Why should I soil test?

    * Soil testing is an important diagnostic tool to evaluate nutrient imbalances and understand plant growth.

    * The most important reason to soil test is to have a basis for intelligent application of fertilizer and lime.

    * Testing also allows for growers and homeowners to maintain a soil pH in the optimum range (6.0-7.0), which keeps nutrients more available to the plant for growth.

    * Protection of our environment - We cannot afford to pollute our surface and ground waters by indiscriminate application of phosphorous or nitrogen fertilizers, for example.

    * Cost savings - Why apply what you don't need? Soil test results provide information about the soil's ability to supply nutrients to plants for adequate growth, and are the basis of deciding how much lime and fertilizer are needed.

What is being tested in a soil sample?

    * The regular soil test includes determination of soil pH, available phosphorus, potassium, calcium, and magnesium levels as well as recommendations for lime and fertilizer. Other soil tests are available at supplemental costs, such as, organic matter, zinc-manganese, etc.

How do I know if the test results are accurate?

    * The lab takes various quality control measures to ensure the accuracy of results. Soil with predetermined nutrient levels is tested every 20 samples to provide an accuracy check.

    * MSU recommends testing soil every 3 years. If recent results are not consistent with past results, notify your county MSU Extension agent or the lab within one month to rerun the questioned test.

Why doesn't the regular MSU soil test include nitrogen analysis?

    * Soil nitrate levels are the best indicator of nitrogen availability. Because these levels fluctuate widely depending on rainfall and soil temperature, the best time to take soil nitrate samples in while the crop is growing. within two weeks of supplemental nitrogen applications.

    * A soil sample taken months ahead of this time will not provide an accurate measure of the nitrogen available to the plants.

How does the lab make nitrogen recommendations?

    * Nitrogen recommendations are based on the past and present crops grown plus the yield goal for the crop to be grown.

    * Less nitrogen is recommended when the previous crop was a legume, because they add nitrogen to the soil.

Where can I get my soil samples tested?

    * Take the soil sample to your county MSU Extension office, located in your county seat.

    * Bring the sample directly to the MSU Soil and Plant Nutrient Lab, room A81 (basement), in MSU's Plant and Soil Science Building, which is located on the south west corner of Bogue and Wilson.



How soon should I receive test results?

    * You should receive test results in about two weeks. The analysis take 3 to 5 working days from the time the lab receives the samples.

    * The results are then mailed to your county MSU Extension agent for interpretation.

    * Remember MSU recommendations are in pounds of nutrient needed, not pounds of fertilizer to be applied!


Please select a question from the list:

   1.
      Why use the LSU AgCenter Soil Testing and Plant Analysis Laboratory (STPAL)?
   2.
      How do I take a soil sample?
   3.
      When and how often do I need to collect soil samples?
   4.
      How much sample do I need to send to the Lab for testing?
   5.
      What happens if I do not have an LSU AgCenter sample carton/box?
   6.
      Do I need to state the specific crop to be grown for fertilizer recommendation?
   7.
      What condition of soil sample should I mail to the Lab?
   8.
      What form of payment should I use to pay for tests?
   9.
      Is it OK to submit the soil sample through nursery or hardware stores?
  10.
      How do I convert fertilizer or lime rates for larger lands to small areas, single rows or potted plants?
  11.
      Why do I need to run a plant diagnostic analysis?
  12.
      How do I take a plant sample?
  13.
      What types of water samples can I send to the Lab for analysis?


Answers to Frequently Asked Questions (FAQ):

   1.
      Why use the LSU AgCenter Soil Testing and Plant Analysis Laboratory (STPAL)?
      The LSU AgCenter STPAL offers a variety of soil tests and plant tissue diagnostic tests to meet your planning needs for profitable production. Fees charged at STPAL are cheaper than any commercial laboratory on similar tests (View offered tests and fee schedule). The STPAL offers adequate fertilizer recommendations based on latest results of Louisiana-specific research. We do not recommend fertilization that wastes your money and may cause adverse environmental consequences. In addition, STPAL uses a modern quality assurance program to improve its analytical process for accuracy and efficiency. The STPAL is the only Louisiana laboratory that participates in the well-recognized North American Proficiency Test (NAPT) program and maintains an acceptable level of proficiency (View our NAPT performance).

