Sampling Instructions

Each sample type has a unique sampling procedure to ensure the best and most accurate results. These details are outlined below.

When submitting your samples please be sure to include your name, address, phone number, sample ID and if possible your email address.
If you have any questions please don’t hesitate to ask! 

  1. Soil samples can be collected using a clean, rust free probe, spade or shovel. A soil probe allows samples to be taken from an accurate depth. If using a spade or shovel, a furrow slice may be taken. Remove all vegetation and residue prior to sampling.

*Note: Use clean instruments and avoid the use of lubricants (i.e. WD-40) when sampling to prevent inaccurate results.

  1. Collect a representative sample from areas that best represent the field average. Be sure to sample from areas with similar soil types, topographies and covers. Avoid problem areas that do not accurately represent your soil. We recommend a soil temperature at a minimum of 50° F.

*Example: If a field has three (3) predominate soil types in a ratio of 50%, 30%, and 20%, soil cores should be taken from those sites in similar ratios for a representative sample. This sample example can be used for topography and production.

  1. Using a soil probe, insert the probe at a 90° angle, without twisting, to the desired depth (0-6” or 0-8” are common*). Twist a quarter of a turn then pull straight out. If the soil is clearly compacted more than 1” within the probe, remove the core and sample again. The probe does not need cleaned between sampling, unless the probe is clogged, or the soil is wet.

*Note: All samples must be taken from the same depth for proper interpretation

  1. Combine at least ten (10) cores for the area of interest. Thoroughly mix cores and send a subsample of two (2) cups in a plastic lined paper soil bag or plastic bag (i.e. sandwich bag, whirlpac, etc.)
  1. Clearly label all the sample bags with unique identifiers such as a location or a number. These labels must match the label names used on the submittal form and must indicate the desired test and sampling depth in addition to necessary customer information (i.e. Name, Address, Email, and Phone Number). This form is accessible on our website.

*Hint: Label bags using a Sharpie or pen prior to sampling to prevent labels from smearing.

  1. Store samples in a cool and shaded location for a maximum of two (2) days or in the fridge for a maximum of two (2) weeks prior to shipping. If longer times are expected, store in the freezer.

*Note: Microbial activity can be strongly impacted if not properly stored.

  1. Place all samples and submittal forms in a box and ship samples using a standard carrier. We recommend two (2) to three (3) day shipping.

Soil Health Sampling Instructions (PDF)

