There is a strong exchange between CO2 and CaCO3 in soil, especially
at high CO2 concentrations. Consequently, all biological activities in soil,
increasing CO2 concentration due to respiration, strongly stimulate
CaCO3 recrystallization and thus, accelerate the periods of pedogenic
carbonate formation. The highest CO2 concentration of 4% shortened
the complete (95%) recrystallization period of carbonates by a factor
of 10 to 100 compared to lower CO2 concentrations. The average carbonate
recrystallization increased with salinity (i.e., higher EC) but decreased
with pH. This at least partly explains the CO2 influx from the
atmosphere into the saline and alkaline soils of deserts and semideserts.