| Matschonat, G; Matzner, E: Quantification of ammonium sorption in acid forest soils by sorption isotherms, Plant and Soil, 168-169, 95-101 (1995) | |
| Abstract: Quantity/Intensity relations of NH4+ were established to evaluate the role of NH + sorption as a N-sink as well as for the transport of NH + within the soil profile. Two haplic podzols (originating from Phyllite and Granite) from the German Fichtelgebirge were used. Exchange isotherms were obtained from batch experiments with NH4+ concentrations between 0.01 to 0.6 mmol NH4+ L -l. Background solutions had a composition close to the natural soil solutions to identify the cations displaced by NH +. Organic layers sorbed a maximum amount of 0.3-0.5 mmolc NH4 + 100 g-l, A horizons 0.1-0.2 mmolc NH4 + 100 g-1 and B horizons 0.09 mmolc 100 g-l, corresponding to less than 1% of the cation exchange capacities. NH4 + displaced K + and Ca 2+ throughout the whole profile, and additionally A1 in the subsoil horizons and H30 + in the organic and A horizons. "Initial mass isotherms" (Quantity/Quantity isotherms) were established with distribution coefficients ranging from 0.17 to 0.35 for NH4+ with highest values in the O horizons. While exchangeable NH4+ in acid forest soils is considered to be only a minor long-term sink for deposited NH4+ , it has its relevance in the seasonal dynamics and transport ofNH4+ |
