In the Mishna, Masechet Brachot is placed in Zeraim. But in the Shulchan Aruch, it is grouped with Shabbat and the holidays in Orach Chaim.
This reflects a different perception as to the place of brachot in our life. Grouping brachot with the holidays indicates that saying a bracha is a discrete observance which must be performed on certain occasions. Periodically you must keep shabbat, but you also know that the rest of the week cannot be shabbat.
Meanwhile, grouping brachot with zeraim indicates that saying a bracha is part of our normal life. It is not that you interrupt your farming in order to perform a religious observance (as with shabbat), but that saying the bracha is part of the farming, and gives the farming a religious character.
As part of the inexorable shift of religious practices from "natural/moral" to "ritual" over time (as circumstances change and the original rationale is left behind), brachot have changed from a natural part of our self-expression (in the Mishna) to a technical procedure that must be executed on specific occasions (in the Tur and Shulchan Aruch).
May that change someday, somehow reverse itself.
(Source for the good parts of this)