_Hoof and horn meal._ Did you know that animals construct their
hooves and horns from compressed hair? The meal is similar in
nutrient composition to blood meal, leather dust, feather meal, or
meat meal (tankage). It is a powerful source of nitrogen with
significant amounts of phosphorus. Like other slaughterhouse
byproducts its high cost may make it impractical to use to adjust
the C/N of compost piles. Seed meals or chicken manure (chickens are
mainly fed seeds) have somewhat lower nitrogen contents than animal
byproducts but their price per pound of actual nutrition is more
reasonable. If hoof and horn meal is not dispersed through a pile it
may draw flies and putrefy. I would prefer to use expensive
slaughterhouse concentrates to blend into organic fertilizer mixes.

_Juicer pulp:_ See _Apple pomace._

_Kelp meals_ from several countries are available in feed and grain
stores and better garden centers, usually in 25 kg (55-pound) sacks
ranging in cost from $20 to $50. Considering this spendy price, I
consider using kelp meal more justifiable in complete organic
fertilizer mixes as a source of trace minerals than as a composting
supplement.

There is a great deal of garden lore about kelp meal's
growth-stimulating and stress-fortifying properties. Some
garden-store brands tout these qualities and charge a very high
price. The best prices are found at feed dealers where kelp meal is
considered a bulk commodity useful as an animal food supplement.

I've purchased kelp meal from Norway, Korea, and Canada. There are