Perhaps you should try some spelling variations:
irrigation scheme » irrigation systems
crop irrigation » drip irrigation, scale irrigation, canal irrigation
eu integration » _ integration, deep integration, data integration
a integration » _ integration, can integration, data integration
supply crop » supply crowd, supply curve

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

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