rubberTurtleFarm 1.3.1

local t = turtle

local function forward(x)
    for i = 1, x do
        t.forward()
    end
end

local function rTurn(x)
    for i = 1, x do
        t.turnRight()
    end
end

local function lTurn(x)
    for i = 1, x do
        t.turnLeft()
    end
end

local function up(x)
    for i = 1, x do
        t.up()
    end
end

local function down(x)
    for i = 1, x do
        t.down()
    end
end

local function back(x)
    for i = 1, x do
        t.back()
    end
end

local function gotoStart()
    rs.setAnalogOutput("left", 0)
    os.sleep(1)
    up(2)
    back(1)
    lTurn(1)
    forward(1)
end

local function rowUp()
    for i = 1, 4, 1 do
        t.dig()
        up(1)
    end
end

local function rowDown()
    for i = 1, 4, 1 do
        t.dig()
        down(1)
    end
end

local facing = t.detect()

local height = t.detect(down)

local function harvest(x)
    for i = 1, x do
        rTurn(1)
            if facing == true then
                if height == true then
                    rowUp()
                else
                    rowDown()
                end
            else
                if height == true then
                    forward(1)
                    lTurn(1)
                    rowUp()
                else
                    forward(1)
                    lTurn(1)
                    rowDown()
                end
            end
    end
end

local function gotoHome()
    back(2)
    lTurn(1)
    forward(1)
    down(5)
    os.sleep(1)
    rs.setAnalogOutput("left", 15)
    os.sleep(3600)
end

while true do
    gotoStart()
    rowUp()
    harvest(6)
    gotoHome()
end