China had an outsized affect on comkodity demand, at the same time capacity has been over built for many years. For oil, obviously the US resurgence has been a huge factor, and for food crops they had a couple of very very good years globally (and new land has been brought online).

Several currencies are sliding down against the USD (for a variety of reasons).

Food crops may be good but food prices are the first thing to spike when inflation spikes, and many nations have seen food prices climb ~20% across the board without parallel increases in wages and salaries. This is not good.

A stronger dollar combined with a lack of a middle-class that can actually use the dollar's strength to consume more stuff means trouble.

A stronger dollar is what destroys the middle class by crushing exports: http://www.tradingeconomics.com/united-states/balance-of-tra... (click MAX)

http://www.usatoday.com/story/money/business/2015/05/05/trad...

Perhaps worse for people in the US than a potential drop in exports (we've had a negative balance of trade for a while, irrespective of dollar strength) is the effect on corporate earnings for US companies that make money abroad. A strong dollar wreaks havoc on their balance sheets (since they need to report their earnings in dollars) and can absolutely lead to falling share prices as well as domestic job cuts.