Perhaps you should try some spelling variations:
irrigation requirements » irrigation equipment, nutrition requirements
requirements depth » requirements derchi, requirements data, requirements defects
depth decision » death decisions, health decision, depth design
david parker » david payne, david parra, david pearce
david wave » david wake, david weaver, david waite
david cake » david wake, david clarke, david casey

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: irrigation requirements depth decision ((david wave) OR (((david cake) OR (david parker))))~.
• Adding a wildcard symbol may retrieve word variants: irrigation requirements depth decision ((david wave) or (((david cake) or (david parker))))*.