Green LeafConventionally manufactured fertilizers have some disadvantages. According to National Geographic, fertilizers are commonly derived from petroleum. In fact, a single 40-pound bag contains the equivalent of 2.5 gallons of gasoline. Excess fertilizers, not absorbed by plants, may run off into storm drains that feed into rivers and streams, contributing to algae blooms, depriving waterways of oxygen and killing aquatic life.

Also, according to National Geographic, natural fertilizers such as biobased fertilizers, may promote the growth of beneficial bacteria and fungi and attract earthworms to that build soil structure and foster healthy plants. National Geographic Website – Fertilizer Buying Guide Biobased fertilizers are often made from plant products such as soybean meal, cottonseed meal, and sea kelp and may provide a cost-efficient alternative to traditional fertilizers. The BioPreferred Catalog provides a number biobased fertilizers to consider, and biobased fertilizers are available in major retail stores.

From National Geographic website buyers guide.  NOFA is a certifing agency of the USDA certified organic program

“NOFA Approved” and “OMRI Listed”: The Organic Materials Review Institute (OMRI) and the Northeast Organic Farming Association (NOFA), an accredited certifying agency for the USDA National Organic Program, approve products that have been composted according to USDA Organic standards. The only synthetic materials that can be added to NOFA approved compost are those allowed in organic crop production.