Choosing a Laboratory for Nutrient and Soil Health Testing

Soil testing provides key information about soil nutrient availability. It is also increasingly used to identify the soil's biological and physical characteristics to give a complete picture of overall soil health. Farmers, gardeners, and landowners can use soil testing data to optimize their nutrient management plans. Implementing recommendations based on soil test data prevents under- or over-application of lime and fertilizers. In Ohio, there are several laboratories to choose from, all of which offer a variety of soil and other valuable tests. This fact sheet lists labs in or near Ohio, and important factors to consider when choosing the right lab for you.

Factors to Consider in Selecting a Lab

Consistency

Consistency in sample collection and analysis is key to tracking soil fertility or soil health changes over time. Using the same soil testing lab and analyses enables you to compare numbers from one sampling period to the next to monitor progress. It is also essential to use consistent sampling methods (soil depth, time of year, etc.).

Cost

Soil testing packages are competitively priced, and although pricing is important, using cost alone as the selection criteria is a misguided approach. A quality lab does not cut corners, ensures that qualified personnel provide data, and answers your questions. Most labs offer discounts based on sample volume.

Standard Soil Test Package

Labs offer a “standard” soil testing package that typically includes pH, cation exchange capacity (CEC), and availability of nutrients such as P, K, Ca, and Mg. Some labs may also include total organic matter and micronutrients in their “standard” package. Be aware of what tests are included in the standard package when comparing prices between labs. A cost comparison between labs should compare the total cost for all test results you require for your operation.

Quality Control Measures

State or federal agencies do not regulate soil-testing laboratories in Ohio for most of the agronomic tests listed. However, laboratories can enroll in voluntary enroll in third-party proficiency programs such as the North American Proficiency Testing (NAPT 2022), Agricultural Laboratory Proficiency Program (ALP 2022), or Agricultural Laboratory Testing Association (ALTA 2022) to ensure accuracy and precision in sample results. The gold standard for a lab is to be a certified member of the Agricultural Laboratory Testing Association (ALTA 2022), which has strict standards. At a minimum, laboratories should be conducting internal self-evaluation measures such as standard checks or internal reviews.

Staff Expertise

Any lab can generate numbers, but if you need help interpreting what reported numbers mean, the lab must have experienced agronomists or technicians on staff to help provide context and walk you through your soil test report.

Methods of Analysis

Standard soil testing methods and recommendations vary regionally. For Ohio soils, it is best to choose a lab that follows recommendations from the NCR-13 Soil Testing and Plant Analysis Committee (Eliason 2015). This committee of university scientists has developed methods appropriate to soils in the Midwest that are used as the basis of fertilizer and lime recommendations.

Convenience

Soil testing should not be complicated; a good lab should help make it easy. Does someone pick up the phone when you call? Or, if you prefer email, do they respond in a timely fashion? How do they bill, and what forms of payment are accepted? How helpful is their website?

Fertilizer and Lime Recommendations

Soil test reports can come with fertilizer and lime recommendations, but labs are not obligated to use university recommendations. Here are a couple of questions you should ask about recommendations. First, what is the basis of the lab’s recommendations? Second, will they provide vetted university recommendations upon request? An example of a university recommendation is the Tri-State Fertilizer Recommendations (Culman 2021)

Data Management System

Many labs have convenient websites where you can log into your account to generate sample submission forms, review results immediately when they are available, and even view results from past years. If web access is not available, ask if test results are available in electronic formats compatible with your agricultural software.

Turnaround Time

Most labs return results within a few days of receiving your soil. If getting data back quickly is essential to you, ask about typical or guaranteed turnaround times.

Quick Guide to Soil Test Abbreviations and Definitions

Cation Exchange Capacity (CEC). Measures the amount of positively charged nutrients (such as Mg, Ca, K) that your soil can hold. Soils with higher clay content have higher CEC values.

pH. Measures H (hydrogen) content of the soil and is a key factor to nutrient availability.

Buffer pH (or acidity). Measures exchangeable H and is used to determine the amount of lime needed to reach target pH.

