"China has succeeded in producing one fourth of world’s grain and feeding one fifth of world’s population with less than 10 percent of the world’s arable land. This is not only a great achievement in the pursuit of food and nutrition security in China itself, but also globally. Currently, China ranks first in the world in terms of the production of cereals, cotton, fruits, vegetables, meat, poultry, eggs and fish".
China is ranked #1 in the world in agricultural production.
You bring up some great points, and I know all of the agricultural production is subsidized by the government, so if their economy crashes, so will their agricultural outputs.