Stuttgart produces a great share, as the planet is basically owned by Synth Foods. During Rheinland's financial crisis, Liberty (and, mainly, Synth Foods) offered loans to Rheinland, in exchange for farming ground on Stuttgart, Rheinland's bread basket.
Step by step, Synth bought every inch on Stuttgart, pissing of the local Farmers, thus leading towards the creation of the LWB. They don't chase them for no reason.
Bottom line: Stuttgart should sell it.
Edit:
About 3. What bases/planets would consume it, if it existed?
Stations in outer space, as well as far-away planets with no real eco-system (Planet Harris, Planet Kurilen) since they depend on food rations (until now, food rations are the commodity transported by Synth Foods transports, I think)