Perhaps you should try some spelling variations:
irrigation schemes » irrigation scheme, irrigation systems
furrow irrigation » farm irrigation, crop irrigation, flood irrigation
irrigation system » irrigation systems, irrigation water, irrigation scheme
how irrigation » crop irrigation, from irrigation, high irrigation
supply how » supply shock

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 how irrigation schemes. ) OR ( supply furrow irrigation system. ))~.
• Adding a wildcard symbol may retrieve word variants: (( supply how irrigation schemes. ) or ( supply furrow irrigation system. ))*.