Perhaps you should try some spelling variations:
irrigation schemes » irrigation scheme, irrigation systems
integration theory » integration through, information theory, innovation theory
farm irrigation » scale irrigation, canal irrigation
supply farm » supply from, support farm
supply use » supply case, supply curve, supply asset
supply u.s » supply 1.3, supply 2.3, supply 3.3

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

• If you are trying to use Boolean operators, they must be ALL CAPS: (( supply farm irrigation schemes. ) OR ( ((supply use) OR (supply u.s)) integration theory. ))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "(( supply farm irrigation schemes. ) or ( ((supply use) OR (supply u.s)) integration theory. ))~".
• Adding a wildcard symbol may retrieve word variants: (( supply farm irrigation schemes. ) or ( ((supply use) OR (supply u.s)) integration theory. ))*.