2-row generally has the lowest nitrogen content, therefore has more
convertable starch - that means more fermentable sugars and higher
6-row has more husks on each seed and therefore contains much more of
the enzymes required to convert all the starches in a mash.
Usually, if you are mashing corn or other non-malted grains, you want
to add some 6-row for the enzymes. If you are mashing all barley
(like I am at the moment) You want to use mostly 2-row for maximun
yeild, but also add some 6-row to ensure you have plenty of enzymes
for the conversion.