Soil testing is one of the most important tools available to growers, landscapers, turf managers, and other land care professionals. It offers a clear snapshot on soil properties—including plant-available nutrient levels—that provides critical information used to guide decisions about fertilization, crop selection, lawn care, and environmental stewardship. However, the accuracy and usefulness of your soil test results depend heavily on the quality and reliability of the laboratory conducting the analysis. This fact sheet focuses on commercial laboratories that test plant-available nutrients and other key soil properties commonly used by growers.
It is important to note that soil-testing laboratories are not regulated by state or federal agencies. As a result, the practices, quality standards, and the accuracy of laboratory results can vary significantly. This is why growers must carefully evaluate a laboratory’s performance, operational standards, and service quality before submitting soil samples. To make informed decisions, growers need confidence that the test results will be high-quality, accurate, and meaningful—and that any accompanying recommendations are based on sound science. This fact sheet provides specific guidelines to help growers select a trustworthy and competent soil analytical laboratory.
What to Look for in a Soil Testing Laboratory?
1. Laboratory Proficiency
The proficiency of a laboratory refers to its credentials and participation in recognized regional or national quality assurance programs. This ensures the lab follows industry standards and compares its performance with other labs to produce accurate and precise test results.
A lab cannot independently assess its proficiency. For this reason, regional and national soil-testing research committees, programs, and other organizations established the North American Proficiency Testing (NAPT) program in 1998. NAPT is backed by Soil Science Society of America (naptprogram.org). The main purpose of NAPT is to provide double-blind check samples that allow laboratories to monitor and improve the quality of their soil-testing data. NAPT also collects and statistically analyzes data from laboratories in their program. Participating laboratories receive a summary of their performance for each soil-test method. Continued self-evaluation and adjustment improves the integrity of participating laboratories’ soil-test results. Anyone requiring soil testing should ask laboratories if they are members of the NAPT program. If a laboratory is a member of the NAPT program, inquire about their NAPT results.
2. Standard and Certified Test Methodologies
The use of appropriate, standardized, and certified analytical methods is essential for producing accurate soil-test results. Research conducted by land-grant universities over the years has led to the development of soil analytical methods tailored to specific regions of the United States. For example, methods designed for analyzing the predominant soils in the southern United States may not be suitable for soils in the north central region.
The North Central Regional Research Committee (NCERA-13) has developed methods that are most effective for soils in the north central region. Reputable laboratories adhere to these recommended methods for testing soil nutrients (e.g., Mehlich-3, Bray, and Olsen). These methods are reviewed in the publication Recommended Chemical Soil Test Procedures for the North Central Region (naptprogram.org/files/napt/north-central-states-methods-manual-2012.pdf) (Nathan & Gelderman, 2012). Laboratories testing Ohio soil should follow the procedures outlined in this publication.
As soil analytical methods evolve, so does our understanding of their applications. Advances in science, technology, and knowledge of soil processes may require that soil analytical methods are updated to improve their accuracy and usefulness. Commercial laboratories are now going beyond traditional fertility tests to include biological, chemical, and physical indicators of soil health using standardized methods (Islam et al., 2021; Karlen et al., 2021). These efforts help meet current and future agricultural and environmental needs. Therefore, it is important to confirm that these testing methods are being used by the laboratory testing your soil.
3. Other Clients
Individuals or organizations requiring soil testing should take the time to consult with their community partners, laboratories they have worked with in the past, and other trusted sources within their network. They should also learn from the experiences of fellow growers and consultants. Doing so helps them gather useful insights and firsthand feedback. This process allows for a better assessment of the credibility, reliability, and overall quality of a laboratory based on the experiences and recommendations of others in the agricultural community.
4. Reliable and Interpretable Results
Soil test results should include standard units of measurement and clear explanations. Ask your laboratory representative about the standard units used for each test parameter. Some laboratories report results in pounds per acre (lb/ac), parts per million (ppm), or pounds per 1,000 square feet (typically used for turf and lawn applications). When comparing results from different labs, ensure the units are consistent. If necessary, a simple conversion may be required. For example, to convert ppm to lb/ac, multiply the ppm value by 2. To convert pounds per acre to pounds per 1,000 square feet, divide pounds per acre by 43.56. To convert percent (%) to lb/ac, multiply by 20,000. Some test parameters may use unfamiliar units, such as meq/100 g for cation exchange capacity. Ask the laboratory representative to explain these units or provide conversion factors if unclear. Avoid laboratories that provide raw numbers without context or recommendations.
