| Budget Amount *help |
¥3,900,000 (Direct Cost: ¥3,000,000、Indirect Cost: ¥900,000)
Fiscal Year 2014: ¥1,300,000 (Direct Cost: ¥1,000,000、Indirect Cost: ¥300,000)
Fiscal Year 2013: ¥1,300,000 (Direct Cost: ¥1,000,000、Indirect Cost: ¥300,000)
Fiscal Year 2012: ¥1,300,000 (Direct Cost: ¥1,000,000、Indirect Cost: ¥300,000)
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| Outline of Final Research Achievements |
The aim of this study was to elucidate the actual gross nitrification rate of forest soils using isotope tracer techniques, which could not be measured by conventional incubation approach. We proposed combined usage of the d18O of NO3- measurements of field water samples and the pool dilution method using 15N tracers. Experimental results at the University of Tokyo, Tanashi Forest showed that the d18O of NO3- decreased drastically at the organic litter layer and the surface part of mineral soil horizon. This indicated that the NO3- supplied by atmospheric deposition was rapidly immobilized and replaced by the NO3- produced by nitrifying microbes. The gross nitrification and immobilization rates measured using the pool dilution method evidenced the NO3- replacement processes consistently.
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