Perhaps you should try some spelling variations:
irrigation schemes » irrigation scheme, irrigation systems
trade irrigation » pradesh irrigation, scale irrigation, grain irrigation
aid conservation » land conservation, bird conservation, wild conservation
supply trade » supply case
supply aid » supply asia, supply a, supply ann

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: (( supply trade irrigation schemes. ) OR ( supply aid conservation efforts. ))~.
• Adding a wildcard symbol may retrieve word variants: (( supply trade irrigation schemes. ) or ( supply aid conservation efforts. ))*.