Abstract: The study investigated the effects of fertilization with different ratios of silicon and phosphorus fertilizers on the contents and bio\|availability of different phosphorus fractions in a paddy soil through pot experiment. Three levels of silicon and phosphate fertilizer treatments were carried out， i.e.， a total of nine treatments. The purpose of the study is to improve the phosphorus use efficiency in a paddy soil. The results showed that silicon and phosphorus fertilizers could have different impacts on different phosphorus fractions in the paddy soil. Slight to moderate silicon fertilizer applying could improve the efficiency of phosphate fertilizer， reduce the fixation of phosphorus in soil. However， high silicon with high phosphorus level （SihPh） might inhibit the activity of available phosphorus， decrease soil available phosphorus content， decrease plant phosphorus absorption， and reduce the transformation of other phosphorus forms to available phosphorus. The treatment of SimPh gained the fastest growth and highest grain yield.

Key words: silicon fertilizer, interaction, availability of phosphorus, paddy soil