Although the serfdom of state-owned workers had been abolished long before, the abolition itself was not a momentous revolutionary action. 

The state-owned serfs were gradually introduced into their new status, partially by [a system of graduate payments][1] to the government and partially by a system of state-employment commissions.

Since the status of state-owned serfs was not abolished at once, their emancipation was happening step by step (and [not at equal pace everywhere along the Russian Empire][2]). 

Hence, the term refers to the same thing as before: state-owned serfs. 

**UPD:** It has just come up to my mind that the term could refer to a former status of the serfs - that is, 'a serf who originates from the state-owned class'; 'a descendent from the class', provided that there was no new name for the emancipated serfs. The meaning of the Genitive case in this phrase could be similar to that oif [Exessive][3] in Votian, Finnish and Estonian. The ultimate solution should be based upon the context of the Imperial Decree, I guess.


  [1]: https://ru.wikipedia.org/wiki/%D0%93%D0%BE%D1%81%D1%83%D0%B4%D0%B0%D1%80%D1%81%D1%82%D0%B2%D0%B5%D0%BD%D0%BD%D1%8B%D0%B5_%D0%BA%D1%80%D0%B5%D1%81%D1%82%D1%8C%D1%8F%D0%BD%D0%B5
  [2]: http://elib.shpl.ru/ru/nodes/22431-kavelin-s-p-istoricheskiy-ocherk-pozemelnogo-ustroystva-gosudarstvennyh-krestyan-m-1912-trudy-obschestva-mezhevyh-inzhenerov-vyp-2#page/55/mode/inspect/zoom/4
  [3]: https://en.wikipedia.org/wiki/Exessive_case