Q. How is rice husk fertilizer made?

Answer

As a result of the high temperatures required to burn rice husks, the silicic acid that makes up more than 90% of the ash becomes insoluble, rendering the ash useless as a fertilizer. In contrast, the highly soluble amorphous silicic acid found in rice husks that have been burnt at low temperatures (about 500 degrees Celsius) can be used as a fertilizer. By increasing the level of silicic acid in the soil, this ash fertilizer helps paddy fields produce a bountiful crop of rice. The potential for efficient utilization of both heat energy and rice husk ashes is enhanced by this technique. After being burned as biomass fuel to produce power, the husks leave behind ashes that account for 20% of the material's initial volume, which presents a concern.