PhilRice scientists develop rice hull into plant inoculant

August 6, 2010 8:35 am 

By Danny O. Calleja

PILI, Camarines Sur, Aug. 5 – Bicol’s agricultural sector is elated by the latest technology developed by scientists of the Philippine Rice Research Institute (PhilRice) that makes out of carbonized rice hull (CRH) an environment-friendly carrier component in making microbial inoculants.

The use of microbial inoculants such as Rhizobium in crop production is now being widely adopted by farmers in Bicol as according to the Regional Field Unit (RFU) of the Department of Agriculture (DA) here has resulted in increased yield and added profit.

The new technology reduced by up to 50 percent the application of synthetic nitrogenous fertilizer, DA regional executive director for Bicol Marilyn Sta. Catalina said over the week.

The CRH inoculants technology was an undertaking of PhilRice scientists Constancio Asis Jr. and Julie Elijay based in the Science City of Muñoz, Nueva Ecija, she said.

In explaining about Rhizobium inoculants, Asis, in an article recently published on line by AgribusinessWeek was quoted as saying “the atmosphere has 78 percent nitrogen but this is in inert form which is not readily available for plant use due to the triple bond connecting the two nitrogen molecules,” says Asis.

At this point, he said that the use of Rhizobium inoculant can be beneficial because the bacterium Rhizobium releases nitrogenase, an enzyme that cuts the bond between nitrogen molecules, making it available to the plants.

In other words, nitrogenase helps in fixing atmospheric nitrogen and converting it into ammonia, a form which is usable by plants, according to Asis.

When used to inoculate seeds, by coating the seeds prior to planting, Rhizobium induces the formation of nodules on the roots of certain leguminous plants, and this bacterium in the nodules fixes the nitrogen for use by the plant, he said.

To utilize Rhizobium, it is often necessary to provide dependable inoculants to ensure effective nodulation of the inoculated leguminuous crops.

Asis said that the commercially available inoculants use wood charcoal as the carbon source for the Rhizobium inoculant carrier. Other components include garden soil, rice hull ash and ipil ipil leaves. However, they consider the use of wood charcoal as not so environment friendly as it contributes to the cutting of trees.

“That is the main reason why I and Dr. Elijay thought of replacing wood charcoal with carbonized rice hull because the latter is also a source of carbon and rice hull is abundant in the Philippines as a waste product in rice production,” he said.

“CRH can be produced using PhiRice-designed rice hull carbonizer which costs only P800 per unit,” Asis said.

While charcoal needs a grinder that consumes higher energy before these are made available as carrier component, CRH only requires lesser energy because these are easily broken down into smaller form, he added.

In their research titled “Use of Carbonized Rice Hull as Carrier Component of Rhizobium Inoculants,” Asis and Elijay directly substituted the wood charcoal with CRH. They used two treatments which are CRH and CRH-acidic soil carrier mixtures, according to Sta. Catalina.

The inoculant carrier components in each treatment were pulverized, sieved, mixed in plastic bags and sterilized. Then the Rhizobium broth culture was prepared and aseptically inoculated into the carrier mixtures at room temperature for 120 days.

The researchers, Sta. Catalina said, adopted the MPN (most probable number method) to determine the Rhizobium population.

From the results, the researchers concluded that the CRH-based mixtures were comparable to wood charcoal in maintaining the viability of Rhizobial cells. This was after the carrier mixtures met the acceptable standard of viable Rhizobia per gram of inoculant at 120 days after inoculation, she said.

In the same AgribusinessWeek article, Asis revealed that their next step would involve the introduction of the technology to the mixing plants of Rhizobium inoculants in strategically located areas in the country.

One very successfully adopted microbial inoculant locally is the Bio-N which is effective for use in rice, corn and vegetables. It is now being produced by a good number of farmer-cooperatives nationwide with the help of the National Institute of Molecular Biology and Biotechnology (BIOTECH) at the University of the Philippines-Los Baños, he said.

Asis and Elijay, the article said also plan to work on the extension of the storage life of Rhizobium inoculant with CRH carrier component up to six months to maximize its benefits.

Aside from reducing environmental impact, the researchers said that the use of CRH as a carrier component for Rhizobium inoculant results in a cheaper product as processing does not require much energy.

Sta. Catalina said, this new usage of CRH further make use of the 2.5 million metric tons of rice hull that accumulate from the milling palay all over the country. Earlier, this waste material had been converted into a soil conditioner and bioorganic fertilizer.

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.

CRH is also used to deodorize pigpens and its bio-activated version is effective in neutralizing odor of canals and speed up the decomposition of wastes.

This deodorizer was commercially developed into what is called now Fedgrozyme was introduced by Berlin trained industrial microbiologist Dr. Ronaldo Sumaoang who is also the president and CEO of the Novatech Group of Companies.

Fedgrozyme is manufactured by Novatech Vet and Biologicals, which also produces other veterinary and biological products.

According to Sumaoang, Fedgrozyme eliminates the odor of the manure by lessening the ammonia emitted by the manure.

Likewise, the protein that is still present in the manure continues to be degraded by Fedgrozyme microbial activity.

Fedgrozyme is actually a stabilized source of potent enzyme of microbial origin for animal use, and contains immobilized biological microorganisms, organic acids, vitamins, minerals, amino acids and phospholipids.

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 hull turns black, water is sprinkled to extinguish the fire to avoid over-burning that would turn the rice into ash.(PNA)

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