help fluff up a compost heap. Buckwheat hulls are popular as a mulch
because they adsorb moisture easily, look attractive, and stay in
place. Their C/N is high. Oat and rice hulls are similar products.

_Canola meal._ See: _Cottonseed meal._

_Castor pomace_ is pulp left after castor oil has been squeezed from
castor bean seeds. Like other oil seed residues it is very high in
nitrogen, rich in other plant nutrients, particularly phosphorus,
Castor pomace may be available in the deep South; it makes a fine
substitute for animal manure.

_Citrus wastes_ may be available to gardeners living near industrial
processors of orange, lemon, and grapefruit. In those regions, dried
citrus pulp may also be available in feed stores. Dried orange skins
contain about 3 percent phosphorus and 27 percent potassium. Lemons
are a little higher in phosphorus but lower in potassium. Fruit
culls would have a similar nutrient ratio on a dry weight basis, but
they are largely water. Large quantities of culls could be useful to
hydrate stubbornly dry materials like straw or sawdust.

Like other byproducts of industrial farming, citrus wastes may
contain significant amounts of pesticide residues. The composting
process will break down and eliminate most toxic organic residues,
especially if the pile gets really hot through and through. (See
also: _Leaves) _The effect of such high levels of potassium on the
nutritional qualities of my food would also concern me if the
compost I was making from these wastes were used for vegetable
gardening.