Perhaps you should try some spelling variations:
irrigation schemes » irrigation scheme, irrigation systems
cost conservation » coastal conservation, forest conservation, joint conservation
trip irrigation » drip irrigation, crop irrigation, grain irrigation
supply cost » supply costs
supply trip » supply tariff, supply trade

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

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