   2.
      How do I take a soil sample?
      In general, soils that differ in appearance, crop growth or past treatment should be sampled separately, provided the area is of such size and nature that it can be fertilized separately. For each sample, collect soil from 10 or more places in each sampling area in a zigzag fashion so as to make a representative sample. Mix thoroughly before filling a sampling carton or container to be mailed to the Lab. One soil sample should represent 10 acres or less. Avoid sampling directly in the fertilized band. Proper sampling depth depends on the kind of crop you plan to grow. We recommend that for pasture, turf, established orchards and minimum tillage, you take top 2-3 inches of soil and for cultivated crops, you collect upper 5-6 inches of soil. Click here for an illustrated version of soil sampling.

   3.
      When and how often do I need to collect soil samples? You need to take soil samples every 2-3 years to ensure that you update field fertility conditions. We recommend that you collect and submit samples 3-5 months before your projected planting date to ensure that you have plenty time to plan your liming and fertilization program for the upcoming season.

   4.
      How much sample do I need to send to the Lab for testing?
      You need to send in at least 1 pint of soil for each sample to the Lab for analysis.

   5.
      What happens if I do not have an LSU AgCenter sample carton/box?
      You can contact your parish extension office for sampling cartons. If you are not able to get the cartons, you can send in your sample in a heavy-duty plastic zippered bag.

   6.
      Do I need to state the specific crop to be grown for fertilizer recommendation?
      Yes. It is absolutely important to specify what crop you plan to grow so a correct recommendation can be generated for your sample. The back sheet of the Soil Test Request Form lists available crops.

   7.
      What condition of soil sample should I mail to the Lab?
      In general, you can send in any soil sample. If you send samples that are very wet, you may consider using a plastic bag rather than a carton to contain your sample. Very wet soil samples can damage cartons and cause a loss of your sample in delivery process before reaching the Lab.

   8.
      What form of payment should I use for tests?
      You can enclose a money order or check for payment. Please do not mail cash to the Lab.

   9.
      Is it OK to submit the soil sample through nursery or hardware stores?
      Soil samples may be submitted through local nursery stores where they offer such service. For quicker turn-around, please drop your samples at your local parish agent's office or mail directly to the Lab. There have been instances in which the Lab never received clients’ samples mailed by stores.

  10.
      How do I convert fertilizer or lime rates for larger lands to small areas, single rows or potted plants?
      Fertilizer recommendations are usually given in pounds per acre and lime in tons per acre. For fertilizing small areas, single rows or potted plants, it is necessary to make conversion to suit your needs. You can click here to view conversion tables.

  11.
      Why do I need to run a plant diagnostic analysis?
      Plant analysis provides immediate diagnosis of nutrient deficiency, toxicity or imbalance. It serves as a supplemental tool to soil tests. It can monitor the effectiveness of your adopted fertilizer practices.

  12.
      How do I take a plant sample?
      Plant samples should be taken at early growth stages sensitive to nutrient requirements. Depending on crops, different parts of plant are taken for diagnostic analysis. General guidelines on what to sample are provided in Table 1 for field crops and Table 2 for vegetable crops. For crops you do not find in these tables, you may sample the youngest but fully mature leaves. Avoid soiled, diseased and insect-damaged or mechanically damaged plants and exclude dry and dead tissue. Please mail your plant samples in paper bags (no plastic bags) directly to the Lab.

  13.
      What types of water samples can I send to the Lab for analysis?
      We run water samples for agricultural and aquacultural applications.


1. What does the Soil Testing Laboratory do?

    We provide routine soil testing and fertilizer recommendations for the purpose of evaluating soil fertility and soil pH level and/or problems due to excessive salts or fertilizer materials

2. Will a soil test help diagnose problems with my plants?

    Problems with plants may be caused by factors other than soil fertility, e.g. disease, insects, insufficient light, soil moisture or compaction, or climatic conditions. An evaluation of soil fertility and pH is an important first step in diagnosing problems. If soil fertility is not found to be a problem, then the other factors affecting plant growth should be evaluated to determine possible causes (See #3).

3. Where can I go for more help?

    Check out our Resources page for a complete list of county and state organizations who can offer further help.

4. How long does it take for the Laboratory to analyze my samples?

    It usually takes three to five days for the Laboratory to process your soil samples.

5. 

6. Should I test for trace elements or lead?

    Trace element tests may be useful in some professional operations for special problems. Testing for lead is only useful if the soil is suspected to be contaminated with lead.

7. When should I request the soluble salts test?

    The soluble salts test is only necessary under specific conditions.

http://www.css.msu.edu/SPNL/Faq.cfm