Depressed gross mineralization and immobilization of nitrogen and changes in microbial population in soil after heat treatment |
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| Authors: | Rikiya Nira Tomoyoshi Hashimoto |
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| Institution: | 1. Hokkaido National Agricultural Experiment Station , Memuro , 082 , Japan;2. Hokkaido National Agricultural Experiment Station , Memuro , 082 , Japan;3. Crop Production Division, Ministry of Agriculture, Forestry and Fisheries , Chiyoda-ku , Tokyo , 100 , Japan |
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| Abstract: | Partial sterilization causes a change in N mineralization in soil. An increase in the net rate of N mineralization was reported in soil with chloropicrin applied to it (Rovira 1976), and has been well known in soil fumigated with chloroform to measure the microbial biomass N (Jenkinson and Ladd 1981). The gross rate of N mineralization increased in soil inoculated with fresh soil following fumigation with chloroform (Shen et al. 1984). The increased rate of N mineralization has been attributed to the rapid decomposition of organisms killed by partial sterilization (Jenkinson 1966). On the other hand, Nira et al. (1996) reported that the application of a fumigant in a field depressed the gross rates of N mineralization and immobilization in spite of the increase in the net rate of N mineralization. These results suggested that the increase in the net rate of N mineralization by partial sterilization is presumably due to the change in the ratio of N mineralization to immobilization. However, the residues of a fumigant may depress gross N transformation in the field, because the residues may continue to influence microbial activity long after the original treatment (Jenkinson 1966). Some effects of partial sterilization without residues on gross N mineralization remain to be determined. |
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| Keywords: | microbial population l5N isotope dilution method N mineralization partial sterilization |
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