Feldon, this link might be useful for you.
http://www.organicgardening.com/feat...16-183,00.html
Perhaps your production was down for OSP because your temps were above 75F. I know ours were and so all my peas finished at the same time last week despite different planting times. Were you growing the I or II version? It seems like they both produce about the same amount of snow peas, but the OSPII has more disease resistance. I have about a 3-1/2' long area where the peas are planted on both sides of a 3' trellis 2 inches apart (yes, you can even do 1 inch apart). I probably got more than 4 gallon bags full of snow peas from that one sowing. And no, I did not load it with fertilizer. I only fed it a general purpose home-made organic fertilizer about halfway through its' growing cycle.
I always have lower shell pea production, but they are a different beast
. I am willing to put up with lowered production because they are just so yummy!
Tiffanie