After an order determining the amount of bonds which should be issued, the board shall call a bond election to submit to the voters a proposal of whether or not bonds in the amount determined in the order should be authorized when either:

1. (a) The board so determines.

2. (b) The board receives a petition requesting the election signed by either:

   1. (1) A majority in number of the holders of title to land who are also the holders of title to a majority in value of all of the land.
   2. (2) Five hundred or more persons, each of whom is either an elector or a holder of title to land and which petitioners include the holders of title to not less than 20 per cent in value of all of the land.