BEIJING: China’s reserves of phosphorus, a key element for growing food, could be exhausted within the next 35 years if the country maintains its current production rate, a new study has found.
However, China could delay exhausting its phosphorus reserves by more than 20 years through improving agronomic use efficiency of the mineral to the average level of 80 percent in developed countries without impairing current crop yields, said the study, published this week in the US journal Proceedings of the National Academy of Sciences.
Zengwei Yuan of Nanjing University and colleagues modeled the phosphorous cycle in China since the 1600s and evaluated the mineral’s potential for eutrophication, which may lead to algal blooms, plant overcrowding and oxygen depletion.
They found China intensified its phosphorus mining, particularly during the last 60 years, to feed increasing populations and meet people’s demand for animal protein.
In 2012, China’s annual phosphorus extraction reached 12.5 million tons, accounting for more than 40 percent of the global phosphorus production, they said.
About 70 percent of the domestically exploited phosphorus was used to produce synthetic fertilizers.
The study revealed phosphorus over-application by Chinese farmers.
In 2012, China’s crop production saw an average use of 80 kilograms of phosphorus per hectare, more than double the figure that crops can generally assimilate and far higher than the average level of the developed countries.
Meanwhile, only 4 percent of natural phosphorus resources were eventually ingested by Chinese residents in 2012, slightly lower than the 5 percent in the United States.
The researchers also found China has become a net phosphorus exporter since 2003, exporting mainly phosphorus-containing chemicals such as fertilizers and pesticides, while importing crops, specifically soybeans from the US, Brazil and Argentina.
As a result, phosphorous accumulated rapidly in China’s surface waters and lands in the last decade.
