Board Thread:Wiki Discussions/@comment-25134516-20140703093231/@comment-3568954-20140730095801

when Madara and the five kage were fighting after he found out she was a senju he said "You don't even have wood release" implying that Wood Release is a technique that other senju have had(likely all of them were Asura's successors but none the less it was still implied other senju have used it before) also the only reason Hashirama has Wood Release is because he has the chakra of Asura. so it is safe to assume that it is a power all of Asura's transmigrants have. and one of the reasons no normal person can use wood release is because the combination of earth and water creates very powerful life sustaining chakra that over takes the persons body and as such that is why hashirama could use it(because he is a transmigrant of Asura) so all Naruto would have to do is combine water and earth release he already has Earth Release so all he would need is water release