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Alternative Soil Testing Laboratories

by Andy Pressman
NCAT Agriculture Specialist
June 2016

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How to Use This Database: For your convenience, you can search for suppliers by state, by product category, or by using a keyword. Before beginning your search, however, you are encouraged to read About This List.

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Soil Testing Laboratories Introduction:
Soil fertility management is essential for organic crop production. It is important for organic growers to understand the nutrient requirements of specific plants in order to grow, the value of applied nutrients, as well as the nutrient removal rate by crops during harvest. A soil test will help track the flow of nutrients in the soil so that adequate levels of nutrients can be applied in order to maintain optimum nutrient levels.

The accuracy of the soil test is dependent upon how well the soil is sampled. Most soil testing laboratories have specific recommendations on how to take and ship soil samples. Be sure to carefully read their instructions before you begin sampling. Here are a few general soil sampling guidelines:

  1. Collect 10 to 20 samples randomly from an area with similar soils and cropping history.
  2. Use a clean soil probe, auger, or spade to take each soil sample and place the composite of samples in a clean plastic container.
  3. Remove surface residue and collect samples from the top 6 to 8 inches or the depth of tillage.
  4. Soil samples should be mixed together, crushed, and air dried.
  5. Submit about one pint of the composite soil sample to the laboratory for testing. Laboratories often provide plastic bags for submitting soil samples. BE SURE TO IDENTIFY EACH SAMPLE.
  6. Repeat annually.

The link below is a video from Washington State University on taking soil samples.

About this Database
The aim of this database is to provide a range of soil testing labs and supplies that support the special analytical needs of farmers using organic or sustainable production methods. Fundamentally, these farmers are looking for more than just N-P-K-Lime fertilizer recommendations. ATTRA's Alternative Soil Testing Laboratories database can help you search for laboratories in your state, or search based on the information you are specifically looking for from your soil test (for example, organic nutrient recommendations, high tunnel soils, and compost).

Most land-grant universities offer free or low-cost soil testing services to farmers, gardeners, and landowners. The benefit of in-state analysis is that fertilizer recommendations are calibrated to soils in the region. These calibrations and associated fertilizer recommendations have been determined through decades of field trials at agricultural experiment stations. The standard soil test readily available through both land-grant university and commercial labs—provides data on soil nutrient levels (N, P, K, Ca, Mg) and a few soil chemical characteristics (pH and CEC). These parameters form the basis of fertilizer and liming recommendations. However, translating the results of a standard soil test into useful organic fertilizer recommendations is not a simple matter, especially for-scale producers. Most university soil testing labs don't provide practical fertilizer recommendations suited to commercial organic farming or small-scale sustainable production.

The Labs in This List Are Arganized in Two Broad Categories:
The first category focuses on tests for biological parameters and associated indicators such as soil organic matter and microbial activity. Farmers using organic production methods employ a range of biological farming practices to achieve a healthy, productive soil—e.g., crop rotations, cover crops and green manures, composts, minimally processed rock minerals, and in some instances, microbial inoculants. Accordingly, they need data that indicate soil biological health, not just mineral composition. They also need to understand how they can adjust agronomic practices to improve organic matter, soil tilth, microbial diversity, and nutrient mineralization and how this will affect their farm production.

The second category emphasizes mineral availability and mineral balances in the soil. The labs listed in this category conduct modified lab tests considered special or unique, provide interpretation of results, or make alternative soil fertility or organic fertilizer recommendations. This includes labs that test greenhouse media (soil and soiless) and high tunnel soils. Do-it-yourself soil testing supplies are included in this database.

Note to Certified Organic Farmers:
Several of the labs that focus on mineral analysis consult with large-scale grain farmers and recommend commercial fertilizers on a regular basis—the difference being that such fertilizers are used in the context of an alternative fertility program, which may include emphasis on base saturation, nutrient balancing, microbial inoculants, humates, enzymes, and foliar feeding. However, labs will often adjust fertilizer recommendations to fit certified organic standards on request.

Several criteria were used to identify laboratories offering alternative soil testing services of interest to farmers implementing organic and sustainable practices.

Criteria for Labs Specializing in Organic Matter, Humus, Compost, Microbial Analysis:

  • Tests that focus on biological parameters such as soil humus, organic matter, compost, or microbial analysis. Monitoring for non-nutritive parameters is a recent development in agriculture. Such tests were developed in response to increased awareness and attention to total soil health versus mineral analysis alone. Criteria for Labs Specializing in Mineral Analysis and Fertilizer Recommendations:
  • Labs and crop advisors who are associated with alternative farming practices. The advisors are often connected to soil or crop experts who are recognized for their alternative soil testing methods or theories, such as Drs. William Albrecht, Carey Reams, Rudy Ozylins, and Phillip Callahan.
  • Modified lab procedures, unique extract solutions, and specialized lab techniques.
  • Labs or crop advisors connected to a historical or living figure recognized as a contributor to alternative soil testing methods or theories.
  • Labs offering organic fertilizer recommendations.

Qualified organizations not presently included should either use Submit/Update Listings or contact Andy Pressman at ATTRA for inclusion in future updates. Updated information can also be addressed to their attention.

E-mail Andy Pressman or call:


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This page was last updated on: August 3, 2018