Agree, alfalfa is probably a champion nitrogen sink.

It is true in most climate, soil combinations alfalfa will produce double the amount of nitrogen that it utilizes.

Your unique combined altitude and latitude factors may be a factor in CP levels. Then again in those high production California desert climates, they claim adding nitrogen pays when production levels are over 10 tons/a per year.

I have little hope of equaling the Western Irrigated Quality, though that does not mean I will stop trying. Still, for bermudagrass hay, the rule of University is realize a better than 12% CP level, a harvest interval of 28 days or less is required. Well I was running 40 days between first and second cutting of bermudagrass hay days between cuttings and averaging in the 14% CP range. Much better than the local market will pay for. Went to a 47 day interval and had a 12.5% CP hay test. The key is years of 400 lbs, or more, of anhydrous ammonia. As you say it requires nitrogen to make protein.

I may change my mind at dome future date, but now I try to limit nitrogen to less than 40 lbs/A prior to planting.

Reno? December?