Aluminum toxicity of soil

ALUMINUM TOXICITY

Aluminum toxicity can occur in soils that have large amounts of aluminum containing minerals. In such soils, aluminum can dissolve into the soil solution as the soil pH drops below 5.4. In contrast, aluminum solubility decreases dramatically as the soil pH increases above 5.4. As a result, proper management of soil pH can prevent problems associated with aluminum toxicity.

• Excessive amounts of aluminum can inhibit root development and limit crop growth.
• Aluminum saturation is an expression which describes the relative abundance of aluminum in the soil.
  • Like base saturation, aluminum saturation is the percentage of the CEC occupies by aluminum. Like all cations, aluminum held by the cation exchange complex is in equilibrium with aluminum in the soil solution.
  • Although the tolerance to aluminum varies among plant species, most plants do not tolerate greater than 15% aluminum saturation.
  • However, certain crops grown in Hawaii, such as sugarcane, pineapple, corn and ti, can tolerant relatively high levels of aluminum saturation.

Conditions that cause aluminum toxicity

Aluminum toxicity occurs readily under acidic conditions, especially when pH values are equal to or less than 5.4. In the acidic soils of the tropics, aluminum toxicity may become a serious problem and limit crop yield. Management of soil pH is the key factor in avoiding aluminum toxicities. Aluminum toxicity may be ameliorated by liming your fields.