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[C-2.3 Effects of Acid Rain on Crops and Agricultural Environments]

[Contact Person]

Jiro Harada
Head, Division of Vegetation Science,
National Institute of Agro-Environmental Sciences,
Ministry of Agriculture, Forestry and Fisheries
3-1-1 Kannondai, Tsukuba, Ibaraki 305 Japan
Phone +81-298-38-8243, Fax +81-298-38-8199

[Total Budget for FY1990-1992]

23,906,000 Yen

[Abstract]

　Photosynthetic response of leaves to acid rain varied among plant species. Decrease of photosynthetic rate with acid rain was mainly based on the decrease of chlorophyll content of leaves. Dry weight in most crops except rice reduced with simulated acid rain in the case that its acidity was more than pH 3.0. The results suggest that current ambient levels of rain acidity in Japan may not affect the growth and yield of most crops. Experiment on the combined effect of ozone and acid rain on the visible injury of plants also supported this suggestion. Soil column leaching experiments with simulated acid rain revealed that exchangeable base is the major source of buffering capacity of soils, and Al dissolution occurs at less than 3% of base saturation. Influences of plant roots, soil respiration and percolation rate should be considered to estimate acid-base budget of soils. Acid neutralizing capacity(ANC) values of 51 irrigation water ranged from 139 to 2,135μeq/l. These values suggest a small probability of acidification in irrigation water.

[Key Words]

Acid rain, Photosynthesis, Indicator plant, Buffering capacity