Perhaps you should try some spelling variations:
"supply surface irrigation system." » "supply scale irrigation system.", "supply surface irrigation water.", "supply surface irrigation scheme.", "supply service irrigation system.", "upper surface irrigation system."
"support deep irrigation systems." » "support deep irrigation waters.", "support deep irrigation schemes.", "support drip irrigation systems.", "support delta irrigation systems.", "support level irrigation systems.", "supported deep irrigation systems.", "support de irrigation systems.", "support does irrigation systems."

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

• Performing a fuzzy search may retrieve terms with similar spellings: (("support deep irrigation systems.") OR ("supply surface irrigation system."))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((\"support deep irrigation systems.\") OR (\"supply surface irrigation system.\"))*".
• Removing quotes may allow a broader search: (( support deep irrigation systems. ) OR ( supply surface irrigation system. ))*.