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Salts and acids as determinants of the solution composition of acidic forest soils — anion effects
Author(s) -
Kaiser Klaus,
Kaupenjohann Martin
Publication year - 1998
Publication title -
zeitschrift für pflanzenernährung und bodenkunde
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.644
H-Index - 87
eISSN - 1522-2624
pISSN - 0044-3263
DOI - 10.1002/jpln.1998.3581610206
Subject(s) - chemistry , soil water , salt (chemistry) , composition (language) , topsoil , soil ph , base (topology) , sorption , inorganic chemistry , alkalinity , subsoil , nuclear chemistry , environmental chemistry , organic chemistry , adsorption , soil science , geology , mathematical analysis , linguistics , philosophy , mathematics
The study aimed at evaluating whether salt‐induced mobilization of acidity may be modified by the type of anion. For this purpose, the effects of different neutral salts on the solution composition of acid soils were investigated. The results were compared with those of the addition of acids. Two topsoil (E and A) and two subsoil horizons (Bs and Bw) were treated with NaCl, Na 2 SO 4 , MgCl 2 , MgSO 4 , HCl, and H 2 SO 4 at concentrations ranging from 0 to 10 mmol dm −3 . With increasing inputs of Cl − the pH of the equilibrium soil solution dropped, the concentrations of Al and Ca increased, and the molar Ca/(Al 3+ + AlOH 2+ + Al(OH) 2 + ) ratios decreased. These effects were the least pronounced when NaCl was added and the most at the HCl treatments. According to the release of acidity, the topsoils were more sensitive for salt‐induced soil solution acidification whereas on base of the molar Ca/(Al 3+ + AlOH 2+ + Al(OH) 2 + ) ratios, the salt effect seems to be more important for the subsoils. Addition of S0 4 2− salts and H 2 SO 4 induced higher pH and lower Al concentrations than the corresponding Cl − treatments due to the SO 4 2− sorption, especially in the subsoils. The Ca/(Al 3+ + AlOH 2+ + Al(OH) 2 + ) ratios were higher than those of the corresponding Cl − treatments. In subsoils even after H 2 SO 4 additions these ratios were not higher than those of the NaCl treatments. The results indicate (I) that speculation about the effects of episodic salt concentrations enhancement on soil solution acidification not only need to consider the ionic strength and the cation type but also the anion type, (II) that salt‐induced soil solution composition may be more crucial in subsoils than in topsoils, and (III) that in acid soils ongoing input of HNO 3 due to the precipitation load may induce an even more acidic soil solution than the inputs of H 2 SO 4 of the last decade.