Larry White quotes the NYT and asks:
"Every year, nearly three million tons of harvested Mexican corn is left to rot because it is too expensive to sell."
How on earth could this be true? Does it mean that the mere cost of
transporting the corn from farm to market exceeds the market value of
the corn? (Seems impossible, given that Mexico pays prices that cover
the cost of importing corn from the US.) If so, why did anyone bother
to harvest the corn, and before that to grow it in the first place?
I would not vouch for Mexican government statistics. But I do know that large amounts of corn rot in rural Mexico. The corn is grown for immediate consumption. The rainfall is highly uncertain so farmers plant far more than they need to eat in a typical year. (Where is micro-insurance? But note the shadow value of family labor is often low, so why not plant more? Plus it keeps disputed claims to land active.) In most years there is a great deal of corn "waste," but the precautionary growing has some efficiency properties. The remaining corn is fed to the pigs or dogs or simply left to rot. There are relatively high fixed costs to entering more formal corn markets, most of all transporting the product (i.e., the police will demand bribes), plus the extra corn would not yield very much.
Few of these rural growers import corn from the United States. And it is not hard to believe that mass-shipped corn from the USA is cheaper in Chihuahua than corn shipped up from rural Guerrero.
Note also that many of the very poorest Mexicans grow corn for their own consumption and thus tariff-free corn importation from the US will expand their opportunity set; it will not "put them out of business."