Recommendations for the commercial growers is a balanced fertilizer at planting, depending on soil tests, and a shot of nitrogen midway through the season.
I use compost, add a tablespoon of 6.5-6-26 mixed in before planting, water the transplants in with 15-30-15 liquid, and feed the plants a cupful of 250 ppm nitrogen every 3 - 4 days starting a couple of weeks after planting (once the plants get their feet under them!), shutting off mid July to let them use up the N so it doesn't affect taste.
Takes about 20 minutes per feeding for a hundred plants. It's a good chance to check each plant for possible problems, and suckers.
I use a 200 ml tuna fish can dipper screwed onto a 3 ft broomstick handle, and pour the solution around the base of each plant, onto the ground rather than the leaves to avoid possible burn. My weed barrier is shaped to form a 12 - 15" bowl around each plant to funnel the liquid into the base of the plant rather than running off to the sides, and I pinch off most of the bottom leaves to give me a clear shot at the base of the plant. They don't amount to anything anyway, and a friend dries them and uses them in his bee smoker.
Haven't done a control without the "spoon feeding", but it seems to work ok, and makes me feel good too!
I tried different feeding rates on one variety last year (one scoop, 2 scoops, 3 scoops per feed on each of 10 plants) but saw no visual difference. And the leaf is still aging in storage, so haven't got finished weights from the different trials yet.