| Budget Amount *help |
¥3,600,000 (Direct Cost: ¥3,600,000)
Fiscal Year 1999: ¥800,000 (Direct Cost: ¥800,000)
Fiscal Year 1998: ¥2,800,000 (Direct Cost: ¥2,800,000)
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| Research Abstract |
Organic constituents in uncultivated (forest) and cultivated soils for major soil types in Hokkaido, I.e. wet type andosol, andosol, brown forest soil, gray terrace soil and alluvial soil. Investigated subjects include fundamental soil properties, humic substances in free and combined forms, soil saccharides of microbial and plant origin, phenolic compounds derived from lignin by CuO-NaOH oxidation, and easily decomposable nitrogeneous constituents. Organic matter constituents were also investigated in the soils under different land uses in the red acid soil area in South Sumatra, Indonesia, where clearing and bunring of the forest as well as the development of plantation agriculture are rapidly in progress. In result, it was clarified that land use as cultivated land brings about the severe exhaustion of humic substances and saccharine constituents both in the temperate and tropical zones. The amounts of easily decomposable organic matter which is represented by hot water extractable
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constituents, however, were similar between the temperate and tropical zones. Easily decomposable organic matter in the tropics may be supplied directly from the plant residue such as fallen leaves and twigs. It will be exhausted rapidly when vegetation is removed by man, because the stock of soil organic matter is scarce. Growing natural weeds on the ground of coffee plantation not only prevented the erosion of soils but also maintained the level of soil organic matter in the tropics. Agro-forestry such as the combination of leguminous tree and coffee tree increased the level of easily decomposable organic matter in the soil. Also in the temperate zone, exhaustion of soil organic matter in cultivated lands were demonstrated in andosols. Such exhaustion of soil organic matter will be a severe barrier for the sustainable agricultural production, development and practice of agricultural techniques are needed, so that the maintenance of soil organic matter in cultivate lands becomes possible. Less
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