Frequently Asked Questions

If you have questions about soil testing, see our Frequently Asked Questions below or the Soil Lab Brochure, or Ask Questions directly.

• What soil tests are available?

  Tests offered at the IFAS Extension Soil Testing Laboratory and fee schedule can be found here: Extension Soil Testing.

• Why test my soil?

  Florida has plenty of sunshine and rainfall, but its soils often lack nutrients and other attributes necessary for good plant growth. To improve your soil’s productivity, you should know each of the following soil attributes:

  • pH
  • Lime requirement
  • Status of the major nutrients (P, K, Ca, Mg)
  • Status of the micronutrients (Cu, Mn, Zn)
  • Irrigation water quality

  If you do not have this information, a soil test may help. The UF/IFAS Extension Soil Testing Laboratory (ESTL) tests soil samples year-round. ESTL offers soil tests for homeowners, landscapers, and commercial growers.

• How do I take a soil sample?
  1. Before sampling, develop a soil sampling plan for your field or yard. Samples should best represent the area being tested, so collect samples from the areas that are of the same soil type, appearance, or cropping history. Problem areas or areas that are different should be sampled and submitted separately. From this plan, count the number of samples you will collect. One or two representative samples from each area of the home yard or landscape and 1 to 5 samples from 20 to 40 acres of commercial farms should be collected and sent for analysis.
  2. Contact your local UF/IFAS county extension office for soil sample bags, shipping boxes, and sample submission forms free of charge, as well as advice about sampling. Forms are also available on our website. Assemble all the materials you need to complete sampling according to your plan.
  3. Collect soil from 20 or more spots within each area, mixing these samples in a clean plastic bucket.
  4. Sample from soil surface to depth of tillage, usually 0 to 6 inches.
  5. Spread the composited material on clean paper or other suitable material to air dry. Do not send wet samples.
  6. Mix the dry soil, and place about one pint of soil in a labeled sample bag or to the dotted line on our sampling bag.
• How do I send samples to the lab?
  1. Enter each sample’s identification on its sample bag or bottle and in the “Sample Identification” column. List each sample separately.
  2. Include the test code for each desired test, or circle the cost of the test. Enter costs for the analysis in the cost column.
  3. Crop codes are required to receive lime and fertilizer recommendations. Crop codes can be found on the back of the forms.
  4. Add up the costs of all samples and analyses. Make a check or money order payable to: University of Florida. Checks written in any other name(s) will NOT be honored, will be returned, and will cause an avoidable delay in processing the samples.
  5. Include the completed test information sheet and the check or money order in the shipping box with the sample(s).
• How long before I get the results back?

  Typically, a test report will be emailed/mailed to you within 2 working days after your sample arrives at the Extension Soil Testing Laboratory. Contact your county Extension agent at the number and address listed on your report with any questions about the report and its recommendations. More information about plant nutrient problems may be obtained with a plant tissue test and/or a water test.

• What other tests can I get?

  ESTL offers testing for irrigation water samples, plant tissue, and livestock waste.

  Irrigation Water Test: Hardness and fine sediments can clog the nozzles of irrigation systems and high salt content can adversely affect soil pH and plant health. This is particularly important to those depending on wells for irrigation and those using reclaimed water for landscape irrigation. Reclaimed water may at times contain some plant essential minerals.

  Plant Tissue Test: Determining nutrient concentration in plant tissue samples can be important for perennial plants, crops and home lawns (all plant species that grow more than a season or a year). A plant tissue test is recommended especially when the leaves exhibit any deficiency symptoms or when growth is inhibited. In the case of perennial plant species, a soil test alone may not provide the necessary insight on nutrient deficiencies. Certain physiological imbalances may occur, either inhibiting nutrient uptake from soils or use after uptake within the plants, despite application of nutrients to the soils as per the recommendations.

  Additional diagnosis and nutrient adjustments may help overcome the deficiencies and growth imbalances. The need for water and/or plant tissue tests can be ascertained along with obtaining additional information on any of the tests by contacting your local extension agent or Master Gardener at your local UF/IFAS Extension Office.

• Who should I make the check payable to?

  All checks should be made payable to University of Florida.

