threatens grain output

Experts also argue that an increase in plant disease and the deterioration of the environment have been triggered, partly, by years of chemical fertilizer use.

"Farmers usually only care about crop output and income. They seldom consider the soil damage and potential risks to human health from overusing fertilizers," Li Shilin, director of the agricultural technical station in Anhui province's Fengtai county, said.

China uses 1.3 million tons of pesticides annually, with usage per unit area 2.5 times the global average, Zhang Weili, a CAAS professor on soil and fertilizer, told China Daily, citing official figures.

Also, the country's surface water pollution is grave while its seven major rivers and coastal waters are also polluted, a report by the Ministry of Environmental Protection said in June.

Of the 26 lakes and reservoirs under monitoring, 42.3 percent are "eutrophicated", a process that can lead to a proliferation of plant life caused by excessive levels of phosphorous and nitrogen, the report adds.

"China can no longer boost grain production by relying on agrochemicals," Zhang said.

Together with her colleagues at the CAAS, Zhang conducted a field investigation on the effects of agrochemicals on soil fertility across the country over the past 10 years.

"More cultivated land will face risks of greater yield decreases in the next few years since the soil is too fragile to withstand natural disasters, which will become more severe and longer due to climate change," she said.

Jiang, from the Academy of Sciences, highlighted the importance of government support.

"More subsidies are needed to support intensive cultivation, a traditional way to protect soil fertility. At present, almost no farmers are willing to do so because of higher costs in terms of time and money," he said.

Lu Bu, another CAAS professor, said farmers needed practical help.

"The government should encourage companies to help local farmers with intensive cultivation, such as providing advanced equipment that ordinary farmers cannot afford."