Organic soil amendments are materials derived from plant and animal parts or residues such as Blood Meal, Compost, Bat Guano, Manure, Seaweed, and Worm Castings. Synthetic fertilizers are inorganic compounds – usually derived from by-products of the petroleum industry. Even petroleum has distant roots in living organic material (carbon from ancient plants and animals) but it doesn’t have other essential soil features.Plants cannot distinguish between organic or synthetic fertilizer – the nutrients are processed in exactly the same way. However, the similarity stops there. Chemical fertilizers add nutrients to the soil, but they don’t add anything else. Plants need more than just nutrients to survive. They need organic matter and living organisms. Synthetic fertilizers do not support microbiological life in the soil. The application of a synthetic fertilizer actually kills a significant percentage of beneficial microorganisms. These tiny creatures are responsible for breaking down organic matter into a stable amendment for improving soil quality and fertility. Some convert nitrogen from the air into a plant useable form. Compost and organic matter introduce beneficial microorganisms into the soils complex mix. Composts contain an astonishing variety of microbes, many of which may be beneficial in controlling pathogens. Beneficial microbes help to control plant pathogens. Organic matter improves soil structure, resulting in a crumb like structure that improves water retention, and air infiltration and enhances soil fertility. Plants require 13 nutrients. There are three primary macronutrients: nitrogen (N), phosphorus (P), and potassium (K). These nutrients are used in significant amounts, so they must be replaced periodically to sustain productivity. The secondary nutrients are: calcium Ca), magnesium (Mg), and sulfur (S). There are usually enough of these nutrients in the soil, so additional fertilization is not always needed. The micronutrients used in small quantities are: boron (B), copper (Cu), iron (Fe), chloride (CI), manganese (Mn), molybdenum (Mo), and zinc (Zn). Organic amendments (which include more than nutrients) can be highly variable in composition.