Effects of Acidic Precipitation and Acidity on Soil Microbial Processes

摘要

Effects of oil acidity on microbial decomposition of organic matter and transformation of nitrogen in an acid forest soil were investigated. In the oak-leaf-amended pH-adjusted acid soils, CO sub 2 production in 14- and 150-day preincubated samples decreased by about 6 and 37%, respectively. In the control (unamended) acidified soils, reductions in CO sub 2 production of 14% in 14-day preincubated samples and 52% in 150-day samples were observed. Ammonia formation in the pH-adjusted acid soil was about 50% less than in the naturally acid soil. Increased rates of ammonification and nitrification were observed in the pH-adjusted neutral soil. Little autotrophic and heterotrophic nitrifying activity was detected in naturally acid and acidified forest soils. The rate of denitrification was rather slow in acid soils, and at greater acidities N sub 2 O was the predominant end product. The abundance of nitrogen-fixing free-living bacteria was very low in acidic and acidified forest soils, and nitrogen gains by asymbiotic bacterial fixation in an acid forest ecosystem may be insignificant. These results suggest that further acidification of acid forest soils by addition of sulfuric acid or by acid precipitation may lead to significant reductions in the leaf litter decomposition, ammonification, nitrification, and denitrification and thus reduce nutrient recycling in the forest ecosystem. (ERA citation 06:027760)