diff --git a/app/controllers/quantities_controller.rb b/app/controllers/quantities_controller.rb
index 0e2bccb..4bba6fb 100644
--- a/app/controllers/quantities_controller.rb
+++ b/app/controllers/quantities_controller.rb
@@ -58,7 +58,8 @@ class QuantitiesController < ApplicationController
       :name,
       :description,
       :domain,
-      :parent_id
+      :parent_id,
+      :primary
     )
   end
 
diff --git a/app/views/quantities/_form.html.erb b/app/views/quantities/_form.html.erb
index ebe892c..1dad598 100644
--- a/app/views/quantities/_form.html.erb
+++ b/app/views/quantities/_form.html.erb
@@ -10,13 +10,17 @@
   <% end %>
   <p><%= f.text_field :name, size: 25, required: true %></p>
   <p><%= f.text_field :description, size: 200 %></p>
+  <p><%= f.check_box :primary %></p>
 </div>
 
 <%= javascript_tag do %>
   function domainChange() {
     $('[id^=parent_select_]').prop('disabled', true).hide();
+    $('[id^=parent_select_] select').attr('name', 'placeholder');
     $('[id=parent_select_'+$('#quantity_domain option:selected').val()+']')
       .prop('disabled', false).show();
+    $('[id=parent_select_'+$('#quantity_domain option:selected').val()+'] select')
+      .attr('name', 'quantity[parent_id]');
   }
   $('#quantity-form').on('click', '#quantity_domain', domainChange);
 
diff --git a/config/locales/en.yml b/config/locales/en.yml
index 97738e2..40c2969 100644
--- a/config/locales/en.yml
+++ b/config/locales/en.yml
@@ -10,6 +10,7 @@ en:
   field_nutrients: 'Nutrients:'
   field_domain: 'Domain'
   field_parent_quantity: 'Parent'
+  field_primary: 'Primary'
   field_shortname: 'Short name'
   button_primary: 'Primary'
   activerecord: