ABSTRACT
The supply of nutrients to plants and crops is a natural process of silicate mineral weathering and is coupled to parallel processes that ‹x atmospheric CO2 as soil carbonate minerals. In this chapter, evidence is reviewed that allows estimation of the rates at which these processes take place, showing that they can be rapid on a human time scale. For example, in certain urban soils, the measured rate of removal of CO2 is 12.5 t/ha/month, through the precipitation of calcium carbonate. Similarly, the oxidation of compost and soil organic matter leads rapidly to the formation of calcium carbonate in arti‹cial soils. The ability of silicate minerals in soils to supply plant nutrients has been demonstrated in a number of studies and relies on the interaction between the kinetics of mineral dissolution and reaction with plant root exudates. Both nutrient supply and carbon capture through carbonate precipitation are coupled reactions; however, their bene‹ts do not necessarily occur in the same location within a soil horizon.
