Perhaps you should try some spelling variations:
irrigation scheme » irrigation systems
drop irrigation » drip irrigation, crop irrigation, from irrigation
a integration » 3 integration, 2 integration, 4 integration
_ integration » _ integrated
supply drop » supply from, supply europe, supply crowd

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

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