China holds huge, mostly secret, stockpiles of basic commodities and sometimes doesn’t know what to do with them. Accounting rules prevent authorities from selling at a loss, so they may bend rules or restrict imports to make sales possible. Some of China’s stored corn is three years old and feared to be moldy. The government is preparing to sell a large amount of it without disclosing the volume or the buyers. Supposedly the corn will go to manufacture basic industrial material such as starch and ethanol, but there are fears that some of it might secretly end up in industrial food products such as corn syrup and corn starch. There are similar, if less serious, problems with selling old rice. Meanwhile, global cotton prices are holding steady in spite of dry weather in key growing areas because of the expectation that China will temporarily bar cotton imports in order to sell off parts of its huge cotton stockpile.
It is a different story with copper, which China is buying to guard against future price increases on the global market. Copper stockpiles can be estimated with some confidence because most of it is registered with exchanges. For the first time that anyone can remember, China has the largest stockpile of finished copper in the world.