The speaker is never more elusive than when discussing his own erotic experiences.
His crisis with touch continues, and he has mixed feelings about this sense, which he calls both "loving" and "sharptoothed." Touch seems to exist inside him or beneath him, and it causes his to feel a physical pain and discomfort, coupled with intense pleasure.
The touch has "left him" with an "ache," which certainly sounds like ejaculation even if Whitman doesn't tell us so.
Having just seemingly described an act of "fertilization," he now describes the rain and growth of "sprouts." His own sexuality becomes part of a larger narrative about growth and life.