Tilling Garden Rows

I have 5 rows with 3-4 inches of compost spread over them.  The rows are 50 feet long and 4 feet wide.   It took a lot of compost to cover all 5 rows, but compost is the best thing to improve your soil fertility.   I purchased a tiller and started tilling today.  I about broke my back because the soil was so dry and hard.  I did one full row and 1 pass through the second row.  I will water for a couple days to soak deep down into the soil then try again.   I want to mix the compost down as least 6-8 inches and the soil needs to be soft to till that deep.    Here are some pictures of the rows before tilling and then showing the row furthest to the left - completely tilled and one pass down the second row.