| In the older Firefox versions, the location bar and the search bar could use two different search engines (eg. Google and Wikipedia). After Firefox 23, this was no longer possible.
You can setup firefox-keywords which allow you to put the keyword in front of the query like
which would invoke the google search engine.
You setup a keyword by going into the bookmarks manager (Show all bookmarks on some version) and adding a new bookmark and making sure that these two entries are as follows:
where the %s is inserting the query string into the URL
which means that Firefox will look for the g and use the Location you supplied.
After you set it up, it is wise to double-check the entry. Firefox may either not save it or overwrite with blank entries.