Pigeon pea, Cajanus cajan, has been cultivated for at least 3000 years, is a perennial (although seed yield drops considerably after the first 2 yrs.) legume of the semi-arid tropics and very drought resistant and heat tolerant. It enriches soil through symbiotic nitrogen fixation. Pigeon pea can be used as a Green manure, the nitrogen attached to the roots is released when the plant is cut back, however most of the fixed N is transferred to the seed after flowering. It tolerates poor soils better than some other green manures and ground covers. Seedlings emerge (under irrigation or after rain) 2-3 weeks after sowing, growth is slow until the taproot develops.
Once fully dried the seed will keep for several years. In India split pigeon pea is known as Toor dal or Toorvar. Pigeon peas contain high levels of protein (per 100 g – 21.7g in dried seed, 7.2g in fresh) and the important amino acids methionine, lysine, and tryptophan. In contrast to the mature seeds, the immature seeds are generally lower in nutritional values, however they contain a significant amount of vitamin C, and have a slightly higher fat content.
Pods will generally spring open once seed is mature in dry weather. To assist in gleaning, try rolling them underfoot in a woven bag to open the pods, you can winnow after they have been separated, or put them in a bowl of water and pick out anything that floats.
Seeds can be soaked overnight before cooking, or done quickly in a pressure cooker. Discard the cooking/soaking water. Personally I find they have a slight nutty flavour when cold after cooking, and hold their shape fairly well. It can be used in soups, curries, salads as an easily reachable alternative to lentils (i.e. they grow in the YSCG). Dried peas may be sprouted briefly to reduce indigestible sugars (hence less abdominal bloating), then cooked.
http://en.wikipedia.org/wiki/Pigeon_pea – 2 Nov 2014
http://www.tropicalforages.info/key/Forages/Media/Html/Cajanus_cajan.htm – 2 Nov 2014
http://www.fao.org/ag/agp/AGPC/doc/Gbase/data/pf000150.htm – 2 Nov 2014
** Thanks to Russell for this great information