Acres USA is a monthly magazine focused on organic and sustainable farming practices. You'll find a wide variety of topics about production-scale farming oriented towards market gardeners, farmers, consultants, and ranchers.
Popular subject matter includes cover cropping, rotational grazing, soil fertility, composting, integrated pest management, alternative crops, government regulations, marketing, and finance.
Acres USA is a great resource if you want to learn about organic farming techniques - whether you're a market grower already or you just hope to become one in the future. Many of the tactics and principles in Acres USA are relevant for the home-scale permaculturist as well.