2006 Fiscal Year Final Research Report Summary
Study on the soil ecosystem and its contribution to crop production in conservation tillage systems
| Project/Area Number |
16380013
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Crop science/Weed science
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| Research Institution | The University of Tokyo |
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Principal Investigator |
NAKAMOTO Tomomi The University of Tokyok, Graduate School of Agricultural and Life Sciences, Associate Professor, 大学院農学生命科学研究科, 助教授 (50180419)
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| Co-Investigator(Kenkyū-buntansha) |
YAMAGISHI Junko The University of Tokyo, Graduate School of Agricultural and Life Sciences, Associate Professor, 大学院農学生命科学研究科, 助教授 (60191219)
OYAIZU Hiroshi The University of Tokyo, Biotechnology Research Center, Professor, 生物生産工学研究センター, 教授 (70177301)
OKANO Seigo National Agriculture and Food National Organization, National Agricultural Research Center for Tohoku Region, Director, 生物系特定産業技術研究機構・東北農業研究センター, 業務科長 (50355335)
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| Project Period (FY) |
2004 – 2006
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| Keywords | conservation tillage / soil fauna / soil microorganisms / cover crop / no-tillage / litterbag / Andosols |
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| Research Abstract |
1. The following techniques were developed : (1) Two methods, the substrate induced respiration method and the microscopic method, were improved to estimate bacterial biomass and fungal biomass separately. (2) The population size of earthworms was assessed from their casts on the soil surface. Cumulative surface cast production was a good measure of earthworm biomass. (3) The litterbag method was improved. Cylindrical litterbags were used to determine the decomposition rate of plant residues.
2. The results from field studies were as follows : (1) The communities of soil organisms under the white clover living mulch were characterized by increased populations of organisms in the fungal pathway of organic matter decomposition and by a high population density of higher trophic groups. The higher litter decomposition rate in the living mulch plots suggested that the function of the detritus food web was enhanced under the living mulch system. (2) Studies on Andosols clarified that many faunal groups of soil organisms did not always have greater abundance or biomass in conservation tillage systems than in conventional tillage systems, although the activity of soil microbes was higher in conservation tillage systems. (3) The daily decay constant of litter in the surface soil layer was greater under no-tillage than under conventional tillage. It was considered that enchytraeids and earthworms contributed greatly to the decomposition. (4) No-tillage conducted in paddy rice fields increased the population density of nematodes.
3. As a rule, conservation practices, such as the use of cover crop and no-tillage, positive affect soil organisms. However, the response to the practices varied from faunal group to group. Further studies on a functional group of concern are needed to make efficient use of soil organisms for better crop production.
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