Industries such as dairy farming and meat processing generate waste materials that are dried or minimally processed into fertilizers. Blood meal is a rich source of nitrogen that is quickly available, so use with care. Bonemeal is a rich source of phosphorus and calcium, and it supplies moderate amounts of nitrogen. Fish products can be fairly rich in nitrogen, phosphorus, and potassium, but read the labels because nutrient concentrations vary. Although making compost from a variety of raw materials is possible, the finished products are remarkably similar in their final concentrations of nitrogen, phosphorus, and potassium.
Composts are available commercially or can be homemade.
They can be used along with other fertilizers. Ingredients in commercial composts include various kinds of animal manures and lawn and garden wastes. The composition of various manures vary not only with the kind of animal source, but also with the age of the animal, the bedding, and method of manure storage and application. Cow manure is low in nutrients, but plants can absorb them moderately quickly. Manure from seabirds or bats are rich in nutrients, but not in organic matter.