in this case corn he was talking about--that dropped the price.

就像他说的这就导致了谷类价格下降
The farmers had to grow more to maintain their income,

由于农民耕种的作物单位面积收入在减少
because what they were growing was bringing less per bushel

加上农作物产量过高市场供大于求
because of the high, high yields that were out there,

所以农民不得不种植更多作物
and the market was being flooded with corn.

以此来维持生计
This led to even lower prices; that made food cheap,

这造成食品价格下降进而变得低廉
and the calories have to be sold.

这使得粮食必定卖出
And so what happens then is when the yields rise,

当产量上涨时
again Pollan is being quoted here,

这又要引用鲍兰的话
the market gets flooded with grain and its price collapses.

市场上粮食供应过多进而价格下滑
As a result there's a surfeit of cheap calories,

以至于有过量的廉价粮食
a clever market sooner or later

一个够精明的市场