The experiment was conducted in a green house of Hirosaki University, Japan. Using stratified paddy field
model consisting of 50cm×30cm×70cm in size steel box filled with four layers of soil materials. Plow
layer (I layer; 0-12.5cm), plow sole (II layer; 12.5-22.5cm), upper subsoil (III layer; 22.5-57.5cm), and lower
subsoil (IV layer; 57.5-65.0cm) were constructed with Andosol (I layer), cadmium polluted soil (II
layer) ,gravel (III layer) and gravel with sand (IV layer). Stratified paddy field models were subjected to two
kinds of percolation pattern as an open system percolation and a closed system percolation. These two
percolation systems were imposed in paddy field models by controlling water level at 52.5cm and 7.5cm,
respectively using a subsurface drainage pipe. The ground water level in an open and a closed percolation
pattern was 52.5 and 7.5 cm, respectively. Platinum electrodes were placed in each soil layer to measure the
value of oxidation reduction potential in soil.