well your analysis of the amount of nutrients in the stover of 200 bu. corn is right,your assumption that they are removing it all is wrong.we have a plant local to us.so here is what they are doing.they are just removing what comes out the chaffer on the combine,so mostly cobs and shucks,and stalk that is removed is incidental and not really wanted,in fact two things happen with stalks,their fermentation process is set up with a certain stalk to cob ratio and if it goes outside certain parameters it messes up the fermentation,and if alot of stalk is coming in it means the baler is too close to the ground and is picking up dirt/mud, apparently very bad deal.right now they removing about 1ton/acre.