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Frequently Asked Questions



How do I get my soil tested?

Soil must be sampled by you according to instructions provided (with soil test kit, or online). Send the soil sample to the Rutgers Soil Testing Lab (STL) for analysis with a Soil Test Questionnaire; use a soil test kit or other packaging, or deliver in person. When testing is completed, a soil test report will be generated and sent (by email as PDF, or by US Postal Service). The report will include recommendations if planting/crops were indicated on the Soil Test Questionnaire. See How to get your soil tested, where you will find Sampling Instructions and Soil Test Questionnaires for different situations; choose the set most appropriate to your planting/crop situation.

What is a soil test kit? Where do I get a soil test kit?

A soil test kit is comprised of Soil Sampling Instructions, a Soil Test Questionnaire, and a mailer (cotton bag with plastic insert attached to an envelope), and it is available at county offices of Rutgers Cooperative Extension at a cost that covers the soil fertility test fee. Additional test requests can be accommodated with appropriate payment. Sampling Instructions and the Soil Test Questionnaire are provided in the envelope, and the completed questionnaire should be inserted back into the envelope. Obtain a soil sample by following the Sampling Instructions and insert it into the plastic bag and secure into the cotton bag. This package can be mailed as-is; take to your local post office for correct postage. If you are submitting more than one sample, the cost may be less by boxing them together. Drying your soil sample(s) before packaging may also decrease mailing cost.

What is a Soil Test Questionnaire?

A Soil Test Questionnaire is the form that is used to submit a soil sample. Besides basic client contact information, the questionnaire must indicate the test request, any payment information (if needed), and the type of planting for which fertilizer/limestone recommendations are needed. Select no more than two (2) planting types/crops for recommendations. For most appropriate recommendations, please be sure to complete the Soil Test Questionnaire (including new or established and other information requested). Please be careful to write legibly, especially in the email address field.

Do I need a soil test kit to get my soil sample(s) analyzed?

A soil test kit is not required to have your sample(s) tested; instead you can follow soil Sampling Instructions on our website, sending required payment with the sample(s) and completed Soil Test Questionnaire (also available online) in a box or padded envelope.

How much soil is needed for a soil test? How much for Greenhouse/potting media or compost?

As Sampling Instructions describe, two cups (1 pint) of soil is requested; if you have a soil test kit, fit the plastic insert into the cotton bag and fill to capacity (if you follow Sampling Instructions, you should have more than enough to fill the bag); be sure to secure the inner and outer bags carefully. If you are not using a soil test kit, a sandwich-size plastic bag can be used, fill at least half-full. Gravel and stones (as well as roots, wood, mulch, etc.) can be removed in most cases, because they will be removed before (most) analyses anyway and only take up space and add weight to your package.

But if you are requesting a Topsoil Evaluation or sieve analysis, do not remove gravel/stones, and providing an extra "cup" of soil is helpful in providing a representative sample to determine the gravel content. For the technical Topsoil Specification Test, it is beneficial to lab staff to have even more (a gallon-size bag filled halfway).

For greenhouse media or compost, a gallon-size bag full is most appropriate. When submitting these types of samples, be sure to use the Organic Media Questionnaire.

What is included with a standard Fertility test (including pre-paid with soil test kit)?

The Fertility Test includes: Soil pH and Adams-Evans buffer pH (aka Lime Requirement Index), and Nutrients extracted by Mehlich 3: phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), copper (Cu), manganese (Mn), zinc (Zn), boron (B), and iron (Fe). Note nitrogen (N) is not included. If plantings/crops are indicated on page 2 of the Soil Test Questionnaire, recommendations (for limestone and fertilizer) will be provided, including the nitrogen (N) requirement for the crops indicated.

