Use javascript by adding a Content Editor to the page or adding it to the markup itself. I did something similar, picked up ContactId from Query String. Picked up this code from [here][1] 

        <script src="https://ajax.googleapis.com/ajax/libs/jquery/1.11.3/jquery.min.js"></script>
        
        <script type="text/javascript">
        
        jQuery(document).ready(function($) {
        
            //get the Contact ID from they query string
            var contactId = getParameterByName("contactId");
            
            //Set the corresponding Lookup field value to the Contact ID
            $("select[title='Contact Name']").val(contactId);    
            
            //use this line to disable the lookup field selection
            $("select[title='Contact Name']").attr('disabled','disabled')
            
            //use this line to hide the lookup field and label entirely
            //$("select[title='Contact Name']").closest("tr").hide();            
        });
        
        function getParameterByName(name)
        {
          name = name.replace(/[\[]/, "\\\[").replace(/[\]]/, "\\\]");
          var regexS = "[\\?&]" + name + "=([^&#]*)";
          var regex = new RegExp(regexS);
          var results = regex.exec(window.location.href);
          if(results == null)
            return "";
          else
            return decodeURIComponent(results[1].replace(/\+/g, " "));
        }
        
        </script>

  [1]: http://summit7systems.com/creating-a-parentchild-list-relationship-in-sharepoint-2013/

Regards