Synthetic Substances in Crop Production

Allowed & prohibited substances, methods & ingredients 

There are two main criteria that determine whether a given substance, such as a fertilizer or pesticide, is allowed in organic crop production: 1. Synthetic substances are prohibited unless specifically allowed on the National List. 2. Nonsynthetic (natural) substances are allowed unless specifically prohibited on the National List. In addition to these guidelines, genetically modified organisms are prohibited because they are produced by a prohibited method. Sewage sludge is prohibited because it usually contains prohibited substances.

Synthetic substances allowed for use in organic crop production

The National List of synthetic substances includes materials that are specifically allowed in organic crop production. The list includes algaecides, disinfectants, sanitizers, irrigation system cleaners, herbicides, animal repellents, insecticides, miticides, pheromones, rodenticides, slug baits, plant disease controls, soil amendments, and plant growth regulators; in short, many of the materials needed for crop production. Any synthetic substance that is not on the National List is not allowed. For example, herbicides containing the synthetic material glyphosate are prohibited. Herbicides containing only natural substances, such as vinegar and clove oils, are allowed.

Non-synthetic substances prohibited for use in organic crop production

This is the National List of natural, or nonsynthetic, materials that are specifically prohibited in organic crop production. This list includes natural—but highly toxic—materials, such as arsenic.

Detailed Standards, Factsheets & Other Resources