The standard Fertility test cannot be used for organic matter-based media, such as compost or potting soil. The standard Fertility test uses a chemical extractant that is calibrated for use with "natural" mineral soils and is not appropriate for high-organic content soils (for example, more than 20% organic matter by weight). This may apply to raised beds that are composed of compost and/or imported "organic topsoil". For greenhouse media or compost samples, be sure to use the Organic Media Questionnaire for appropriate test request and fee.

Why isn't nitrogen (N) analysis included in a basic soil fertility test?

Nitrogen (N) content is not part of the standard soil test. Inorganic forms of N, which are available to plants, are short-lived in soil, with values changing constantly, and sometimes rapidly, throughout the growing season. Because of this, nitrogen recommendations are more reliably based on seasonal requirements of the crop. Soil test reports do include recommendations for fertilizer N, phosphorus, and potassium (N-P2O5-K2O) requirements.

If plant-available nitrogen levels in soil are of special interest, the inorganic nitrogen test can be requested at additional cost for a "snapshot" of nitrate-N and ammonium-N levels in the soil at the time sampled.

Why are recommendations generated for only two planting types/crops?

As sampling instructions indicate, areas used for different types of plants should be sampled separately since the areas are likely to be different in the first place. Mixing subsamples from two or more different areas only muddies the analytical data, representing none of the areas accurately and result in inappropriate recommendations (garbage in, garbage out). So the soil sample should be representative of one defined area, ideally with limited number of plant types. 

Why didn't I get recommendations on my soil test report? Or I received recommendations for a different crop/planting than I need.

When a crop/planting (or no more than two) is checked on the Soil Test Questionnaire, a recommendation for soil pH adjustment and fertilizer amendment will be provided. If the Soil Test Questionnaire is not completed to include a crop/planting, lab staff may provide "default" recommendations or may make a guess based on sample ID, for example. For most appropriate recommendations, please be sure to complete the Soil Test Questionnaire (including new or established and other information requested).

Note that some crops/plantings do not have recommendations programmed into the soil test database program.

What other testing services are offered by STL?

A complete list of services and fees is provided here: Services and fees. Notice that combination tests are organized by different uses (Landscape, Farm, Athletic Field/Golf Course, Technical, Greenhouse & Compost), and individual tests are listed as well.

What if I have questions about the Soil Test Report?

For most users, Soil Test Reports are copied to the local Cooperative Extension office, and so your report is available to Extension staff to view and discuss results, recommendations, and other issues related to plant health. The telephone number for your county Cooperative Extension office is provided on the soil test report (Referred to: Rutgers Cooperative Extension of [your local] County).

Does the lab test compost?

Yes. The basic compost test for small, backyard composting provides basic information to assess quality for general landscape use. The technical compost test is appropriate for larger scale and commercial composting operations, and includes many indices required to assure good quality product.

Does the lab test potting soil?

Yes. Find the Greenhouse (soilless) growing media option under the heading "Organic Media". The Saturated Media Extraction procedure, most appropriate for high-organic content soils, is used. This may apply to raised beds that are composed of compost and/or imported "organic topsoil" (for example, more than 20% organic matter by weight).

Do you test for disease organisms in soil?

No. The soil is a natural habitat for millions of organisms (per gram), many of which are benign or even beneficial to plant health. Some microbes co-exist with plants without causing disease but become pathogenic under certain circumstances (plant injury or other stress, environmental conditions, etc.). Also, pathogenic organisms may be in the soil but not necessarily active. These are reasons that this soil microbial analysis may not be helpful.

IF you are having a plant health problem and need a diagnosis for proper treatment, please find information about Rutgers Plant Diagnostic Laboratory. For most situations, plant specimens are needed for diagnosis by plant health diagnosticians; one exception is for soil-borne nematodes. Plant, insect, and fungus/mold identification are other services provided by Rutgers Plant Diagnostic Laboratory.

Does STL test for lead? Does the lab test for arsenic/chromium/heavy metals/contaminants? How about oil?

