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[C-3.2.1 Experimental Studies on the Evaluation of Critical Load in Soil-Plant Ecosystem]

[Contact Person]

Tsumugu Totsuka
Takeshi Izuta
Laboratory of Terrestrial Environment
Faculty of Agriculture
Tokyo University of Agriculture and Technology
Fuchu, Tokyo 183 Japan
Tel 81-423-67-5727, Fax +81-423-67-5728

[Total Budget for FY1993-1995]

9,000,000 Yen (FY1995 2,800,000 Yen)

[Abstract]

　Effects of soil acidification on dry weight growth of Japanese cedar seedlings(Cryptoleria japonica D.Don) were investigated in soils originated from different parent materials. Dry weight growth of the seedlings was supressed with increasing the amounts of H+ added for controlling the soil acidification. The growth reduction of the plants was greater in brown forest soil and red-yellow soil than in andosol when equal mounts of H⁺ were added to each soil. There was a highly negative correlation between the dry weight growth of the seedlings and the concentration of water-soluble Al in the soils. The threshold concentration of the mentioned Al for inducing growth reduction was 20μg/g(ppm). When the molar ratio of(Ca+Mg+K)/Al in brown forest soil(originated from granite) was lowered below 10, the dry weight growth was depressed, e.g. ca. 50% reduction at the ratio of 1.0.

[Key Words]

Acid Deposition, Brown Forest Soil, Soil Acidification, Cation Leaching, Japanese Cedar, Growth Effects