Here at the Extension office, I have raised beds that contain mustard, turnips, and kale. Today I harvested about 7.5# of greens. Here's the breakdown:
Mustard -- 5.05#
Turnips -- 1.61#
Kale -- 0.88#
TOTAL = 7.54#
The picture to the right shows kale, turnip greens, and mustard greens, the entire first harvest from 67.5 sq ft of raised beds.
Mind you, this is only my first harvest. Mustard was by far the largest of the 3 crops, all planted on Aug 15, 2011. Kale is so lightweight compared to mustard, it may never rival it in the number of harvested pounds. But on a small scale, you don't exactly make decisions based on yield. You grow what you like to eat.
Each bed of greens measures 7.5 ft x 3 ft., only 22.5 sq ft of space.
You can grow a lot in a little bit of space, something that's been proven over and over. Now, gotta get to finding me some good recipes.