Microbial biomass and nitrogen transformations in surface soils strongly acidified by volcanic hydrogen sulfide deposition in Osorezan, Japan
Version of Record online: 1 MAR 2010
© 2010 Japanese Society of Soil Science and Plant Nutrition
Soil Science & Plant Nutrition
Volume 56, Issue 1, pages 123–132, February 2010
How to Cite
WATANABE, M., YAMAMURA, S., TAKAMATSU, T., KOSHIKAWA, M. K., HAYASHI, S., MURATA, T., SAITO, S. S., INUBUSHI, K. and SAKAMOTO, K. (2010), Microbial biomass and nitrogen transformations in surface soils strongly acidified by volcanic hydrogen sulfide deposition in Osorezan, Japan. Soil Science & Plant Nutrition, 56: 123–132. doi: 10.1111/j.1747-0765.2009.00438.x
- Issue online: 1 MAR 2010
- Version of Record online: 1 MAR 2010
- Received 1 June 2009. Accepted for publication 2 December 2009.
- microbial biomass;
- nitrogen mineralization;
- volcanic acid deposition
Volcanic acidification has created unique ecosystems that have had to adapt to the acidic environments in volcanic regions. To characterize the primary microbial properties of strongly acidified soils in such environments, we investigated microbial biomass, nitrogen transformations and other relevant chemical properties in the surface soils of solfatara and forests from Osorezan, a typical volcanic region in Japan, and compared the results to common Japanese forest soils. Soil microbial biomass C (MBC) and N (MBN) were determined using the chloroform fumigation–extraction method. Potential net N mineralization and net nitrification were measured in aerobic laboratory incubations. Long-term acidification in the Osorezan soils by volcanic hydrogen sulfide deposition caused low soil pH (3.0–3.8), base cation deficiency and increased concentrations of toxic ions such as Al3+. The proportions of MBC to total carbon (MBC/TC ratio) and MBN to total nitrogen (MBN/TN ratio) were lower than those in common Japanese forest soils. The extreme acidic conditions may have inhibited microbial survival in the Osorezan acid soils. Net N mineralization occurred at rates comparable to those in common Cryptomeria japonica forest soils, probably because of the presence of acid-tolerant soil microorganisms. Net nitrification was completely inhibited and autotrophic ammonia oxidizers were not detected by the MPN method. The inhibition of nitrification prevents nitrogen leaching from the soils, thus maintaining a nitrogen cycle in the volcanic acid region in which (and NH3) is recycled among microorganisms and plants.