Perhaps you should try some spelling variations:
irrigation schemes » irrigation systems
irrigation scheme » irrigation systems
spate irrigation » scale irrigation, water irrigation, surge irrigation
grid irrigation » grain irrigation, drip irrigation, gray irrigation
support grid » support agri, support grant, support group
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 grid irrigation schemes. ) or ( supply spate irrigation scheme. ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( support grid irrigation schemes. ) OR ( supply spate irrigation scheme. ))*.