Aggregates are created through a number of ways, including freezing and thawing, wetting
and drying, fungal activity, tillage, and by plant roots that surround the soil and separate the
clumps. Weak aggregates are cemented to make them distinct and strong. Clay, iron oxides,and organic matter often act as cements. When soil microorganisms break down plant residues,
gums are produced that glue peds together.