Perhaps you should try some spelling variations:
furrow irrigation » farm irrigation, crop irrigation, flood irrigation
irrigation scheme » irrigation systems
male migration » female migration, die migration, climate migration
supply furrow » supply from
a migration » der migration

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

• Performing a fuzzy search may retrieve terms with similar spellings: (( supply ((male migration) OR (a migration)) process. ) or ( supply furrow irrigation scheme. ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( supply ((male migration) OR (a migration)) process. ) OR ( supply furrow irrigation scheme. )).
• The words AND, OR and NOT may confuse the search; try adding quotes: "(( supply ((male migration) OR (a migration)) process. ) or ( supply furrow irrigation scheme. ))".
• Adding a wildcard symbol may retrieve word variants: (( supply ((male migration) OR (a migration)) process. ) or ( supply furrow irrigation scheme. ))*.