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Sources of Acidity in Some Forested Udults
Author(s) -
Richter D. D.
Publication year - 1986
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj1986.03615995005000060040x
Subject(s) - leaching (pedology) , soil water , bicarbonate , soil ph , forest floor , soil acidification , cation exchange capacity , environmental chemistry , chemistry , environmental science , acid rain , soil science , organic chemistry
Three sources of soil acidity (bicarbonate leaching; base‐cation accumulation in aboveground wood, roots, and forest floor; and acid atmospheric deposition) were evaluated in relation to exchangeable acidity of three forested Udults in Tennessee. The Udults have low effective CEC (CEC e ), from 2.4 to 3.7 cmol c kg −1 . In the three soils, H + from bicarbonate leaching averaged 0.60 kmol c ha −1 yr −1 over 2 yr. In five forest stands, 30 to 80 yr in age, H + from accumulation of excess base (EB) cations [EB = (Ca + Mg + K) − (P + S)] in aboveground wood, roots, and forest floor averaged 1.11 kmol c ha −1 yr −1 . Atmospheric H + inputs, estimated from bulk precipitation, averaged 0.67 kmol c ha −1 yr −1 . Total deposition of atmospheric acidity to these eastern Tennessee forests is on the order of 1 kmol c ha −1 yr −1 . Variations in H + inputs were caused by annual differences in the hydrologic cycle and by stand differences due to nutrientcycling and soil‐chemistry effects. In these forest ecosystems, sources of soil acidity from annual bicarbonate leaching and cation accumulation appeared to exceed atmospheric inputs. Exchangeable acidity in the forested Udults was large compared with annual fluxes of acidity. In the upper 60 cm of the three soils, KCl‐exchangeable acidity ranged from 100 to 274 kmol c ha −1 , and BaCl 2 ‐TEA (trieth‐anolamine) acidity ranged from 505 to 820 kmol c ha −1 . Despite low precipitation pH and low soil CEC e , the additional H + from acid deposition has not caused significant alteration of soil acidity or base solution of these Udults.