hey, why not just chuck ya plant a steak? medium rare?
I'd use soy protein, though. General Organics and Roots Organics all use Soy. Whey is a nasty product, especially if you're concerned about animal welfare/consequences of industrial animal farming. More expensive than soy, too.
Like fung said, only for use in organics, unless you want to have massive bacto blooms.
If your looking for amino acids, the plant takes up Ammonium ions in the roots. Ammonia (after it has the plant has up-taked it) is assimilated into amino acids (glutamine, asparagine) which can be further metabolized to
produce other N-containing compounds.
Nitrate will first be reduced to nitrite by nitrate reductase which uses NADPH as electron donor. Nitrite will
be further reduced to ammonia by nitrite reductase which uses reduced ferredoxin as electron donor.
The rest of the whey would go to the decomposers, fungi, and microbial life.