Alfalfa is an organic source of nitrogen which supports the plant in making new growth, specifically leaves and stems. As an organic source it is released into the ground slowly and it supports healthy soil organisms. At least that's the standard theory. Here's an alternative one.
http://rodaleinstitute.org/mes... . Why it works may be a topic of heated discussion by some; but evidently it does work. You can buy it as pellets. It's also a component of Mills Magic.
