Ammonia = (NH3) is a gas containing 82% nitrogen.Used as a foliar feed in its aqueous form.
Cottonseed meal = A by-product resulting from the extraction of oil from cottonseed. Commercial cottonseed meal has nitrogen content of 6-7%. Generaly it is used as a partial source of nitrogen in mixed fertlizers. The nitrogen is readily available.
Blood meal = Blood meal is a by product of the meat-packing industry and has a nitrogen content of 12-14%. The nitrogen is available in a short time, but it does little for the mechanical properties of the soil.
Urea = Urea is a white crystaline compound cotaining 46% readily available nitrogen.
Fish emulsion = This is prepared from nonedible fish and waste from fisheries. It has about 8% nitrogen.
Bone meal = Two kinds, raw and steamed. Steamed bone meal has less nitrogen than raw, but more phosphoric acid. This material releases its nutrients slowly so can be used without fear of injuring the crop.
Rock phosphate = Mineral occuring in deposits throughout the world. Its effectiveness is dependant on its degree of fineness, and the reaction of the soil.
Superphosphate = A source of phosphoric acid in complete fertilizers and a direct treatment of soils deficient in phosphorous but well supplied with nitrogen and pottasium.
Slag = Finely ground by-product of steel manufacture. Its free lime content makes it of special value in the recalamation of acid soils.
Compost = Instead of throwing away organic waste, gather it together in an out of the way place and start a compost pile.
Greensand = Greensand contains slowly avaiable nutrients. Improvements are as much the result of soil condition as the nutrients.
Lime = An amendment to correct soil acidity, improve the properties of the soil, and promote bacterial activity.
Guano = The the composted or fossilized excrement of any roosting verebrate. Invertebrate excrement is called castings
Gypsum = Helps liberate pottasium and sulfur and conditions soil.
Feel free to help out on this one, I'm sure I forgot something....