Banana skins and stalks are soft and lack strong fiber. They are moderately rich in phosphorus, potassium, and nitrogen. Consequently they rot quickly. Like other kitchen garbage, banana waste should be put into the core of a compost pile to avoid attracting and breeding flies. See also: Garbage.
Basic slag is an industrial waste from smelting iron. Ore is refined by heating it with limestone and dolomite. The impurities combine with calcium and magnesium, rise to the surface of the molten metal, and are skimmed off. Basic slag contains quite a bit of calcium plus a variety of useful plant nutrients not usually found in limestone. Its exact composition varies greatly depending on the type of ore used.
Slag is pulverized and sold in sacks as a substitute for agricultural lime. The intense biological activity of a compost pile releases more of slag's other mineral content and converts its nutrients to organic substances that become rapidly available once the compost is incorporated into soil. Other forms of powdered mineralized rock can be similarly added to a compost pile to accelerate nutrient release.
Rodale Press, publisher of Organic Gardening magazine is located in Pennsylvania where steel mills abound. Having more experience with slag, Rodale advises the user to be alert to the fact that some contain little in the way of useful nutrients and/or may contain excessive amounts of sulfur. Large quantities of sulfur can acidify soil. Read the analysis on the label. Agriculturally useful slag has an average composition of 40 percent calcium and 5 percent magnesium. It must also be very finely ground to be effective. See also: Lime and Rock dust.
Beet wastes, like bagasse, are a residue of extracting sugar. They have commercial value as livestock feed and are sold as dry pulp in feed stores located near regions where sugar beets are grown. Their C/N is in the vicinity of 20:1 and they may contain high levels of potassium, reaching as much as 4 percent.
Brewery wastes. Both spent hops (dried flowers and leaves) and malt (sprouted barley and often other grains) are potent nutrient sources with low C/N ratios. Spent malt is especially potent because brewers extract all the starches and convert them to sugar, but consider the proteins as waste because proteins in the brew make it cloudy and opaque. Hops may be easier to get. Malt has uses as animal feed and may be contracted for by some local feedlot or farmer. These materials will be wet, heavy and frutily odoriferous (though not unpleasantly so) and you will want to incorporate them into your compost pile immediately.
Buckwheat hulls. Buckwheat is a grain grown in the northeastern United States and Canada. Adapted to poor, droughty soils, the crop is often grown as a green manure. The seeds are enclosed in a thin-walled, brown to black fibrous hulls that are removed at a groat mill. Buckwheat hulls are light, springy, and airy. They'll 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.
