Reprinted with permission from Asian Vegetable Research and Development Center, P.O. Box 205, Taipei
A planting mix for seedlings must promote good growth and provide sufficient nutrients, water and air to the plant roots.
Ordinary rice hulls make a poor material for this purpose, but smoked rice hull is an excellent one. The benefits of smoked rice hull are: it provides a bacteria and fungus-free material, it has good water-holding ability, it holds its shape for a long time, and it can supply nutrients to the plant.
Smoked rice hull (or husk) is fairly easy to prepare if you
follow the simple steps outlined.
- Materials needed are a metal or tile pipe 10 centimeters in diameter and 1-1.5 meters in length, some mediumsize stones or bricks, charcoal, and a quantity of dry rice hull.
- Position the pipe upright atop the stones or bricks. You may use the stones or bricks to support the pipe.
- Place charcoal around the base of the pipe, and start burning it. The pipe will maintain a source of air to the burning charcoal. This will provide an even distribution of heat among the rice hulls when they are added.
- Once the charcoal is burning, place some dry rice hull around it. Do not put too much hull at once; add the hull slowly at short intervals as the charcoal burns and the heap heats up.
- When the rice hull begins to blacken, the charcoal is hot enough to build a mound of dry rice hull around the pipe. Continue adding hull until it reaches the top of the pipe.
- Let natural carbonization take place; the rice hulls should not be allowed to burn but only carbonize.
- Watch the process closely. The outside of the pile will change from a yellowish color to brown and then to black. Once the outside of the mound turns black the carbonization process is complete.
- Spread the smoked rice hull on the ground to cool for 2 to 3 hours. Also get rid of any materials that have turned to ash by washing.
- To keep the pH at the proper level, mix 1 g of calcium superphosphate for each liter of smoked rice hull.
Now the smoked rice hull is ready for use as a planting medium to grow seedlings.