Back in ST2:TWoK, there (still?) were problems with food supply in the Federation: Carol Marcus' solution was to create new fertile worlds. This presupposes that there would be logistics for hauling food from Genesis-created farming planets to the planets in need.
The "solution" would be no solution at all unless those logistics were plausible - basically meaning they already existed in at least some form and extent. We have seen nothing of the sort in the episodes and movies, though, all the transport ships being midgets that couldn't feed a small town even if making daily trips to a farm in the next star system. Even the robot ships hauling grain in TAS were tiny, supposedly moving superior genetic material rather than grain intended for consumption at the destination.
Naturally, Genesis could also create "farming worlds" within mere interplanetary distances of the worlds in need. Say, Luna could be turned to a big farm to feed Earth. But the logistics issues would still be significant, especially if transporters cannot reach all the way from Luna to Earth (although we have heard of emergency bailout transporters covering distances of that sort, in TNG "First Duty").
Personally, I think Marcus was selling snake oil and Genesis would have satisfied intellectual rather than physical hunger. But if Genesis was feasible for feeding starving worlds in the 23rd century, then Gault could be a breadbasket planet, too. Although again my personal interpretation is that Gault is a rural world, just like 97.6% of the colonies we ever see (setting it aside from colonies that actually have industries and produce exportable goods), rather than a world with significant farming exports.
Timo Saloniemi