth?

1 Answer
Aug 4, 2015

Soil pH affects influences several factors that affect plant growth.


These factors include:

  • soil bacteria
  • nutrient leaching
  • nutrient availability
  • toxic elements

Soil pH

Soil Bacteria

  • Bacteria operate best in the pH range of 5.5 to 7.0.
  • A soil pH outside this range decreases their ability to release nitrogen from organic matter.

Nutrient Leaching

  • Calcium, nitrogen, potassium, magnesium, sodium, and sulfur rapidly leach out of soils at pH < 5.

Nutrient Availability

  • Phosphorus is never readily soluble in the soil, but it is most available around pH 6.5.
  • Low pH can induce deficiencies of micronutrients such as manganese, molybdenum, copper, and boron.

Toxic Elements

  • Aluminium, iron, and manganese may become toxic to plant growth below pH 5.