Rooted plants also play a role in the weathering of materials at the surface of the earth. During photosynthesis, plants utilize the energy of the sun’s radiation to combine water and carbon dioxide and produce tissue necessary for growth and maintenance. Part of the hydrogen from moisture taken in by the plant is released at the surface of rootlets where it exchanged for ions of calcium, magnesium and sodium from adjacent particles of clay and other minerals.
These exchanged ions are required by the plant for nutrition. The hydrogen ions transferred to the clay particles render the play slightly acidic, and this triggers weathering reactions with neighbouring feldspars and other silicates. Eventually, some of these minerals also decompose to clay, thus perpetuating the weathering process.