Abstract
The dissolution of silica in soil in rotational paddy fields and the assessment of a new variant of the surface water dissolution (SWD) method were examined. 1) The silica dissolution patterns by the usual method had a lower curve than that by SWD method. It is considered that the dissolution of silica into surface water by SWD method was not inhibited. It is concluded that the silica dissolution patterns can be estimated by using the SWD method. 2) The silica dissolution patterns in rotational paddy fields had a higher curve than that in non-rotational paddy fields. It was found that the silica dissolution patterns can be approximated by an exponential equation model. 3) It was suggested that the amounts of silica dissolution from transplanting to maturing time was little influenced by the fluctuation in temperature in the growing period. It is concluded that the silica dissolution patterns can be estimated by using an exponential equation model at 30℃ irrespective of the soil type. 4) The amount of silica, estimated from the silica dissolution model of soil and the water supply pattern, were close to the amounts of silica uptake by rice plant except in the initial stage. The amounts of silica uptake by rice plant on rotational paddy fields were higher than that on non-rotational paddy fields. It is concluded that the silica dissolution patterns on rotational paddy fields can be estimated by using the SWD method.
