From Iowa State University website: (link)
Chad Hart: “This has been building over a long period of time, but this year will be a milestone. The United States has been the dominant producer of corn and soybeans for quite some time. For Brazil to ramp up dramatically and catch us, it shows the changing global conditions behind the crop markets.”
“The Brazilians will continue to build on their production base, while we’ve run out of room. About all the land we can devote to crop production is pretty much in already.”
China is somewhat reliant on food exports from the US and other Western countries, but decreasingly so. They are ramping up imports from South America to an extent I hadn’t realized until today.
From this old (Sept 2012) article I found: (link)
In 2010, 64% of Brazil’s soybean exports traveled to China, with the next largest supply being 6.1% to Spain, and then 5.8% to Germany.
For more detail, there’s this article specifically about Brazil-China soybean trade. It’s too technical for me but you might find it interesting – (link)