The would exclude both Organic & Paid search traffic
For a test scenario where test is created to only be shown to SEM Organic search traffic. All that is needed is that on any page of your site where SEM traffic will be landing. Simply set up a Audience to Exclude traffic when the visitor lands with a particular URL parameter. This is typically the tracking ID of SEM Paid search campaigns but it can also be any text string inside the URL.
Yes, You can modify an existing audience or create a new audience in Adobe Target to Exclude Organic Traffic like below :
Please NOTE that the referring landing page is the page you clicked from to reach the current site this session. (For example, if you click an ad on Google and it leads you to the adobe.com home page, the referring landing page is google.com.)