| Silicon is an essential element for the development and yield of rice, so it is important to know the silicon supplying capacity (SSC) and fertilizer response of silicon in paddy soil. In order to explore the method for evaluating SSC of paddy soil, 15 soils in Liaoning region are selected, and field experiments, pot experiments, incubation experiments and chemical analyses are conducted. The effects of Si-fertilizer application on soil silicon fertility, others properties, silicon nutrition, and yield of rice are also discussed. The main conclusions drawn from the study are as follows:Lit is unable to evaluate SSC of paddy soil with 1M HAc-NaAc(pH4) method directly within wide pH range, because some unavailable silicon for plant can be extracted from soil which pH value are high. But it can be used for evaluating SSC of paddy soil after available silicon is calibrated by pH.2.In low silicon concentration conditions, the linear equation, y=bx-a , is found to be more suitable to describing silicon adsorption characteristics of all soils. There are correlations between parameter a, b, c (a/b) and soil properties, such as clay, pH, DCB-Fe. There is very significant exponential positive correlation between rice relative yield (RY) and a value. When RY is equal to 95%, the critical value of silicon deficiency level is 228mg.kg-1 (SiO2). Therefore, a value can be an index for evaluating SSC of paddy soil.3.Under flooded conditions, the liberation of silicon from soil can be expressed by y = kxm . There are correlations between parameters of equation and soil properties, for instance Fed/Feo, and Fed-Feo / Feo There is linear correlation between RY and accumulative silicon liberation amount in 60 days or silicon liberation initial velocity (km). When RY is equal to 95%, the critical value is 628mg.kg-1 (SiO2) in accumulative silicon liberation amount or 20mg.kg-1d-1 (SiO2) in km.4.KH2PO4-NaOH (pH6.5) buffer solution can be used for extracting availablesilicon in paddy soil. In the presence of 12 soils, there are significant positive correlations between the available silicon content extracted with this buffer solution and RY, accumulative silicon liberation amount in 60 days, and the available silicon are relative to clay, Fed-Feo/ Feo, active silicon and DCB-Si in soil.5.In the submerging conditions, the pH value is increased in acid soil and decreased in alkaline or weakly alkaline soil; finally the pH value is 6.4 to 7.5. The pH value can be increased in acid soil by application of Si-fertilizer and glucose, but there have no obvious effect in weakly alkaline and alkaline soil.6. In the submerging conditions, the Eh is decreased sharply firstly, and then is increased rapidly to a peak after the water is drawn. When the water is given, the Eh is decreased again. At some special stages, application of Si-fertilizer can increase Eh in acid soil; decrease in weakly alkaline and alkaline soil. The Eh of soil is decreased by application of glucose.7. In the submerging conditions, the silicon of soil solution (SSS) in all the treatments increases and reaches a peak, and then drops gradually. After that it is increased a little and followed by decreased in alkaline soil, but there are almost no rise in weakly alkaline and acid soil. At each stage, the order of SSS is: alkaline soil> weakly alkaline soil>acid soil. Contrast to the control, SSS in soil can be increased significantly by application of Si-fertilizer. The best result is from the combination of slag and glucose. The SSS during nutritive growth period can be increased after application of glucose, but the effect isn't obvious in reproductive period.8.In acid soil, the pH value was increased significantly by application of Si-fertilizer; at the same, the amount of the active silicon and amorphous silicon were promoted, and the amount of the soil water-soluble silicon was decreased, hi alkaline and weakly alkaline soil, amount of water-soluble silicon and available silicon were increased to some extent.9. hi the submerging conditions, th...
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