Tea leaves contribute similarly, and can be easily disposed of by composting the filter bag at the same time. Crushed eggshells are mostly calcium. Banana and citrus peels are a source of nitrogen, phosphorus and potassium. Do not use grease, as it will delay degradation of other materials by its coating action. Bones and meat scraps should be avoided because of their slow decomposition and risk of luring animals.
Manure can contribute a variety of nutrients and bacteria.
If straw or sawdust is used as animal bedding, nearly all of the nutrients are preserved that were not used by the animal. Farms and riding stables are usually glad to furnish individuals with all the manure needed for a home composting operation. Thin layers of soil or previously made compost can innoculate a heap with the necessary organisms to start the decomposition of new materials. Soil can also prevent the loss of nitrogen in the form of ammonia, and provide moisture and heat insulation if the pile is covered with a one to two inch layer. Wood ash is a source of potassium and can help to neutralize mixtures containing a large quantity of acidic materials such as oak leaves.