• Do I need to have a soil test done?

  Your local extension agent will be able to help you decide if a soil test is appropriate for your case.

• Do I need to dry the samples?

  Both soil and plant tissue samples should be air dried and placed into paper bags prior to shipping. Do NOT use plastic bags for leaf or other plant tissue samples.

• Who is to send the samples?

  The customer is responsible for sending the samples to the lab. However, you can seek assistance from the local county extension office on submission forms, how to choose the right test, and our pricing.

• Will the extension office mail the soil sample for me?

  A few county extension offices will send the samples on your behalf. However, please check with your local county extension office to see if this service is available.

• What is being tested (pH/lime vs. fertilizer)?

  We have different test packages test for different purposes. Your local county extension office can help guide you to the test appropriate for your case.

• My plants are not doing well. Should I do a soil test?

  The reason your plants are not doing well may or may not be soil-related. Your local extension agent will be able to help you if a soil test is appropriate for your case.

• What do the results mean?

  The results of your soil test tell estimate the availability of nutrients in your soil. The test report will tell you the rate (in lbs/1000 sq ft or lbs/acre) of the nutrients you will need to apply for your particular crop or grass species. In some cases the recommended rate will be zero.

• Will a soil test tell me what chemicals or diseases are in the soil?

  No. The ESTL does not test for diseases or chemicals that may be in the soil.

• Is there a test available for nitrogen (N) in soil samples?

  No. We do not test for nitrogen in soil. Such a test would be unreliable because of continuous, natural, and rapid changes that occur between chemical forms of nitrogen in the soil.

• If there is no soil test for nitrogen (N), then how are the recommendations made for N for my crop or grass species?

  The N recommendations are derived from research data from studies conducted on N fertilizer requirements of crops and grasses. Therefore, a soil test is not required if you are only looking for N recommendations. Your local county extension agent or Master Gardener may be able to look up and provide you the N fertilizer amount recommended from the UF/IFAS Extension Publications.

• If I live in Miami-Dade or Monroe County, do I need a soil test done?

  Yes. A soil test is the most scientific way of assessing the soil nutrient status. However, in Miami-Dade or Monroe Counties, soil test interpretations are limited due to the extremely high amounts of lime rock in the soil. The report may contain recommendations for potassium and magnesium but you may not receive any recommendation for phosphorus. Recommendations for nitrogen will be included in the reports, although N recommendations are not derived from a soil test. Please consult with your local county extension agent for additional details.

• How often should I test the soil in my yard?

  A routine soil test should be done once every 2 years if the landscapes plants and lawns are managed and expected to perform optimally.

• When should I expect to receive my results, and can my extension agent help me interpret them?

  If an email address is provided, the results should be available in about 2 working days after the laboratory receives the soil. If the soil sample is wet when received at the lab, it may take additional time for the results. Results are always emailed to the county extension office immediately. If no email address is provided, results will be sent via regular mail in 2 working days and may take longer to be received.

• Can I use a plastic bag instead of a paper one for soils?

  A plastic bag may be used only when the soil sample is dry. This will help prevent any growth of mold. However, paper bags are always preferred for both soils and plant or leaf tissue samples. Free soil sample bags are available at your local county extension offices.

• Will a soil test determine if nematodes are a problem?

  No. The IFAS Soil Testing Lab does not test for nematodes. The IFAS Nematology Assay Lab can test for nematodes.

• How much (volume) soil do I need to send?

  About a pint of air-dried soil sample is required by the lab. If you have one of our standard sample bags, please fill up to the dotted line.

• Can I hand-deliver my samples to the lab?

  Yes, our laboratory is open from 8 AM to 12 noon and from 1 PM to 5 PM, Monday thru Friday, during a regular work week.

• How do I package the sample?

  The free priority mailing boxes from the US Post Office can be used to mail samples to the Lab. Free soil sample bags are available at your local county extension office.

• How do I contact the lab if I have questions?

  Our phone number and email address are on the soil sample submission form. Or, you can send an inquiry through our website: https://soilslab.ifas.ufl.edu
  
  More details can be found here.

• My grass is not growing well, or plants are dying. Should I get a soil test?

