Question

Discuss or show how soils buffer attempts to increase soil pH.

Answer 1

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Soil pH is a measure of the acidity or basicity of a soil. In soils, it is measured in a slurry of soil mixed with water and normally falls between 3 and 10, with 7 being neutral. Acid soils have a pH below 7 and alkaline soils have a pH above 7.

As we all know, soil itself is a buffer system. If added some acid solution, soil will buffer and slow down decline of soil pH. And soil pH might be unstable after addition of acid solution for some period.Buffering Capacity is the ability of the soil to re-supply an ion to the soil solution.In order to produce a certain change of pH, it is usually necessary to add much more acid or alkali than the amount of H⁺ and OH^– ions present in the soil suspension.

Keeping all other factors constant, the buffering capacity of a soil increased with increasing cation exchange capacity of a soil (CEC). Soils containing large amounts of calcium carbonate, organic acids and phosphates show higher buffering capacity. The greater the buffering capacity of the soil, the larger must be the amounts of lime or sulphur to affect a given change in pH. An abrupt change in pH causes a radical modification in soil environment and if it fluctuates too widely, the plants and microorganisms would suffer seriously.