Perhaps you should try some spelling variations:
"crop management activity." » "crop management activities.", "crop management facility.", "crop management authority.", "case management activity.", "flood management activity."
"crisis management activity." » "crisis management activities.", "crisis management facility.", "crisis management authority."
"change management control." » "finance management control.", "waste management control."
"demand management contracts." » "land management contracts.", "debt management contracts."
"cash management water." » "cash management case.", "cash management based.", "cash management a.", "asset management water."
"risk management data." » "risk management a.", "risk management case."
"farm management concepts." » "bank management concepts.", "data management concepts.", "forest management concepts."

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: (((((("crop management activity.") OR ("crisis management activity."))) OR ((((("change management control.") OR ("chain management control."))) OR ((((("cash management water.") OR ("risk management data."))) OR ("demand management contracts."))))))) OR ("farm management concepts."))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((((((\"crop management activity.\") or (\"crisis management activity.\"))) or (((((\"change management control.\") OR (\"chain management control.\"))) or (((((\"cash management water.\") or (\"risk management data.\"))) or (\"demand management contracts.\"))))))) or (\"farm management concepts.\"))~".
• Removing quotes may allow a broader search: (((((( crop management activity. ) or ( crisis management activity. ))) or ((((( change management control. ) OR ( chain management control. ))) or ((((( cash management water. ) or ( risk management data. ))) or ( demand management contracts. ))))))) or ( farm management concepts. ))~.
• Adding a wildcard symbol may retrieve word variants: (((((("crop management activity.") or ("crisis management activity."))) or ((((("change management control.") OR ("chain management control."))) or ((((("cash management water.") or ("risk management data."))) or ("demand management contracts."))))))) or ("farm management concepts."))*.