OK I've sorted out the stems. The command \stemUp after the first dipped stem set all stems up. This takes them away from the lyrics which I prefer.

\version "2.18.2"
\header {
       encodingdate = "2018-06-19"
       title = "Marianina"
       subtitle = " "}
      
       voicedefault = \relative ees' {
          \key ees \major \time 4/4
         
               bes4. g8 c\stemUp c bes bes | aes4. f8 d4 r |\break
               c'4. aes8 d [d] c [c] | bes4. g8 ees4 r   |\break
               bes'4. g8 c [c] bes [bes] | aes4. f8 d4 r |\break
               c'4. aes8 d [d] c [c] | bes4 bes8 [bes] c [c] bes [bes]|\break
               aes4 aes8 [aes] bes [bes] aes [aes] | g2 ees'4. d8 |
                d c4. d c8 | c bes4. bes b8 | d4. c8 bes [bes] aes [f] | ees2 r2 |
       }
       \addlyrics {
       O'er the o -- cean flies a
       mer -- ry fay,
       Soft her wings are as a cloud of day'
       As she pass -- es all the blue waves say:
       Ma -- ria -- ni -- na do not Roam,
       Whith -- er, whith -- er is your home,
       Come and turn us in -- to foam,
       Ma -- ria -- ni -- na, Ma -- ria -- ni -- na, Come O come and turn us in -- to foam.
    }


\score{
      <<

          \context Staff="default"
          {
             \voicedefault
          }

      >>
          \layout {
          }
          \midi {}
}
\markup { \column{
    \line{ O' er the fields she passes to and fro, }
    \line{ By the cornstalks standing row by row, }
    \line{ Poppies whisper as they see her go }
    \line{ Marianina, little friend }
    \line{ Whither would your footsteps wend, }
    \line{ Come and teach us how to bend, }
    \line{ Marianina, Marianina, }
    \line{ Come, O come and teach us how to bend }
    \line{ [...] }
    }
}