It is a slow-release, balanced material. In addition, alfalfa contains triacontanol, a root-growth stimulant, which I'm told earthworms love. Earthworms are a valuable tool in the garden as they aerate and fertilize the soil. Rosarians like to use alfalfa pellets. Blood meal is a quick source of nitrogen.
Bone meal has nitrogen and is a quick phosphorus source.
Bone meal also slightly increases soil pH, making it more alkaline. Cottonseed meal, too, is a good and rapid nitrogen source. I like fish emulsion, another nitrogen source that is about 5 percent sulfur. Fish meal is another nitrogen source. Seeds generally are collected in late summer or fall, when the pods begin to dry.