What is in organic fertilizer?

Animal and vegetable matter are what is in organic fertilizer. Organic fertilizer therefore may include algae, green manure (decomposing crop leftovers), and seaweed as well as animal matter (bones, hides, hooves, horns, litter, powdered blood, skins, manure), guano, manure, and slurry. It also may involve mineral matter since peat improves aeration and moisture retention.