Production of Slow-Release Type Fertilizer from Philippine Dolomitic Limestones and Rice Husks

　Philippine production of rice reached about 8.2 million tons in 1984, producting 1.6 million metric tons of waste rice husks. Although about half of this bulk is utilized as fuel, animal feed and poultry livestock beddings, the remaining half is just burned in the field and wasted, the disposal of which remains a major problem.
　The demand for fertilizers in agricultural countries particularly of the developing countries such as the Philippines, has in recent years been on the increasingly upward trend side by side with the increased need to maximize production of crops particularly rice. To fill this great demand, the production of fertilizers has been increased in many parts of the world. Studies are also being conducted with the end in view of improving the efficiency of fertilizers. Recent fertilizer technology reveals the advent of the slow-release type of fertilizer which has the unique characteristics of controlled nutrient release such that single fertilizer application results in sustained fertilization without danger of plasmolysis or fertilizer burns. The obvious advantages of this type of fertilizer includes savings on labor, reduced possibility of fertilizer burns and reduction in element losses through slow-release at a rate corresponding very nearly to the needs of the crop.