There are a few parameters that you can add to Soup URLs to filter what content to display:

Filtering by content type
Add ?type= followed by either text, link, quote, image, video, review, event, or file to your Soup's URL to show only posts of this content type.
Example: http://kitchen.soup.io/?type=quote

Filtering by date
Add ?date=YYYY-MM-DD to the URL to show posts on and before that date.
Example: http://kitchen.soup.io/?date=2008-06-01

Filtering by text search
Add ?search=query to the URL to show only posts that contain the text 'query'.
Example: http://kitchen.soup.io/?search=blog

To combine these filters, join them together with the & character.
Example: http://kitchen.soup.io/?type=quote&search=blog