Effect of toposequences on geochemical mass balance and clay mineral formation in soils developed on basalt parent material under subhumid climate condition

Four soil toposequences served as the basis to calculate the accumulation of soil organic matter, transformation of pedogenic Fe and Al and net losses of the main elements (Ca, Mg, K, Na, Fe, Al, Mn and Si) by means of mass-balance calculations. Elemental losses due to deglaciation and exposure to the weathering environment were calculated. These mass balance calculations indicate that extensive mineral weathering resulted in significant leaching losses of Si, major base cations, and Al (particularly from the upper horizons). Dominant duration identified with mass-balance analysis include desilication and loss of bases.