I suggest you have a look at Southern Weekend published in early August, that is, the issue with Yi Lee's Immortality as its theme, in which there is a discussion on the issue of grain pricing.

I can also say one more thing here:

During the Zhu Rongji administration, the grain pricing mechanism in China was changed to complete liberalization and the minimum purchase price coexisted. That is to say, in principle, all grain purchases are naturally exercised by enterprises, and farmers and purchasers form a trading relationship. However, since then, food prices have gradually fallen, and farmers are miserable.

Around 2005 (it seems like this time or 2003), the state strengthened the minimum purchase price mechanism. Establish grain reserves and build a large number of national grain reserves throughout the country. One of the responsibilities of China Grain Storage is that when the market grain price is lower than the national minimum guidance price, China Grain Storage is responsible for purchasing the grain in the hands of farmers at the minimum guidance price. When the price is higher than the lowest price, the grain storage can be stopped.

Judging from the effect of these years, this method has indeed ensured that farmers get at least the benefits, and China Grain Reserve has also become the largest grain reserve merchant. However, since 2009, other major grain purchasers (mainly COFCO) began to buy at a price higher than that of China Grain Reserve, which set off a new revolution. Whether this change will lead to the change of the existing mechanism of the country is worthy of attention.

From what I said above, I guess you can guess that the grain and futures exchanges with the lowest guidance price are different. Moreover, the nominal price control of the country is the lower limit (although the upper limit is actually controlled), but futures trading is different from this-well, it is completely irrelevant. (Futures trading, trading is a forward contract, not a physical object)