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

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 system."))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("support grid irrigation schemes.") OR ("supply spate irrigation system.")).
• Removing quotes may allow a broader search: (( support grid irrigation schemes. ) or ( supply spate irrigation system. )).
• Adding a wildcard symbol may retrieve word variants: (("support grid irrigation schemes.") or ("supply spate irrigation system."))*.