Carbonized rice hull: From waste to soil conditioner

Carbonized rice hull: From waste to soil conditioner
Annually, we throw away or burn 2.5 million (M) t of rice hull that accumulate from the milling of 13 M t of palay. However, this “waste material” can be converted into a soil conditioner and bioorganic fertilizer called carbonized rice hull (CRH).

A hydrophilic material made from the incomplete or partial burning of rice hull, CRH contains potassium, phosphorus, calcium, magnesium, and other microelements needed for growing crops like garlic.

As soil conditioner, CRH replenishes air and retains water in the soil. Because of the heat it undergoes, it is sterile and thus, free from pathogens. As such, it makes an excellent host for beneficial microorganisms, and an ingredient for bioorganic fertilizer.

Making CRH is easy. In a dry and level area, make a fire and cover it with an open type carbonizer. Put 12-14 sacks of rice hull around the carbonizer until the mound reaches the chimney at about 1 meter high. After 20-30 minutes, use a long-handled shovel to over turn the mound and move the rice hull from below to the top of the burning mound. When the rice hulls turn black, sprinkle with water to extinguish the fire. Do not over burn the rice hull as it will turn into ash. Cool the freshly made CRH, then place in a bag, seal and stock in a safe and dry place.

In growing garlic, apply 3-9 t/ha of CRH in the soil after sowing, then place a thin layer of rice straw mulch. Irrigate at 10 days interval for 30 days and every 15 days thereafter until 75 days after planting.

In a report submitted to PCARRD, researchers from the Philippine Rice Research Institute led by Noel D. Ganotisi said that the use of CRH improved soil moisture and garlic yields.

Before the scheduled irrigation of garlic, higher soil moisture content was observed in plots applied with 6 t/ha and 9 t/ha of CRH. The same amount of CRH produced high yields of 3.62 t/ha and 3.46 t/ha, although these yields were comparable to that obtained from plots applied with 3 t/ha of CRH.

Written by Ofelia F. Domingo, S&T Media Service

Thursday, 13 December 2007