Perhaps you should try some spelling variations:
"support grid irrigation schemes." » "support grid irrigation scheme.", "support grid irrigation systems.", "support grain irrigation schemes.", "support gray irrigation schemes.", "support syria irrigation schemes.", "support agri irrigation schemes.", "support grant irrigation schemes.", "support group irrigation schemes."
"support drip irrigation schemes." » "support drip irrigation scheme.", "support drip irrigation systems.", "support deep irrigation schemes.", "support during irrigation schemes.", "support crops irrigation schemes."

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: (("support grid irrigation schemes.") OR ("support drip irrigation schemes."))~.
• Removing quotes may allow a broader search: (( support grid irrigation schemes. ) or ( support drip irrigation schemes. ))~.
• Adding a wildcard symbol may retrieve word variants: (("support grid irrigation schemes.") or ("support drip irrigation schemes."))*.