2000 Volume 84 Pages 13-22
Models of stratified paddy fields of Kuroboku soil were used and composed of 3 layers. These models were planted with rice and were fertilized. The models were used to investigate the relationship between the removal of soil solution element in percolation water and percolation patterns. Concentrations of nitrate, dissolved oxygen and redox potential in the open system percolation (subsoil) increased more than those in the closed one (plow layer and plowsole). Also, electric conductivity and the concentration of iron element and manganese element tended to invert. Potassium element provided from the conventional fertilizer increased. Potassium concentrations in both plow layer and plowsole was more than that of subsoil during the 50 days from the beginning of this test. After 50 days, the concentration of soil solution in all layers became similar. Concentrations of total nitrogen in the drainage of this model were higher than that of inundation during the first 50 days from the beginning of the test. Concentrations of total phosphorus had a similar tendency. But that tendency only continued for about 30 days. After 50 days, concentrations of total nitrogen in inundation became higher than those of drainage. After 30 days, cncentrations of total phosphorus in inundation bacame higher than those of drainage.
