2003 Fiscal Year Final Research Report Summary
Effect of the combinations of reduced tillage, biocide application and fertilization on crop, soil and agroecosystem.
| Project/Area Number |
13660014
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
作物学
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| Research Institution | The University of Tokyo |
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Principal Investigator |
NAKAMOTO Tomomi 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 (50180419)
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| Co-Investigator(Kenkyū-buntansha) |
OYAIZU Hiroshi The University of Tokyo, Graduate School of Agricultural and Life Sciences, Professor, 大学院・農学生命科学研究科, 教授 (70177301)
YAMAGISHI Jyunko 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)
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| Project Period (FY) |
2001 – 2003
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| Keywords | Reduced tillage / Crop productivity / Weeds / Soil organisms / Agroecosystem / Sustainability |
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| Research Abstract |
1.To evaluate the feasibility of conservation tillage in combination with reduced biocide and fertilization regimes, field experiments were conducted using conventional (CT) and reduced tillage (RT), with or without reduced biocide and fertilization regimes.
2.Root biomass and sugar yield of sugar beet did not differ with any combinations of conservation practices. Early crop growth of soybean and spring wheat was increased under RT, which indicated a better nutrient utilization. However, reduced fertilization could not supply as much nitrogen as conventional chemical fertilization especially in the combination with RT. Larger amount of long-term application of organic fertilization may be necessary under RT compared to the requirement under CT to compensate for lower race of nitrogen release from organic matter. The species richness and diversity index of weeds were higher under manure application. When combined with manure application, RI may offer the potential for increasing diversity by reducing the competitiveness of dominant species and facilitating establishment of new or minor species.
3.Switching of tillage methods, from RT to CT or vice versa, reduced weed biomass in winter cropping. Although many annual and perennial weed species in summer cropping tended to increase under RT, the most dominant species, Amaranthus retroflexus, responded to tillage inconsistently. Species diversity of winter weeds and that of summer weeds was higher under RT than under CT. The microbial biomass and the population densities of nematodes and mites were higher under RT. The alternation of CT with RI was discussed.
4.Spatial dependence appeared more frequently under CT than under RT. The origin of tillage-induced spatial dependence and its possible role in precision farming were discussed.
5.A substrate-induced respiration (SIR) method combined with selective inhibition for estimating the fungal and bacterial biomass of Andosols was developed.
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