Lead (Pb) is the only contaminant currently analyzed at STL. It is referred to as "lead screening" in the list of Services and Fees because the method is not EPA-approved, but it has a strong correlation to EPA methods. Certain "heavy metals" (Mn, Cu, Zn, Fe) are also plant (and human) nutrients and are analyzed and reported on the soil test report; the values however are not "total" values but Mehlich-3 values extractable (correlated to plant availability).

While contaminants are outside of this lab's focus, new technology for analyzing a wide range of element (total) concentrations may allow the lab to offer this screening in the future. However, certified environmental testing laboratories should be consulted for most rigorous standards.

What analytical methods are used by the lab?

Most of the methods used by Rutgers Soil Testing Laboratory are described in USDA's Northeastern Regional Publication No. 493, Recommended Soil Testing Procedures for the Northeastern United States

Some procedures used here are not described in this publication, but test methods may be described in Soil Science Society of America's "Methods of Soil Analysis" volumes, or similar (modifications for routine testing labs are sometimes necessary).  In some cases methods are described by product or equipment manufacturer, for example, but all methods have been reliably used for soil science research applications.

What quality control measures are used at STL?

  • Daily calibration of instruments, drift checks
  • Reference samples
  • Soil Science Society of America/North American Proficiency Testing program

When will I get the results of the soil tests?

Turnaround time varies based on many factors, including number and types of analyses requested, number of other samples in line for same tests, staffing, holidays, equipment maintenance. Target turnaround time (TAT) for the basic fertility test is one week or less from the date the sample is received. Another target TAT is two (2) weeks for a Topsoil Evaluation. These are estimates, not guarantees. Additional test requests may increase TAT further.

For quickest delivery of a soil test report, provide your email address on the Soil Test Questionnaire.

How will I get soil test results?

If you provide an email address on the Soil Test Questionnaire, your soil test report will be sent electronically as a pdf attachment from "soilslab" as soon as testing is completed and reports are generated. Depending on your email security settings, the email/report might be filtered into your spam/junk mail folder instead of the Inbox. Whitelist in your email program to assure delivery to the Inbox, or be sure to check your spam/junk mail folder before deleting its contents.

If you prefer to receive your soil test report by mail, leave the email address line blank.

Note the soil test database allows for either print-to-mail or email reporting options, and only one email address can be accommodated. (A report that is emailed can easily be forwarded to another address, of course.)

What does "Soil Health" (Solvita® soil CO2-burst) test tell us about soil health and management?

CO2 respired from dried/re-wetted soil sample (during 24-hour incubation) provides a measure of microbial activity as soil organic matter is decomposed; this is often used as a biological indicator of Soil Health. When soil microbial activity is low under laboratory conditions, it suggests low food/energy source and/or confounding chemical or physical conditions. Amendment to increase organic matter content, as well as addressing any chemical or physical problems, is the general recommendation when soil microbial activity is low. However, a very high level of activity that also indicate/lead to soil health problems.

The microbial respiration also provides an estimate of nitrogen released from organic matter, potentially available to plants, to credit against nitrogen fertilizer requirement/recommendation. (Subtract the credit from the automatically-generated N recommendation). Notice this may change the fertilizer ratio suggested.

What is the difference between total nitrogen and inorganic nitrogen? Which do I need?

In most cases of soil fertility testing, nitrogen (N) analysis is not required. Fertilizer N recommendations are not based on a dynamic factor such as measured available N. Instead, a fertilizer N recommendation is based on the type of crop and time of year (growth stage). If a "snapshot" of plant-available N concentration in soil is desired, inorganic N analysis (for nitrate-N and ammonium-N, parts-per-million units) should be requested; be aware that these values can change relatively quickly in response to microbial and plant activity, rainfall or irrigation, volatilization, and other soil conditions. Total N values (percentage) represent predominantly N combined in organic molecules of soil organic matter (humus) and are not as variable. Some (usually relatively small) portion of the total N can be released over time by microbial decomposition of the organic matter to provide plant-available N. See Soil Health/Solvita® CO2-burst test.