The extracts or pulverized parts of several seas, including kelp, or algae are good sources of minerals, potassium, and sometimes nitrogen. Follow application directions carefully when spraying on leaves, because sea plants can affect plant growth when sprayed directly on leaves. For the best price, look for it at animal feed-supply stores. Animal processing by-products. 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.