Rails: how to submit multiple forms to the same table

I am currently building a tool for work. It involves submitting multiple job start and end times every day. There are several jobs and each one has a new run time every day. So to speed up the process I want to submit all of the run times in one form. Currently I have all of the forms appearing but when I submit only one submission goes through. What am I missing?

runtime.rb

class Runtime < ApplicationRecord
  belongs_to :Mrpjob
  accepts_nested_attributes_for :Mrpjob
end

runtimes_controller.rb

class RuntimesController < ApplicationController
  before_action :set_runtime, only: [:show, :edit, :update, :destroy]

  # GET /runtimes
  # GET /runtimes.json
  def index
    @runtimes = Runtime.all
    @sorting = @runtimes.order("date asc")
  end

  # GET /runtimes/1
  # GET /runtimes/1.json
  def show
  end

  # GET /runtimes/new
  def new
    @runtime = Runtime.new
    @mrpjobs = Mrpjob.all
    @runtimes = Array.new(Mrpjob.count)
  end

  # GET /runtimes/1/edit
  def edit
    @mrpjobs = Mrpjob.all
  end

  # POST /runtimes
  # POST /runtimes.json
  def create
    @runtime = Runtime.new(runtime_params)


    respond_to do |format|
      if @runtime.save
        format.html { redirect_to @runtime, notice: 'Runtime was successfully created.' }
        format.json { render :show, status: :created, location: @runtime }
      else
        format.html { render :new }
        format.json { render json: @runtime.errors, status: :unprocessable_entity }
      end
    end
  end

  # PATCH/PUT /runtimes/1
  # PATCH/PUT /runtimes/1.json
  def update
    respond_to do |format|
      if @runtime.update(runtime_params)
        format.html { redirect_to @runtime, notice: 'Runtime was successfully updated.' }
        format.json { render :show, status: :ok, location: @runtime }
      else
        format.html { render :edit }
        format.json { render json: @runtime.errors, status: :unprocessable_entity }
      end
    end
  end

  # DELETE /runtimes/1
  # DELETE /runtimes/1.json
  def destroy
    @runtime.destroy
    respond_to do |format|
      format.html { redirect_to runtimes_url, notice: 'Runtime was successfully destroyed.' }
      format.json { head :no_content }
    end
  end

  private
    # Use callbacks to share common setup or constraints between actions.
    def set_runtime
      @runtime = Runtime.find(params[:id])
    end

    # Never trust parameters from the scary internet, only allow the white list through.
    def runtime_params
      params.require(:runtime).permit(:start_time, :end_time, :date, :Mrpjob_id)
    end
end

_form.html.erb

<%= form_for @runtime, :html => { :class => "form-horizontal runtime" } do |f| %>

  <% if @runtime.errors.any? %>
    <div id="error_expl" class="panel panel-danger">
      <div class="panel-heading">
        <h3 class="panel-title"><%= pluralize(@runtime.errors.count, "error") %> prohibited this runtime from being saved:</h3>
      </div>
      <div class="panel-body">
        <ul>
        <% @runtime.errors.full_messages.each do |msg| %>
          <li><%= msg %></li>
        <% end %>
        </ul>
      </div>
    </div>
  <% end %>
  <div class="col-sm-6 padding">

    <div class="form-group">
      <%= f.label :start_time, :class => 'control-label col-lg-2' %>
      <div class="col-lg-6">
        <%= f.text_field :start_time, :class => 'form-control' %>
      </div>
      <%=f.error_span(:start_time) %>
    </div>
    <div class="form-group">
      <%= f.label :end_time, :class => 'control-label col-lg-2' %>
      <div class="col-lg-6">
        <%= f.text_field :end_time, :class => 'form-control' %>
      </div>
      <%=f.error_span(:end_time) %>
    </div>
    <div class="form-group">
      <%= f.label :date, :class => 'control-label col-lg-2' %>
      <div class="col-lg-6">
        <%= f.text_field :date, :class => 'form-control' %>
      </div>
      <%=f.error_span(:date) %>
    </div>

     <div class="row">
        <% @mrpjobs.each do |p| %>
          <div class="col-sm-2 text-center">
            <%= f.radio_button :Mrpjob_id, p.id %>
            <%= f.label :Mrpjob_id, p.name %>
          </div>
        <% end %>
    </div>

    <div class="form-group">
      <div class="col-lg-offset-2 col-lg-10">
        <%= f.submit nil, :class => 'btn btn-primary' %>
        <%= link_to t('.cancel', :default => t("helpers.links.cancel")),
                  runtimes_path, :class => 'btn btn-default' %>
      </div>
    </div>
  </div>

<% end %>

new.html.erb

<%- model_class = Runtime -%>
  <div class="page-header">
    <h1><%=t '.title', :default => [:'helpers.titles.new', 'New %{model}'], :model => model_class.model_name.human.titleize %></h1>
  </div>

  <div class="container">
    <div class="row">

        <% @runtimes.each do |runtime| %>
            <%= fields_for @runtime do |r| %>
              <%= render "form" %>
            <% end %>
        <% end %>
    </div>
  </div>