Tree Farm Creator

d = 9

function placeDirt()
    turtle.select(d)
    if turtle.getItemCount() > 0 then

    else
        if d == 16 then
            error()
        else
            d = d + 1
            turtle.select(d)
        end
    end
    turtle.placeDown()
    turtle.back()
end

function placeTree()
    turtle.select(5)
    if turtle.getItemCount() > 0 then
        turtle.place()
    else
        error()
    end
end



print("+-------------------------------------+")
print("| Auto Tree Farm Creator              |")
print("+-------------------------------------+")
print("| Slot 1: Fuel                        |")
print("| Slot 5: Saplings                    |")
print("| Slot 9-16: Dirt/Grass               |")
print("+-------------------------------------+")
print("| Place turtle facing away from       |")
print("| desired direction. Insert items.    |")
print("| Press enter to start.               |")
print("+-------------------------------------+")
print("")
read()
turtle.select(1)
turtle.refuel()
turtle.up()
while true do
    placeDirt()
    placeDirt()
    placeDirt()
    placeDirt()
    placeDirt()
    placeDirt()
    placeTree()
end