It's not just soybeans, China is dependent on importing food supplies from all over the planet. Especially meat, their dependence on livestock production from overseas dwarfs all other countries combined. They don't have enough arable land suitable for farming. Cut the imports from the USA and Brazil, and China has a huge problem trying to feed their populace.
There was a reason why rats were declared a “delicacy” during the days of Chairman Mao.