There are many definitions for agriculture. From my perspective I see a very distinct difference between the definition of a farmer and that of a consumer. Often times, in a consumers mind agriculture is a dirty word. It's associated with factory farming, "dangerous" pesticides and "big ag".
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As a member of the farming community agriculture means so much more to me. Agriculture is an inclusive term rather than exclusive. Agriculture is a term that touches every part of farming from sales to production of crops. It includes organic, conventional and everything in between. It touches livestock and crops. It covers food, fiber and "farmaseudicals".
To me, it can't be described by a bunch of words. It's a passion and excitement that I feel everyday in my line of work. A dictionary could never do justice to real agriculture. It can only be defined by speaking with a farmer and having him or her show you why they do what they do.