So the fact that they were exporting food pre-WWI and starting soon after Communism fell and importing food during its Communist era doesn't show problems of agricultural efficiency under Communism?
If the world was only that simple. Basically, how much of that export was done by domestic farmers and not foreign-capital farms (meaning it had to be exported)? What kind of grains were exported? Could it be that because of over-exportating, people actually had less to eat than during the Soviet Era (in terms of per capita, not actual distribution). While I do not disagree with that there was inefficiency, simplistic reasons can lead to the wrong conclusions, even when looking at the same situation.
In short: Put more thought into what you're saying, especially when things are not that simple and there are many biased beliefs floating around.