productive vs productiveness

productive is not a noun while productiveness is a noun.

Word	Noun	Adjective	Verb	Adverb
productive	No	Yes	No	No
productiveness	Yes	No	No	No

productive (noun)	productiveness (noun)
	the quality of being productive or having the power to produce

productive (adjective)	productiveness (adjective)
producing or capable of producing (especially abundantly)
having the ability to produce or originate
marked by great fruitfulness
yielding positive results