CHICAGO (Reuters) -- The benchmark Chicago wheat futures contract heads into a pivotal phase on Wednesday with traders deeply divided over whether a new exchange storage rule will limit first-day deliveries against the July contract.

First notice day for deliveries against Chicago Board of Trade July agricultural futures comes just two days after the CBOT implemented its "variable storage rates" (VSR), a market mechanism to automatically raise or lower the price of storing deliverable wheat in order to bring cash and futures markets into alignment.

Several traders and analysts predicted light CBOT wheat deliveries of zero to 1,500 contracts. But ...