They make an intriguing posse: about 160 "scouts" in jeans and muddy boots,
jumping out of cars with ropes in hand, plunging deep into corn (maize) and soyabean fields across the American Midwest.
They are not just farmers. They include commodity traders and hedge-fund managers.
Their quest: to predict this year's harvest by using ropes as a measure and counting, to the last ear of corn and soyabean pod, the yield in a given area.
"We have a really beautiful crop. I think this is going to be a record," says Ted Seifried,
a market strategist at Zaner Group, a commodities brokerage in Chicago, during a stop in Nebraska on August 21st.
The mud on his boots is a reassuring sign of ample moisture in the soil.
But when he gets back into the car with others on the Pro Farmer Midwest Crop Tour,
但当他和谷物评估机构Pro Farmer Midwest Crop Tour的其他人回到车里时，
the talk turns to darker subjects, such as trade tensions, collapsing currencies and what he calls the start of an "economic cold war" between America and China.
"While we're driving the 15-25 miles from field to field, we certainly have a lot to talk about.
By and large the American producer thinks the fight with China is just. But it's very much affecting the pocketbook."
From the midwestern farm belt to the commodity markets of Chicago, New York, London and Shanghai,
this is a tricky time to be producing and trading commodities. Americans may relish their stockmarkets soaring.
But a rising dollar, higher American interest rates, sliding emerging-market currencies and fears of a tariff-induced blow to exports to China
have taken a toll on commodity prices in recent months.