  The reason for poor growth may or may not be related to soil fertility. Your local extension agent will be able to help you if a soil test is appropriate for your case.

• What is a soil extractant?

  A soil extractant is a reagent solution containing specific chemicals that is mixed with your soil sample. The extractant mimics the root extraction of nutrients in the soil and pulls the nutrients from the soil sample into soil solution. Different extractants are used for different soils in Florida.

• What is the extractant used by the UF/IFAS lab?

  The soil extractant used for acid-mineral soils in Florida is called Mehlich-3. Currently, for high pH or alkaline soils the extractant used is Ammonium Bicarbonate-DTPA (AB-DTPA).

• How are soil test results interpreted?

  The following chart interprets ranges of soil test nutrients into "low," "medium," and "high" categories for agronomic and horticultural crops grown on acidic soil (soil pH lower than 7.3). The values are in parts per million (ppm) using the Mehlich-3 (M-3) extraction method:

  Nutrient	Low	Medium	High
  P	≤ 25	26-45	> 45
  K	≤ 35	36-60	> 60
  Mg	≤ 20	21-40	> 40

• What is A-E Buffer value printed on the reports?

  The A-E Buffer value refers to the Adams-Evans Buffer test we run to determine the amount of lime required to raise the pH of your soil to a specific level. A-E Buffer pH is different from the soil pH value.

• Can we determine the lime requirement simply from the soil pH test?

  No. It would be erroneous to try to estimate or calculate the lime requirement using just the soil pH value. Lime requirement can be determined only using the Adams-Evans Buffer test in conjunction with the soil pH value. So, soil pH alone should NOT be used to determine or predict the amount of lime required to raise soil pH.

• My pool water discharged into my yard. Should I do a soil test to see why my grass is dying?

  These two things may not be related. Your local extension agent can help you decide if a soil test is appropriate in your case.

• For a pasture grass like bahiagrass, should I choose the Low, Medium or High nitrogen option?

  Unless the grass pasture is managed intensively, hayed, is commercially and economically viable, and/or is irrigated, the "High N" option is not recommended. For grazing purposes, the "Low N" option is usually sufficient. If the grass performance is poor and needs improvement, the "Medium N" option can be considered.
  
  The different nitrogen options for the bahiagrass test are explained in UF/IFAS publication SL-129, UF/IFAS Standardized Fertilization Recommendations for Agronomic Crops.

• I can't find bag with a specific N-P2O5-K2O nutrient ratio- for example- 2-1-2 or 0.25-0- 0.35, etc. Should I look for this ratio when purchasing fertilizer?

  Fertilizer recommendations are provided for individual nutrients, so they cannot always be found in "off the shelf" bagged fertilizer. You will either need to find single-nutrient fertilizers and combine them or find a ratio that is closest to the recommended rates. Use caution to avoid applying excessive rates of nitrogen or phosphorus, and be aware of local fertilizer bans that depend on the time of year. Your local county extension office can help you make the right choices that will minimize environmental impacts.

• Why is the soil pH so much different that when I had it tested in years past? It was usually 6.5-7.0 and now it is 5.0.

  The answer could be multiple factors. Soil type, management practices, fertilizer source choices, use of soil amendments, irrigation, and weather factors can all cause soil pH changes with time. In the southeastern US, if "basic" nutrients such as calcium, magnesium, and potassium are not applied regularly to soils producing crops or aesthetic landscapes, soil pH may decrease.

• Are there any labs that can test for substances like pesticides, chemical contaminants, heavy metals, etc.?

  Yes. Commercial laboratories exist that may provide tests and services that the UF/IFAS lab cannot provide. A quick internet search can identify these labs. Also, a list of labs is available on Florida Department of Environmental Protection web site for certified laboratories: https://fldeploc.dep.state.fl.us/aams/analyte_search.asp

• Why can’t plant diseases or nematodes be tested at the UF/IFAS Soil Testing lab?

  The UF/IFAS Soils Lab provides nutrient analyses for soil, plant tissue, water and manure/composts/other organic waste samples. Samples for plant diseases testing should be sent to the IFAS Plant Diagnostic Center or for nematode testing to the IFAS Nematode Assay Lab in Gainesville.