Role of Soil Organic Matter in the Effect of Acid Rain on Nitrogen Mineralization
1986
Stroo, Hans F. | Alexander, Martin
The effect of soil organic matter on the influence of acid rain on microbial processes was studied in columns containing samples from the O horizons of two forest soils and mixtures of those horizons with sand. Simulated acid rain at pH 3.5 reduced the percentage of inorganic N present as NO⁻₃ when the organic matter level was below about 0.1 g/g soil, and the percentage decreased with decreasing organic matter levels. The effects of acid rain on N mineralization and NO⁻₃ formation in Adams (Typic Haplorthods) soil were similar. Nitrogen mineralization was increased in Croghan (Aquic Haplorthods) soil by simulated acid rain when the organic matter content was high, and the degree of stimulation decreased with lower organic matter levels. Dissolved organic C levels were initially decreased by treatment with simulated acid rain in all soil mixtures, but the amounts in soil solutions from acid rain-treated soils recovered with time to similar or greater levels than in the control soils. The recovery was more rapid in Croghan than Adams soil. Increasing organic matter contents in soil mixtures also decreased the magnitude and duration of acid rain-induced changes in pH of soil solution and levels of dissolved organic C.
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