International trade wars are difficult. I get it. Yes it is complicated. Then there is data:
American farmers are titans of international commerce. From 2000 to 2017 the value of agricultural exports nearly tripled. Exports comprise more than a fifth of farm output. Grain gushes abroad in the highest volumes. As the world eats more meat, livestock producers need more animal feed, raising demand for soyabeans. Exports last year reached $21.6bn, more than double the value of corn, the next largest export.
These successes are due in part to government subsidies that incentivise production, such as farm payments that rise when commodity prices fall. These mainly support big operations: farms with incomes of $167,000 or more received nearly 70% of commodity payments in 2016, according to the Heritage Foundation, a think-tank.
Productivity-boosting measures have helped, too. Mr Sims, for instance, now uses data on yields to fine-tune the application of fertiliser. He flies drones to inspect crops for insect damage.
Farmers often coat seeds before planting to fend off rot and pests. Environmentalists worry about the impact on water and biodiversity. But production has boomed.
This has helped depress prices for corn and soyabeans in recent years, even as land, fertiliser and seed have remained relatively expensive.
So a trade war is particularly ill-timed.
Mr Trump announced tariffs on steel and aluminium imports in March, and extended them to Mexico, Canada and Europe in May. In retaliation Mexico, the second-largest importer of American pork by value, raised tariffs to 20%. China’s tariffs of up to 70% on pork, and 25% on soyabeans, hurt even more.
Mr Trump is due to meet Xi Jinping, China’s president, at the G20 summit later this month,