SCIENCE CITY OF MUÑOZ, Philippines?Farmers were warned against using so-called micro-bearing biofertilizers following tests conducted by a science research agency that showed these substances do not increase yield as advertised.

The Philippine Rice Research Institute (PhilRice) said micro-bearing biofertilizers were falsely advertised.

?Biofertilizers are not effective in promoting growth and increasing rice and corn yield,? said Ronilo Beronio, PhilRice executive director, who cited tests conducted in 10 provinces that covered both wet and dry months.

Advocates claim that biofertilizers are microorganism-carrying substances that were designed to fix atmospheric nitrogen, add minerals and other nutrients to soil, produce growth-promoting hormones and serve as agents against pests and diseases.

Tests made in farms in Laguna, Isabela, Agusan, Bohol, Ilocos Norte, Negros Occidental, Leyte, Nueva Ecija, Samar and Camarines Sur tried to evaluate the substance?s effectiveness in irrigated and upland soil ecosystems.

?The perception that these materials are fertilizers has been debunked because they only provide small amount of nutrients, or not at all, required by high-yielding crops,? Beronio said.

?It cannot reduce the rate of usual inorganic fertilizer application by 50 percent and the cost of producing crops,? he added.

The study was conducted by Michelle Castillo and Cezar Mamaril, PhilRice science research specialist and senior consulting expert.

They conducted the study in collaboration with PhilRice branch stations, regional agencies of the Department of Agriculture, and state universities and colleges. Anselmo Roque, Inquirer Central Luzon