Perhaps you should try some spelling variations:
irrigation development » education development
practitioners system » practitioners chapter, practitioners website, practitioners guide
practitioner survey » practitioner guide, practitioners course
cfa irrigation » alfa irrigation, canal irrigation, farm irrigation

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

• Performing a fuzzy search may retrieve terms with similar spellings: cfa irrigation development ((practitioners system) or (practitioner survey))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: cfa irrigation development ((practitioners system) OR (practitioner survey)).
• Adding a wildcard symbol may retrieve word variants: cfa irrigation development ((practitioners system) or (practitioner survey))*.