Extractable nutrients. P (phosphorus) and K (potassium) are most often reported. Labs often report Ca (calcium), Mg (magnesium), and Na (sodium). Other nutrients may be reported on request such as Mn (manganese), Zn (zinc), B (boron), Cu (copper), Fe (iron), Al (aluminum), and S (sulfur).

Heavy metals. Heavy metals are a possible concern on urban or reclaimed soils, where biosolids have been spread or areas where previous owners used products such as pesticides or lead-based paint. Pb (lead), Cd (cadmium), Cu (copper) and As (arsenic) are examples of heavy metals that may contaminate soils. Learn more about heavy metal screenings from the Ohio State Damaged Soil Investigation, Restoration, and Treatment Laboratory at dirt.osu.edu.

Nitrogen. Nitrogen is not often measured in standard soil packages since environmental factors impact available nitrate. However, some labs offer estimated nitrogen release tests or measure plant-available forms NO3 (nitrate) or NH4 (ammonium) in the soil.

Organic matter. Organic matter is usually defined as total organic matter, or total carbon. It is a measure of the soil's natural amount of organic matter or carbon, which can provide numerous benefits, including a slow-release nutrient reserve, decreased water stress, support for microbial and soil life, and protection from soil compaction.

Active organic matter (POXC). Measures the portion of organic matter most likely to interact with plants and fertility.

Solvita test. This soil respiration test measures the soil's biological activity.

Haney test. This test measures how hospitable soil is for microbial life. Tests include measuring soil nutrients available to soil microbes, soil respiration (microbial breathing), water-soluble organic carbon, organic nitrogen, C:N ratios, and NO3, NH4, and other key nutrients. The results indicate the amount of food readily available to soil microbes and is sensitive to measuring root exudates and decomposed organic material.

Bulk density and aggregate stability. These laboratory tests measure soil structure and compaction.

Soil texture (or particle size analysis). A measurement of the amount of sand, silt, and clay in your soil, which dictates soil type.

Table 1 (click image to download PDF). Soil testing labs in or near Ohio.

Table 1: (PDF Download) Soil Testing Labs in or near Ohio

Additional Services

While some laboratories focus solely on soil testing, others offer further tests that may be useful to your operation. For example, plant-tissue analysis can be used with soil testing to isolate fertility problems in the field. In addition, farms using manure, compost, soilless mixes, nutrient solutions, or irrigation water should evaluate these inputs for their impact on nutrient management.

Ask Around

Consult with county educators, other farmers, and crop consultants on labs that they use. Additional time and effort spent selecting a quality soil-testing laboratory will pay off. Do not assume the laboratory gives quality test results or has responsive customer service. Save yourself trouble by finding out for sure.

Disclaimers: Inclusion in this publication does not constitute an endorsement by The Ohio State University. Please check with individual laboratories for updated information on tests offered, prices, and policies. Fact sheet information was last reviewed on 07/21/2022.

Resources

Ohio State University Extension. n.d. "Fertility Factsheets, Bulletins and Tools." Accessed July 13, 2022.
agcrops.osu.edu/FertilityResources

References

ALP (Agricultural Laboratory Proficiency Program). n.d. Accessed July 13, 2022.
alpprogram.net/home

ALTA (Agricultural Laboratory Testing Association). n.d. "Certified Labs." Certified Labs. Accessed July 13, 2022.
alta.ag/certified-labs

Culman, Steve, Anthony Fulford, James Camberato, and Kurt Steinke. 2021. Tri-State Fertilizer Recommendations. Columbus: The Ohio State University.
extensionpubs.osu.edu/search.php?search_query=974&section=product

Eliason, R., R. J. Goos, and B. Hoskins. 2015. "Recommended Chemical Soil Test Procedures for the North Central Region." Columbia: University of Missouri. PDF (Portable Document Format).
extension.missouri.edu/media/wysiwyg/Extensiondata/Pub/pdf/specialb/sb1001.pdf

NAPT (North American Proficiency Testing). 2022. "NAPT Program."
naptprogram.org