function Coal()
  if turtle.getFuelLevel() < 40 and turtle.getItemCount(1) <2 then
    print "Bitte Treibstoff in den 1. Slot geben"
  end
end

function Refuel()
  if turtle.getFuelLevel() < 100 then
    turtle.select(1)
    turtle.refuel(turtle.getItemCount()-1)
  end
end

x=0
y=0

function Mv()
    Coal()
    Refuel()
    while not turtle.forward() do
        turtle.attack()
    end
end

function Startup()
    while turtle.forward() do
        x=x+1
    end
    turtle.turnRight()
    while turtle.forward() do
        y=y+1
    end
    turtle.turnRight()
    for l=1, x, 1 do
        Mv()
    end
    turtle.turnRight()
    for m=1, y, 1 do
        Mv()
    end
    turtle.turnRight()
end

function CheckBelow()
    success, data = turtle.inspectDown()
    if data.metadata == 7 then
        turtle.digDown()
        if data.name == "minecraft:carrots" then
            turtle.select(3)
            turtle.placeDown()
        elseif data.name == "minecraft:potatoes" then
            turtle.select(2)
            turtle.placeDown()
        end
    end
end

function CheckField()
    for j=1, y, 1 do
        for k=1, x, 1 do
            CheckBelow()
            Mv()
        end
        CheckBelow()
        if j%2 == 1 then
            turtle.turnRight()
            Mv()
            turtle.turnRight()
        elseif not j==y then
            turtle.turnLeft()
            Mv()
            turtle.turnLeft()
        end
    end
    if y%2 == 0 then
        TurnAround()
        for k=0, x, 1 do
            Mv()
        end
    end
    turtle.turnRight()
    for j=0, y+1, 1 do
        Mv()
    end
    turtle.turnRight()
end

function TurnAround()
    turtle.turnLeft()
    turtle.turnLeft()
end

function Chest()
    TurnAround()
    for n=5, 16, 1 do
        turtle.select(n)
        turtle.drop()
    end
    TurnAround()
end

Startup()
while true do
    CheckField()
    Chest()
    os.sleep(900)
end