China ramping up agricultural purchases to the level that the U.S. is demanding would be a problem and Beijing would probably only do it if the market situation warranted it, analysts said.

Their comments pour skepticism on the farm purchases that are part of the phase one trade deal recently announced by both countries.

Calling it a "crazy amount" of agricultural buying with "market distorting powers" on a global scale, Deborah Elms, executive director of the Asian Trade Centre, said: "The ramping up of scale at that speed is going to be problematic."

She told CNBC: "I would be willing to take a bet ... that we will be back at this table in relatively short order even if we get a deal, because the ability of the Chinese to actually match those purchases is going to be limited."

U.S. and Chinese officials announced on Friday that both countries finally reached an agreement after a contentious 18-month trade war. But as part of the deal, U.S. President Donald Trump insisted that China buy more U.S. crops, saying that Beijing will purchase $50 billion worth of agriculture goods "pretty soon." For his part, he vowed not to pursue a new round of tariffs originally set for the previous Sunday.

But Elms warned that the Chinese has been "very cautious" in saying that they would buy according to market conditions and World Trade Organization restrictions.

"In other words, there's a giant red flag that says: even if we promise this ... be careful because if the market doesn't support the purchases at that level, then we may not reach that target," she told CNBC on Monday.