Perhaps you should try some spelling variations:
irrigation schemes » irrigation scheme, irrigation systems
irrigation system » irrigation systems, irrigation water, irrigation scheme
grain irrigation » gray irrigation, gravity irrigation, drip irrigation
spate irrigation » scale irrigation, water irrigation, surge irrigation
support grain » support grant, support grid, support trainer
supply spate » supply system, supply side, supply water

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

• Performing a fuzzy search may retrieve terms with similar spellings: (( support grain irrigation schemes. ) or ( supply spate irrigation system. ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( support grain irrigation schemes. ) OR ( supply spate irrigation system. )).
• Adding a wildcard symbol may retrieve word variants: (( support grain irrigation schemes. ) or ( supply spate irrigation system. ))*.