Perhaps you should try some spelling variations:
irrigation schemes » irrigation scheme, irrigation systems
system irrigation » systems irrigation, spate irrigation, system mitigation
supply system » supply systems
cost internet » post internet, loss internet, das internet
supply cost » supply costs
service. » services.

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

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