Onion farm applied with VAM

The use of Vesicular Arbuscular Mycorhizae or VAM, a fungus, as a biological fertilizer reduces chemical fertilizer use by 60 to 80 percent.

According to Herminia Rapusas of DA-PhilRice, who leads the project Enhancing the Implementation of the Integrated Pest Management, VAM is a symbiotic association of a beneficial fungus and a plant. The fungus penetrates the root system of a crop such as onion, tomato, and eggplant; helps protect the crops from soil-borne pathogens; and improves the crop’s absorption of resources such as nutrients and water from the soil.

The use of VAM as biofertilizer was developed by the National Institute of Molecular Biology and Biotechnology of the University of the Philippines-Los Baños while the Integrated Pest Management-Collaborative Research Support Program (IPM-CRSP) with DA-PhilRice promoted the fungus as a good alternative to commercial fertilizers.  

One of the graduates from the season-long farmers’ field school (FFS) on IPM, 30-year-old Rodel Corpuz of Sinait, Ilocos Sur testified to the advantages of using VAM in his 0.25 ha onion farm. Corpuz said that before, he used to spend P5,000. Now, he only spends P2,000 for he reduces chemical fertilizer use. Thus, the technology helps vegetable farmers save on production cost. Being free of chemicals, VAM is also safe to humans and the environment.

Corpuz has been using VAM for three cropping seasons. He observes that apart from cost reduction, healthier seedlings with higher percentage of survival and resistance to plant diseases are produced.

Jose Ducusin, 56, of Narvacan, Ilocos Sur, also an FFS participant, said that although it is hard to produce VAM inoculants, it is worth the effort. He starts to completely do away with commercial fertilizer. He used to apply 10 bags of fertilizer a hectare in his onion farm. Now, he only uses VAM.

“Thanks to DA-PhilRice, we may never know that this technology exists without them teaching us how to produce and apply VAM in our fields,” Ducusin said.

So, how do we produce and apply VAM root inoculant?   

VAM root inoculants are cut dried roots of matured corn inoculated with VAM at seeding. During harvest, soil adhering on the corn roots is removed and the roots are cut into small pieces to become VAM root inoculant.

VAM root inoculant production. Sterilize soil by heating for two to four hours using a big pan or “kawa” or by drying under the intense heat of the sun for two to three days.

Place the sterilized soil in thoroughly cleaned and dry clay pots. After cooling the soil, place a pinch of root starter inoculant and then cover it with a thin layer of soil. Sow three to five native corn seeds in each pot.

Allow the plants to grow for three months under normal conditions. Protect the plants from pests and diseases. Stop watering the plants after three months. Cut the plants or stalks when they are completely dried. Allow the soil in the pot to dry further.

Remove soil adhering to the roots. Cut the roots finely and save some root inoculants for future use. Mix the finely cut roots with the soil from the pot to produce VAM soil inoculants. Store the root and soil inoculants in sealed plastic bags in a dry and cold place (i.e. refrigerator).

VAM application in seedbed. Do not use chemical fertilizer on seedbed before sowing if VAM is to be applied. Broadcast VAM soil inoculant thinly on prepared seedbed. Cover VAM soil inoculant with a thin layer of soil. Sow seeds on the seedbed with VAM. Cover the seeds with a thin layer of soil. If necessary, apply fertilizer 15 days after sowing.

For more information, write, visit, or call the Integrated Pest Management-Collaborative Research and Support Program at the Philippine Rice Research Institute, Maligaya, Science City of Muñoz, Nueva Ecija with telephone numbers (044) 456-0285; -0113; -0651 local 221. You may also refer to PhilRice’s technology bulletin titled “Biofertilizer Production: Vesicular Arbuscular Mycorrhizae (VAM).”