5. Categories of Quantity
Some laboratories may classify soil test results into subjective categories, such as very low, low, medium, adequate, high, and very high, though other categories or variations may be used. These categories typically represent a range of test values, but the nutrient concentrations they indicate may vary between laboratories. Ask the laboratory to clearly define the range of test values for each category. Additionally, inquire whether these categories are crop-dependent or based on specific soil conditions (e.g., soil types). For example, a result classified as medium for one crop might be considered very low for another crop.
6. Lime and Fertilizer Recommendations
Ensure that analytical laboratories provide recommendations for chemical fertilizers, nutrients, or lime applications tailored to the specific crop, turf, or landscape use, based on current university research or guidelines. The Tri-State Fertilizer Recommendations for Corn, Soybeans, Wheat, and Alfalfa (FertilityResources/tri-state_info), along with the Ohio Agronomy Guide (extensionpubs.osu.edu/ohio-agronomy-guide-16th-edition), offer guidelines for crops in Ohio soils. These recommendations are based on extensive university research conducted across a variety of soils and growing conditions in Ohio. When consulting with the laboratory representative, inquire about the basis for their recommendations. This will provide an understanding of their lime and fertilizer recommendations for different crops. Additionally, ensure that the recommendations account for your specific soil types, growing conditions, crop rotations, cover crops, and yield goals. Ask if the laboratory includes specific timing for lime and fertilizer applications in their recommendations.
7. Turnaround Time
Before sending soil samples, it is important to contact the laboratory to ask about the time required for sample processing, shipping costs, and how quickly results are returned. Reaching out to past clients listed as a laboratory’s “Other Clients” is also a method that can be used to help assess the lab’s reliability. For soil-test results to be useful—especially during the growing season—they must be delivered within a few days. A good lab should provide standard test results such as pH, lime need, and nutrient levels within two to three business days. However, speed should not come at the cost of accuracy. Reliable labs balance fast service with precise, dependable results.
8. Good Customer Service and Technical Support
A reputable and trustworthy laboratory should provide access to qualified professionals—such as growers, agronomists, soil scientists, or crop consultants—who can answer questions and help interpret test results. Look for a lab that offers quick turnaround times, clear sample submission guidelines, and easy-to-understand reports. It is also helpful to seek recommendations from other professionals in your area based on their experiences. Consistency in results and service over time is a strong indicator of a laboratory’s reliability.
Some laboratories may offer the convenience of delivering results via email or through their website. Additionally, confirm whether lime and fertilizer recommendations can also be accessed online. In certain cases, laboratories may accept sample identification details through the Internet, eliminating the need for a physical sample information form. Most laboratories maintain an email address to facilitate direct and timely communication with laboratory professionals or managers.
9. Visiting the Laboratory
When visiting a nearby commercial laboratory, the manager or a designated representative should be willing to provide a tour of the sample processing and testing areas, explain their analytical methods, and describe the range of services offered. During the visit, take note of the cleanliness and organization of the workspaces used by lab technicians, as these reflect the lab’s operational standards. It is also important to ask how samples are processed, how test results and data are managed, and how quality control and quality assurance protocols are implemented.
10. Reference Check Samples
Determine whether the laboratory routinely uses internal blind and double-blind check samples whenever possible. A blind check sample is one that the technician recognizes as a quality control sample that is taken with an awareness of the acceptable value range for the tested soil parameters. This type of sample helps verify that the testing method and instruments are functioning properly. In contrast, a double-blind check sample has value ranges that are unknown to the technician and is treated as a routine sample. The laboratory manager then evaluates the results to determine whether they fall within the acceptable range with high precision. If the results lack accuracy or repeatability, corrective action must be taken to resolve the issue.
11. Tracking Quality Control
Commercial soil-testing laboratories should routinely monitor their quality control (QC) and quality assurance (QA) procedures by tracking check sample results over time. This practice helps identify variability and maintain consistency in test results. Laboratories should establish clear warning and action limits to promptly detect and address any issues. Ideally, QC charts should be maintained for each soil test parameter and reviewed regularly. Prospective clients are encouraged to request and review these QC charts with laboratory management to verify that the lab upholds high standards of accuracy and reliability.
12. Sample Information and Test Result Forms
Ask the laboratory for examples of the sample information form and the final test results report. Review these documents carefully and request clarification on anything that is unclear. Determine how many soil samples can be submitted per form. Clear and easy-to-follow sampling instructions are typically included in the information form. In addition, sample containers or bags are usually provided—ask to see an example to ensure they meet your needs.
