Yesterday I pulled up my purple hull peas, and planted okra seeds in their place. It was hard to make myself pull up the purple hulls because the plants were still alive and had some production, but I know that they were more or less spent.
I planted 2 rows of black eyed peas (California #5) and 2 rows of purple hulls (pinkeye), both seeds were from Burpees. I was amazed at the difference in production. The black eyed peas had more than 2x as many pods. I planted the same number of seeds, watered and fertilized the same. If they hadn't of been side by side I don't think I would have noticed how much better the black eyed peas did.
I pulled up 1 row of purple hulls, so in the picture you can see (left to right) 1 row of purple hulls, one empty row, and 2 rows of black eyed peas. The black eyed peas are still producing and the plants are twice as large. Go figure.