Washington (CNN) President Donald Trump is upset with China for buying Brazilian soybeans instead of American ones amid the ongoing trade war, but the South American industry got its start thanks to an earlier round of protectionist policies under President Richard Nixon.

Nixon temporarily froze the prices of consumer goods and restricted exports of food in 1973 in response to rising inflation, a move that essentially cut off exports of US soybeans. It worked, creating a surplus and lowering prices for American consumers.

But the embargo -- which lasted for just three months -- prompted Brazil to step up its supply, particularly to Japan, creating a formidable competitor on the world agricultural stage and leaving a lasting impact on the American soybean industry.

"It inspired the Japanese to go look for somebody else and, basically, that action created the Brazilian soybean industry," said Andrew Novaković, a professor of agricultural economics at Cornell University.

Brazil nearly tripled its soybean production over the next decade, and growth continued as Japan made financial investments to help turn Brazil's wooded grasslands into a suitable place to grow soybeans -- a move that also accelerated deforestation in the country.