With the development of agriculture, soluble silicon content in the rice field is continuously decreasing. Without replenishing soluble silicon into the soil, rice yield cannot be increased. Replenishment of soluble silicon into the soil is also important in other cereal crops, vegetables and fruits.
In the past soluble silicon was replenished by applying slags from blast furnace and it has some disadvantages such as labor-intensiveness and geographical restrictions, i.e. Pyongyang has no iron works. In this thesis, we studied on substituting rhyolite tails from rhyolite mine clarification tank in Pyongyang for silicon fertilizer.
Silicon content of rhyolite is 70~95% and proper processing method converts rhyolite tails into a silicon fertilizer with high soluble silicon content. In this study, the baking condition, types and the amount of additives for increasing soluble silicon content were tested, and, also, the suitable application method of processed rhyolite tails was investigated in the field. The results showed that relevant baking temperature was 600~800℃ and the additives showed significant increase in soluble silicon content at the ratio of rhyolite tail: Calcium carbonate: lime potassium: MgCl2=1:0.2:0.1:0.05. At that time, the soluble silicon content was 12% and the content of mobile silicon amount was 11 832mg/100g. The processed rhyolite tail showed high efficiency when it was applied in the end of vegetative growth and the beginning of the reproductive growth and the application of 6kg of the processed rhyolite tail dissolved into water to 1 hectare of rice field was enough. When the processed rhyolite tail was applied, body silicon content of rice was increased, so it was enhanced anti-disease and insects, lodging resistance and affect on yield components the rice crop yield increased to 108%.
Study on the rhyolite processing method for increasing soluble silicon content and its application into rice needs further investigation and scientific exchange on an international level should be followed.
