How to Convert to Organic Soil


Soil that has been farmed or gardened "conventionally," using chemical herbicides and pesticides, can usually be converted to organic standards over a period of years. How successful the process is depends on the types and quantities of chemicals used, the soil type and characteristics and the length of time allowed for the transition. Three years is considered to be the minimum period necessary.

Testing and Remediating

Step 1

Test the soil to find out what chemicals it contains. Your local County Cooperative Extension office can help you find a competent soil-testing laboratory and provide instructions on how to take soil samples.

Step 2

Take safety precautions if the results of the soil rest reveal hazardous chemicals. You may need to wear a face mask, or even a respirator, gloves and protective clothing when working with the soil. You should avoid breathing any dust, and you should carefully wash your hands and clothing after soil contact.

Step 3

Add at least 4 inches of good-quality compost over the entire area, and incorporate it into the top 6 inches of soil. For large areas this may amount to many tons of material, but compost is necessary as a first step in restoring the soil to a healthy condition. Chemicals destroy soil life, which negatively impacts soil structure. Compost helps to support soil life that is a necessary part of healthy, organic soil.

Step 4

Plant a beneficial cover crop in the spring or early summer, such as a combination of vetch (a legume) and buckwheat. Legumes have an extensive root structure and fix nitrogen in the soil, and buckwheat provides ample vegetative matter. At the end of the season, cut these crops down and incorporate them into the soil, adding organic matter. Follow these crops with a winter cover crop, such as rye, that protects the soil from erosion from wind and rain.

Step 5

Repeat the cover crop routine during years two and three. Take soil tests in the spring and fall to assess your progress in ridding the soil of chemical residues. Some agricultural and horticultural chemicals, such as arsenic, will linger in trace amounts for many years.

Tips and Warnings

  • Obtain the Material Safety Data Sheets (MSDS) on all the chemicals found in your soil. Carefully read and follow the warning statements.

Things You'll Need

  • Laboratory soil test
  • Personal protective equipment
  • Compost
  • Cover crop seeds
  • Seed-sowing equipment


  • U.S. Department of Agriculture: National Organic Program
  • U.S. Department of Agriculture: Laws and Regulations, Organic Certification

Who Can Help

  • Organic Materials Review Institute: Welcome
Keywords: farm chemicals, garden chemicals, soil testing, organic soil, certified organic

About this Author

Peter Garnham has been a garden writer since 1989. Garnham is a Master Gardener and a Contributing Editor for "Horticulture" magazine. He speaks at conferences on vegetable, herb, and fruit growing, soil science, grafting, propagation, seeds, and composting. Garnham runs a 42-acre community farm on Long Island, NY.