Perhaps you should try some spelling variations:
irrigation system » irrigation systems, irrigation water, irrigation scheme
crop irrigation » drip irrigation, scale irrigation, canal irrigation
supply trade » supply side
support crop » support crops, support group, support cross
supply case » supply cost, supply chain, 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 trade) or (supply case)) information theory. ) or ( support crop irrigation system. ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( ((supply trade) OR (supply case)) information theory. ) OR ( support crop irrigation system. )).
• Adding a wildcard symbol may retrieve word variants: (( ((supply trade) or (supply case)) information theory. ) or ( support crop irrigation system. ))*.