Fish fertilizers are considered organic. Many do not meet the National Organic Program standards but are sold as organic. “Organic fertilizer refers to a soil amendment derived from natural sources that guarantees, at least, the minimum percentages of nitrogen, phosphate, and potash,” states Colorado State University’s report on organic fertilizers. Fertilizers such as fish products require a minimum soil temperature of 50 degrees Fahrenheit along with moisture to be effective. Fish fertilizer comes in various forms.
Fish emulsion fertilizer was one of the first organic fertilizers marketed. It is usually made from the menhaden fish, which is not considered edible. Menhaden are caught in harbors and by drivers along the coastline where waters can be polluted.The fish meal is removed and sold as pet food, the remaining oil used in fish oils and the rest heat processed as emulsion. The heat processing may destroy necessary nutrients, unfortunately. Another drawback is that the emulsion is thick, difficult to use in a sprayer and has a strong odor.
Fish Bone Meal
Pulverized fish bones make up fish bone meal, a good source of organic phosphorus and calcium. Plants need phosphorus, nitrogen and potassium in large amounts. As a single ingredient fertilizer it is used on all types of vegetables and flowers and is especially beneficial for roots, buds and blooms. Fish bone meal also contains many trace elements, called micronutrients.
Fish meal fertilizer is ground and heat dried fish waste. The heat processing deteriorates some of its protein, enzyme and nutrient content, but it is still very high in nitrogen. It has more nutrients than fish emulsions do, according to Colorado State University’s report. It has a release time of one to four months, which means it provides slow release of nutrients that are taken up into the plant as needed.
Fish powder is heat dried and turned into a water soluble powder. It is very high in nitrogen, with a typical N-K-P analysis of 12-.025-1. It is sometimes mixed into a solution and injected into an irrigation system. It also adds micronutrients to the soil.