Different organizations have tried various Knowledge Capture incentives, including making content submission manditory and incorporating rewards into performance measurement plans. More successful approaches typically include incorporating knowledge capture into exiting business processes.
For example, when a consulting engagement ends, a Standard Operating Process for the firm is for the consultant to submit the proposal that won the business for that engagement or altenratively, write up a post-mortem of the engagement with lessons learned.
Similarly, in investment banking, at the end of a new deal, the bank analyst could have a standard procedure to submit the appropriate deal documents that represent the unique strategies or learnings that made the particular deal a success.