Permitted Chemicals List for Organic Farming

Vilma Ruddock
Contributor: Beth Asaff
organic farming

Despite the marketing appeal to consumers, produce labeled organic are not always exposed only to all-natural substances. To cover the essential elements of successful, productive farming, the United States Department of Agriculture (USDA), through their National Organic Program (NOP), maintains a list of synthetic chemicals they permit farmers to use for organic agriculture.

Top 10 USDA Organic Farming Chemicals

According to the NOP's evaluation criteria, a synthetic chemical is considered for use when "it cannot be produced from a natural source and there are no organic substitutes," and the substance is essential for handling organic products (see Subpart G, section 205.600, items (b)(2) and (b)(6 ) of the U. S. Electronic Code of Federal Regulations list). In addition, to be approved, a chemical should have no known adverse effects on the environment or consumer health.

The National Organic Standards Board (NOSB) recommends to the NOP what should be added or deleted on the national list of chemicals approved for organic farming. The following list of ten synthetic substances (listed in the Electronic Code of Federal Regulations, Subpart G, section 205.601) are available to organic farmers for essentials such as pest control, disinfection, control of weeds and other overgrowth, and to maintain soil quality when there are no organic alternatives.

1. Alcohols

Ethanol and isopropanol alcohols are permitted for use:

  • As a disinfectant and a sanitizer
  • To control the growth of algae
  • In farm irrigation system cleaning systems

2. Chlorine Compounds

Chlorine compounds kills bacteria, viruses, mold and algae. The NOP allows calcium hypochlorite, sodium hypochlorite, and chlorine dioxide to be used:

  • As disinfectants on pre-harvest crops
  • In soil irrigation system cleaning systems

Chlorine compounds must only be used in quantities that limit the amount of residual chlorine in the water that goes on the plants, or in water in the irrigation system that goes in the soil.

3. Copper Sulfate

Organic farmers can use copper sulfate to:

  • Suppress algae growth in aquatic rice farming
  • Control tadpole shrimp in aquatic rice farming
  • Get rid of insects, bacteria, fungi, plants, slugs

An organic farmer is not allowed to apply it more than once every 24 months, and in an amount that does not increase the baseline copper level in the soil above an approved level in an agreed-on time period.

4. Peracetic Acid

Peracetic acid is used:

  • To disinfect farm machinery
  • To disinfect planting material for seeds and starter plants
  • To control fungal or bacterial blight
  • Post-harvest food processing

It is also allowed in hydrogen peroxide products used as a disinfectant and for pest control.

5. Soap-based Herbicides

Soap-based herbicides are used as insecticdes and to control herb barriers and weed growth around:

  • Farm ornamental crops
  • Roadways, ditches, and right of ways
  • Building perimeters

6. Ammonium Carbonate

Ammonium carbonate is used to bait traps to catch flies and other insects. The chemical cannot be allowed to come into contact with crops or soil.

7. Boric Acid

Boric acid can be used for pest control in buildings. It is also used in liquid fertlizers as a source for the element boron to encourage healthy plant growth.

8. Sodium Carbonate Peroxyhydrate

In organic farming, sodium carbonate peroxyhydrate is used as a disinfectant, sanitizer, for cleaning irrigation systems, and as a fungicide and an algicide.

9. Sulfur Substances

Sulfur substances such as elemental sulfur and lime sulfur are allowed:

  • As insecticides and pesticides
  • To control plant disease
  • To repair (fertilize) a soil that is deficient in sulfur (elemental sulfur)

Sulfur dioxide may also be used, but only as a smoke bomb to control underground rodents.

10. Magnesium Sulfate

Magnesium sulfate, or Epsom salts, is allowed as a supplement to correct a soil deficient in magnesium. Before using this compound the soil has to be tested to prove the deficiency.

Other Chemicals Permitted in Organic Farming

The USDA National Organic Program also lists several other approved synthetic substances and supplements for use in organic farming:

  • Vitamin D3: For rodent control
  • Vitamins B1, C1, and E: To correct soil deficiencies in the nutrients
  • Sulfates: To correct soil deficiency in sulfates
  • Humic acids: Extracts of natural deposits are used to correct soil deficiencies
  • Other micronutrients: Such as boron, cobalt, copper, iron, magnesium, manganese, selenium zinc, to amend soil based on test results
  • Other copper compounds: Such as copper oxide, copper hydroxide and copper oxychloride can be used to control plant disease as long as copper accumulation in the soil is minimal
  • Liquid fish products: To amend soil nutrient deficiencies
  • Hydrated lime: To control plant disease
  • Potassium bicarbonate: For plant disease control
  • Oils: For plant disease control
  • Hydrogen peroxide: As an algicide and disinfectant
  • Ozone gas: To use in irrigation systems cleaning systems
  • Lignin sulfonate: As a floating agent used in post-harvest processing; also used to control dust and as a chelating agent
  • Ethylene gas: For regulation of pineapple flowering
  • Sodium silicate: For tree fruit and fiber processing post-harvest production
  • Pheromones: To manage insect populations

Know Your Organic Food Source

Organic farmers have a list of USDA permitted synthetic chemicals to choose from. It is impossible for you to know which of these a farmer uses to to optimize his food production or how he follows the USDA regulations. If you are concerned about what's in your organic vegetables and other produce, buy from local farmers you trust, or reputable stores that make an effort to source their organic products with care.

Permitted Chemicals List for Organic Farming