The soybean market has transitioned into "rationing mode" as tight global supplies and crop-stressing drought in Argentina have ignited the strongest soy market rally in years, Joe Stone, the head of Cargill Inc's agricultural supply chain, said on Wednesday.

"We are going to need to ration. The extent of how much we're going to need to ration is probably going to be a function of the weather that we see in Argentina," Stone said during a webinar hosted by the US Soybean Export Council.

He did not provide any details about how that rationing would occur.