Perhaps you should try some spelling variations:
irrigation systemss » irrigation systems, irrigation schemes, navigation systems
irrigation system » irrigation systems, irrigation water, irrigation scheme
rural irrigation » murray irrigation, canal irrigation, gray irrigation
case irrigation » scale irrigation, use irrigation, change irrigation
supply rural » supply curve
supply case » supply cost, supply chain, supply curve

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

• The words AND, OR and NOT may confuse the search; try adding quotes: "(( supply case irrigation system. ) OR ( supply rural irrigation systemss. ))~".
• Adding a wildcard symbol may retrieve word variants: (( supply case irrigation system. ) OR ( supply rural irrigation systemss. ))*.