Planning and preparing rows for Vegetables.

I laid out my first row - that I will use to plant the vegetables.  This is the corral that is no longer being used as there are no animals on the farm.   The rows will be 50 feet long and 4 feet wide which is the width of the plastic mulch I will be using.   I will leave 3 feet between rows.   The third picture shows how wide the corral is and I estimate I will be have room for 13 rows that are 4 feet wide and 50 feet long.      I have to purchase a truck load of compost to till into the soil as the soil is hard and looks likes it has a lot of clay.