抄録
The effects of soil dressing on the silicic acid supplying capacity of paddy field soil were invesitigated, and the results of invesitigation were summarized as follows.
1. Available silicic acid content of soil for dressing was very high compared to that of paddy field soil.
2. Elution patterns following the change of pH of extraction buffer and extraction capacity are different for soil for dressing and paddy field soil. This result suggest the difference in the forms of supplying source.
3. From the quantitative ratio of silicic acid and alumina which is eluted simultaneously, the form of supply source was assumed to be aluminosilicate, and results of calculation were as follows. SiO2 (Al2 03)i.52 for paddy field soil and SiO2 (Al203)o.» for soil for dressing.
4 . Effect of supplying silicic acid by soil dressing was large in test cultivation of paddy rice and amount of absorption of silicic acid was so large as 2—5 times compared to the plot without soil dressing.
5 . Easy solble silicic acid which is contained in soil for dressing is estimated to be migrated and accumlated in soil layer in soil excavation site.
6 . Based on the results of invesitigation of paddy field site, effect of silicic acid by soil dressing showed decrease following the passage of year, and its years of lasting was supposed to be about 10 years.
