Perhaps you should try some spelling variations:
irrigation schemes » irrigation scheme, irrigation systems
integration volume » integration policy
group integration » grid integration, run integration, through integration
ratio irrigation » water irrigation, basin irrigation, national irrigation
support group » support from, support grant

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: (( (export OR exports) ratio irrigation schemes. ) or ( support group integration volume. ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( (export OR exports) ratio irrigation schemes. ) OR ( support group integration volume. )).
• The words AND, OR and NOT may confuse the search; try adding quotes: "(( (export OR exports) ratio irrigation schemes. ) or ( support group integration volume. ))".
• Adding a wildcard symbol may retrieve word variants: (( (export OR exports) ratio irrigation schemes. ) or ( support group integration volume. ))*.