MANILA, Philippines -- The government has to rethink the over-reliance on pesticides and chemical fertilizers in its agriculture to stem the negative effects on the environment, especially water sources, the Greenpeace environmental group said Friday.

Decades of agrochemical use has polluted water sources in the country and is directly posing risks to human health, Greepeace said yesterday at the launch of a new study, “Agrochemical use in the Philippines and its consequences to the environment.”

The report said the massive increase in the use of synthetic chemicals in agriculture since the 1960s has not resulted in a similar increase in crop yields but has instead caused substantial damage to the country’s water sources.

Drinking water contaminated by fertilizer has been found on a number of farms in the northern Philippines, Greenpeace said.

Groundwater analysis conducted by Greenpeace scientists found 30 percent of artesian wells tested in Benguet and Bulacan provinces in Luzon had nitrate levels above the World Health Organization safety threshold, the group said in a statement.

It also found high levels of nitrates around sweet pepper farms in Mangnuang, a village in Ilocos Norte.

The group said it was caused by nitrogen-based fertilizer runoff, which poses health risks, especially to children.

Nitrogen-based fertilizer runoff has been identified as a cause of toxic algal blooms, such as red tide, in water bodies, it said,

Previous studies conducted by other scientists between 1995 and 1999 found pesticide residues in groundwater wells around other farming areas in Ilocos Norte in concentrations that exceeded European Union safety limits, Greenpeace said.

“Clearly there is a need to shift away from the current industrial agriculture system which promotes the reliance on agrochemicals while neglecting to consider their negative effects on human health, the environment and the economy of local communities,” the group said.

Greenpeace campaigner Daniel Ocampo urged the government to institute programs to reduce agrochemical dependence in the country’s farms.

He said government should phase out subsidies for fertilizer and focus instead on assisting farmers in converting to ecological and sustainable farming methods.

Greenpeace noted that while the National Economic and Development Authority has stated that 37 percent of water pollution in the country originates from agricultural practices which include animal waste and fertilizer and pesticide runoff, the government has made no effort to reduce agrochemical use.

The report said that the massive increase in the use of fertilizers in the past few decades has not resulted in higher crop yields.

While there has been a 1,000 percent increase in fertilizer use over the past 44 years since 1961, rice and corn yields only registered an increase of 200 percent and 280 percent, respectively, Greenpeace said.

Pesticide use from 1977 to 1987 increased by 325 percent, but rice yield went up by only 30 percent.

“There are proven low-cost alternatives to expensive chemical agriculture systems: farmers are already fertilizing soils and protecting crops with organic and sustainable techniques that work with nature, not against it, and which can provide food for all without compromising land and water resources,” said Ocampo.