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Green fertilizers to curb pollution

— Photo: AFP

A dead fish floats on the once scenic Taihu lake, hit by an outbreak of blue-green algae in this May file photo.

JINAN (CHINA): Chinese scientists are encouraging farmers to use controlled release compound fertilisers to curb nutrients runoff and protect the environment in the wake of major algae bloom outbreaks believed mainly to be caused by run-off from heavy fertilizer use.

China is home to only 7 per cent of the world’s farmland, but its fertilizer consumption accounted for more than 35 per cent of the world’s total, said Feng Yuanqi, a senior expert on chemistry.

Nitrogen, phosphorus and potassium fertilizers are frequently overused and misused, and a large quantity of fertilizers are lost to leaching and evaporation, said Mr. Feng. Only 30-35 per cent of the nitrogen fertilizers applied to farmland played a role in helping crops grow and the ratios were 15-20 per cent and no more than 65 per cent for phosphorus and potassium fertilizers respectively, according to Shi Yuanliang, who has been engaged in development of new fertilisers.

The runoff of nutrients from chemical fertilizers not only increased the cost of farming and caused waste of resources; it also brought huge pressure for the environmental protection effort.

For nitrogen fertilizers alone, statistics show, 14 million tonnes of nitrogen, valued at $6.6 billion, are lost to leaching and evaporation every year in China. Over the past several months, the nutrient runoffs and other pollutants caused blue-green algae to bloom in China’s major lakes.

However, China has to produce enough grain to feed its population of 1.3 billion, and the key to a greater grain output lies in fertilizers, said Mr. Feng.

As it is hard to curb the heavy use of fertilizers, Chinese sciences and agricultural workers have developed fertilizers that are environment-friendly, including the controlled release fertilizers that allow the nutrients to be released at a slower rate throughout the growing period. — Xinhua

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