13. Soil Sample Collection Kits
Most commercial soil-testing laboratories provide sample collection kits for their customers. At a minimum, these kits include a sample container or bag and a soil sample information form. Some kits may also include additional instructions or materials. For detailed guidelines on how to properly collect soil samples, please refer to the Ohio State University Extension resources linked at the end of this fact sheet.
14. Field Professionals
Some laboratories employ consultants with backgrounds in agronomy, horticulture, or soil science to assist customers. Before selecting a soil-testing lab, consider visiting or contacting the lab to discuss your soil testing needs and crop management concerns with a qualified professional. If possible, ask to review the consultant’s education and professional credentials to ensure they have the expertise to provide reliable guidance based on your results.
15. Laboratory Test Prices
Soil analysis prices can vary widely among laboratories. Be sure the cost of each test or test package is clearly provided in writing. Check whether quantity discounts are available for submitting multiple samples and whether prices are negotiable or competitive with other labs. Comparing prices and services can help ensure you get the best value without compromising on quality.
16. Other Testing Services
Determine whether the laboratory offers additional services alongside soil testing. Many labs provide routine plant tissue analysis, either as a standalone service or in combination with soil or advanced testing. When used together, tissue and soil analyses can offer valuable insights into nutrient availability and help troubleshoot crop growth issues related to soil fertility. Other commonly available services may include sample collection, manure analysis, lime and gypsum evaluation, compost testing, and water-quality analysis. These complementary services can support a more comprehensive approach to soil and crop management.
Summary
Choosing the right soil-testing laboratory is a strategic investment in your land, crops, and long-term success. A reliable lab provides more than just test results—it offers accurate, research-based insights that support productivity, cost savings, and environmental sustainability. Before submitting soil samples, take time to evaluate potential labs. While OSU Extension does not endorse specific laboratories, your local Extension educator can offer guidance and provide a list of nearby options. If you work with a crop consultant, discuss lab selection with them as well. Do not assume all labs produce quality results—verify their credibility and methods. Once a lab meets your standards, send in a few test samples to confirm consistency and reliability. If satisfied, continue using that lab for future testing to ensure year-to-year comparability. Investing time upfront to choose a trustworthy lab pays off through better decision-making and improved land management. Use the guidelines in this fact sheet to make soil testing a reliable and effective tool for your operation.
Additional Resources
Check out the following resources for more information on choosing a soil analytical laboratory:
- Ohio Agronomy Guide, 16th edition
(extensionpubs.osu.edu/ohio-agronomy-guide-16th-edition/?searchid=0&search_query=agronomy+guide+) - Soil Acidity and Liming for Agronomic Production
(ohioline.osu.edu/factsheet/AGF-505-07) - Soil Sampling, Handling, and Testing
(agcrops.osu.edu/node/3484) - Soil Testing for Horticultural Needs (with a list of suggested soil testing labs)
(ohioline.osu.edu/factsheet/hyg-1132) - Tri-State Fertility Recommendations for Corn, Soybeans, Wheat, and Alfalfa
(extensionpubs.osu.edu/search.php?search_query=974§ion=product)
References
Islam, K. R., Roth, G., Rahman, M. A., Didenko, N. O., & Reeder, R. C. (2021). Cover crop complements flue gas desulfurized gypsum to improve no-till soil quality. Communications in Soil Science and Plant Analysis, 52(9), 926–947.
doi.org/10.1080/00103624.2021.1872594
Karlen, D. L., Stott, D. E., & Mikha, M. M. (2021). Laboratory methods for soil health analysis (soil health series, volume 2). John Wiley & Sons.
wiley.com/en-us/Laboratory+Methods+for+Soil+Health+Analysis+(Soil+Health+series%2C+Volume+2)-p-9780891189862
Nathan, M., & Gelderman, R. (2012). Recommended chemical soil test procedures for the north central region. Missouri Agricultural Experiment Station.
naptprogram.org/files/napt/north-central-states-methods-manual-2012.pdf
Originally written in 1999 by Dr. Maurice Watson, soil fertility extension specialist emeritus, School of Environment and Natural Resources, The Ohio State University.
Revised in 2017 by Keith A. Diedrick, formerly soil fertility research associate, School of Environment and Natural Resources, The Ohio State University; Gary Gao, professor and extension specialist, The Ohio State University South Centers; Robert W. Mullen, formerly assistant professor/extension soil fertility/nutrient management specialist, School of Environment and Natural Resources, The Ohio State University; and Maurice E. Watson, soil fertility extension specialist emeritus, School of Environment and Natural Resources, The Ohio State University.