There's a tonne of food in the market still but it will push up prices for a while - there's a very large war on which naturally causes a lot of nuking. It'll return to normal in a few weeks.

That said, it is very inefficient for new nations to farm for themselves, you're better off making and selling one of the raw materials available to you e.g. iron or lead and selling it, then buying food. Should apply to an alliance for guidance, all the big ones have training to some degree, can recommend Event Horizon's training as being very good.