diff --git a/ckanext/spatial/harvesters/base.py b/ckanext/spatial/harvesters/base.py
index 2d6aec7..017d722 100644
--- a/ckanext/spatial/harvesters/base.py
+++ b/ckanext/spatial/harvesters/base.py
@@ -673,7 +673,12 @@ class SpatialHarvester(HarvesterBase):
         '''
         if self._user_name:
             return self._user_name
-        self._site_user = p.toolkit.get_action('get_site_user')({'model': model, 'ignore_auth': True}, {})
+
+        context = {'model': model,
+                   'ignore_auth': True,
+                   'defer_commit': True, # See ckan/ckan#1714
+                  }
+        self._site_user = p.toolkit.get_action('get_site_user')(context, {})
 
         config_user_name = config.get('ckanext.spatial.harvest.user_name')
         if config_user_name: