A major problem for getting grain out of Ukraine by truck and rail is the EU bureaucratic paperwork, says this BBC report. For truck routes long waits at the border are common and queues can stretch as long as 25 kilometres or 16 miles. By rail the Ukraine rail system is wider than the EU's so that the grain has to be transferred for rail on the border.This can take as much as 30 days or 16 days. This is limiting the shipments say Ukraine farmers and most of it is at this time corn shipments.
For years Ukraine farmers were used to sending grain out through the port of Odessa on the Black Sea. This is now closed till negotiations lead to its opening or EU and the US finds some other way to do it.