The laboratory offers sampling bags, free of charge, to customers at the laboratory. If you would like sampling bags sent to you, please contact the laboratory. Soil samples can be collected using any plastic bag but must be properly labeled. Containers, such as coolers, will not be returned unless previous arrangements have been made with the laboratory.
  1. Soil samples can be collected using a clean probe, spade or shovel. A soil probe allows samples to be taken from an accurate depth. If using a spade or shovel, insert the spade to the desired depth then re-insert the spade next to the first opening to create a slice. Remove the soil slice and make a one (1) inch core strip from the entire slice, removing any plant matter that may be at the top.*
  2. Samples should be taken from the desired depth of the project. Often, surface sample depths of 0 – 8 inches are used to measure nutrients within the root zone, although deeper sub samples can be taken to measure mobile nutrients. These depths may include 8 – 24 inches or greater.
  3. Collect a representative sample from the area and place in a plastic bucket to mix cores. Be sure to sample from areas with similar soil types, topographies and covers. Avoid problem areas that do not accurately represent your soil. If desired, test these areas separately to determine potential soil issues.
  4. Common methods of soil sampling include random composite sampling and grid sampling. Random composite sampling can include selecting sites throughout a field with no organization. A composite sample of ten (10) to fifteen (15) cores combined may represent a 40-acre area. Grid sampling can be a field that has been divided into equal areas and eight (8) to ten (10) cores taken from those areas, mixed and submitted as one sample for that area.
  5. Clearly label all the sample bags with unique identifiers such as a location or a number. These labels must match the label names used on the submittal form and must indicate the desired test in addition to necessary customer information (i.e. Name, Address, Email, and Phone Number). This form is accessible on our website. *Hint: Label bags using a Sharpie or pen prior to sampling to prevent labels from smearing.
  6. Submit the samples to the laboratory as soon as possible.
*Avoid using brass, bronze or galvanized tools and clean sampling tools, as this can cause contaminated samples and incorrect results. Soil Sampling Instructions (PDF)
The laboratory offers sampling bottles, free of charge, to customers at the laboratory. If you would like sampling bottles sent to you, please contact the laboratory. Water samples can be collected using any liquid container, as long as the container has been properly rinsed and contains no contaminates. Containers will not be returned unless previous arrangements have been made with the laboratory.
  1. Select a sampling site free of excess contaminants (i.e. excessive dust, rain, snow or rusted faucets).
  2. Remove any strainers, aerators, purification or hoses that may be connected to the faucet.
  3. Using the cold water faucet, allow the water to thoroughly flush the water lines* (often 2-3 minutes unless testing from a well or lead distribution lines are a concern). A typical indicator of complete flushing is a stabilized water temperature.
  4. Rinse the sampling container in the water a minimum of three (3) times. To collect the sample, fill the sampling container until half an inch of air space is left at the top. Do not allow the bottle to touch the faucet or overfill the container.
  5. Tighten the container cap to prevent loss of the sample. If the sample is being mailed, seal the cap with tape to prevent leakage. Samples do not need to be kept cool if delivered to the laboratory within 24 hours.
  6. Clearly label all the sample bottles with unique identifiers such as a location or a number. These labels must match the label names used on the submittal form and must indicate the desired test in addition to necessary customer information (i.e. Name, Address, Email, and Phone Number). This form is accessible on our website.  *Hint: Label bottles using a Sharpie or pen prior to sampling to prevent labels from smearing.
*If a water source has not been used recently (such as in a vacant home) allow the water to run for 1 hour minimum through an outdoor faucet. This allows the wells to flush and will provide a representative sample. If a well has recently been disinfected (i.e. chlorinated), make sure all traces of chlorine have been flushed from the well prior to sampling. Water Sampling Instructions (PDF)
Plant tissue sampling should represent the crops in your field and should be collected from multiple areas within a field. Do not sample from stressed plants or plants that have signs of chemical or mechanical damage, insect damage or disease or after a rain (or irrigation) event. Plant tissue collection is dependent on plant type and growth stage (See chart below). Samples should be dirt free and placed in a clean paper bag. Do not wash plants or use plastic bags. Samples should be well ventilated and never frozen. Deliver the samples to the laboratory as soon as possible or store the samples in a refrigerator until they can be delivered.
  1. Clearly label all the sample bags with unique identifiers such as a location or a number. These labels must match the label names used on the submittal form and must indicate the desired test in addition to necessary customer information (i.e. Name, Address, Email, and Phone number). This form is available on our website. *Hint: Label bags using a Sharpie or pen prior to sampling to prevent labels from smearing.
Plant Growth Stage Part to Sample No. of Plants
Corn Up to V6 (6 leaf) All above ground portion 20 – 30
Prior to tasseling Top collar leaf 15 – 20
Tasseling to silking Ear leaf 15 – 20
Soybeans Seedling (Less than 12 inch) All above ground portion 20 – 30
Flowering Top fully developed trifoliate leaves 20 – 30
Small Grain Seedling (Less than 12 inch) All above ground portion 50 – 100
Boot to heading Flag leaf 40 – 50
Plant Sampling Instructions (PDF)

Cover crop sampling should represent the cover in your field. One (1) sample represents a forty (40) acre area. Samples should be dirt free and placed in a clean, plastic trash bag. Do not wash plants. Samples should never be frozen. Deliver the samples to the laboratory as soon as possible.

  1. Identify a 3-foot by 3-foot area in the field that best represents the average cover crop coverage.
  2. Remove all above ground plant matter within this area and gently shake to remove excess dirt.

    Note:
    Do not include soil in the sample.
  1. Place sample in a large bag, such as a trash bag, and submit the sample to the laboratory promptly. Sample degradation, such as molding on sample, can cause improper results.
  2. Label the sample bags with unique identifiers such as a location or number. These labels must match the label names used on the submittal form and must indicate the desired test in addition to necessary customer information (i.e. Name, Address, Email and Phone Number). This form is available on our website.

Cover Crop Sampling Instructions (PDF)

Stalk nitrate testing for corn is done late in the season to evaluate the efficiency of nitrogen management during the growing season. Corn stalks can be taken one (1) to three (3) weeks after black layer stage has formed in 80% of the kernels through post-harvest. If sampling after harvest, collect the samples as soon as possible as nitrates can leach from the stalks in the presence of water, such as rainfall.

Samples should be taken from representative stalks in the field. Avoid areas that have been damaged by insects or disease, barren or stalks that have fallen.

  1. One (1) sample should contain ten (10) to fifteen (15) stalks to properly represent an area. Samples should be taken from areas of different management and soil types.
  2. On a standing stalk, remove the stalk six (6) inches above the soil surface. Cut eight (8) inches above the cut and remove all leaves.
  3. Bundle the stalks with duct tape.
    Note:
    Do not use plastic bags to hold the sample. Mold will form and will cause improper results.
  1. Label the duct tape with unique identifiers such as a location or number. These labels must match the label names used on the submittal form and must indicate the desired test in addition to necessary customer information (i.e. Name, Address, Email and Phone Number). This form is available on our website.
  2. Samples should be delivered to the laboratory as soon as possible.

Stalk Nitrate Sampling Instructions (PDF)