Sustainability concerns behind China's bumper harvest

He said farmers in his village are facing grave challenges in irrigation. "In the past, our wells were only 20 to 30 meters deep. But now, you won't see water unless you dig at least 50 meters underground."

While there is less and less irrigation water available, many water conservancy facilities are too old or poorly maintained to properly function, according to Liu Junwei, deputy head of the agriculture bureau of Shannxi's Baoji city.

In addition, the heavy use of chemical fertilizer for decades, intended to ensure yields, has trashed soil fertility and raised food safety risks, said Jiao Jiang, chief economist of the Heilongjiang Academy of Agricultural Sciences.

Official data shows China's arable land, accounting for less than 10 percent of the world's total, consumes over a third of the world's chemical fertilizer.

With water and land resources sparse, experts have said the government must put more effort into boosting farming productivity and efficiency.

The central authorities have taken action. A guideline issued in December 2013 said that by 2020, China will develop 53 million hectares of "high-standard" farmland, characterized by low use of water and fertilizer, high yields as well as drought and flood resistance.

Although the central government has long promoted water-efficient farming, the practice has been far from popular, due to farmers' low awareness and financial pressure on local governments, Li explained.

"Most major grain producing counties are not rich," he said, suggesting the central government spend more on helping local governments build advanced irrigation systems and revamp water conservancy facilities.

Ma Zhongming, deputy head of the Gansu Academy of Agricultural Sciences, said the government should promote wider use of manure and the practice of turning crop stalks into fertilizer to restore land fertility.

China produces about 700 million tons of crop stalks, which can serve as perfect fertilizer after being buried deep in soil, said Ma. "Chinese farmers were still adopting the method to enrich soil up to 30 years ago, but the tradition has largely been scrapped here today."

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