Flocculation refers to a process where soil elements are held together
Flocculation refers to a process during which soil particles dispersed in a solution contact and adhere each another, forming clusters, flocks, flakes, or clumps of a larger size.
The process of flocculation and stability of soil suspension is very important for soils. Stabble aggregates can be formed only in soils containing clay that will flocculate. If clay remains dispersed, the soil is puddled. Puddled soils are sticky when wet and hard when dry.
Root growth and soil aeration require a porous conditions in soils. If percolating rainwater leaches out elecrolytes from the soil, clay particles may become dispersed. As the soil becomes dry, caking or soil compaction may occur. The latter reduces the pore spaces, which inhibits soil aeration necessary for adequate root growth. Therefore, a flocculating concentration of electrolytes should be maintained in the soil.
To reach such a condition, the soil should be limed, although acidic soils are usually flocculated because of their high content of Aluminium, Iron and Magnesium. However, high Aluminium concentrations, though beneficial for flocculation of clay, are harmful for plant growth.
Calcium and Magnesium are also known to have high flocculation powers on the negatively charged clay particles and will reduce the toxic effect of high Aluminium concentrations.