buffering

This article only covers soil buffering. For chemical processes during buffering, see: Buffer (chemistry) ; for more general information on the subject see: Buffers

The buffering of a soil is its resistance to changes in the pH value when it is supplied with H ₃ O ⁺ or OH ^- ions. This resistance is important because plants and soil organisms react very sensitively to sudden changes in acidity . The buffering capacity of a soil is primarily determined by the cation exchange capacity and the base saturation of a soil. A sudden supply of H ₃ O ⁺ ions in the soil solution is neutralized by exchanging them for basic cations of the sorption complex . Conversely, a sudden supply of OH ^- ions is neutralized by releasing H ₃ O ⁺ ions into the soil solution in exchange for basic cations. The pH value therefore only changes significantly when the buffer capacity is exhausted. Because of the much higher amount of sorbed H ₃ O ⁺ ions, a soil with a high exchange capacity ( clay soil ) needs much larger amounts of lime to raise the pH value than a sandy soil with poor sorption . Calcareous soils have a very large buffering capacity against acids .

See also

• Buffer area (soil science)
• Exchange capacity
• Soil pH
• chemical soil properties
• Soil acidification