Update, 5/26: CME says the TAS will now be offered starting June 15 instead of the originally planned June 8, to ensure a smooth transition.
CME Group will begin 'trading at settlement' offering for ag futures on June 8 after closure of open-outcry, the company said in a brief Monday.
Related: CME Group plans closure for most futures trading pits
Trading at settlement is an order type that allows a market participant to buy or sell futures contracts during the trading day equal to the yet-to-be determined settlement price, or at a price up to four ticks above or below that price, CME explained.

According to CME Group, TAS will reduce uncertainty related to pricing around settlement; allow grain elevators and processors to price forward contracts at or near the settlement value; and will be a transparent alternative to floor based MOC orders, which will no longer be available after July 2.
TAS will be available for outrights and spreads and on CME Globex for grain, oilseed and livestock futures. Quotes will be published in real time on the screen throughout the trading day, and TAS order entry is not allowed prior to the beginning of each group's pre-open state, CME Group said.
More details on trading at settlement are available on the CME Group website.
Source: CME Group