Gardening and agriculture can be the subject of academic study, but are also practiced by gardeners and farmers who don't necessarily take an academic approach.
Gardening and agriculture are highly dependent on geography, climate and bio-region
There are federal, state and local government agencies with a mission to support agriculture and food security.
Look for activist groups that support or oppose various gardening and agricultural practices (for example, urban chickens, front yard gardens, GMO crops, community supported agriculture, etc...).
In the U.S., Land grant colleges or agricultural colleges teach and study agriculture. These colleges offer cooperative extension services that publish agricultural information specific to local conditions.