Bio Testing/PLFA Sampling

Sampling for biological testing is slightly different than regular soil testing. It is very important to treat all the samples equally. Listed here are general guidelines to sample for biological testing:

  1. Collect all of your samples for comparison on the same day if possible. Samples may be collected on different days but try to keep sampling events to one week or less if comparisons are to be made between the samples. This reduces changes that may take place if moisture or temperature fluctuates between sampling times.
  2. Use a standard soil core sampler. DO NOT use any form of lubricants on the soil core sampler.
  3. Take 10-15 cores roughly 0-8 inches deep next to the plants or near the rooting structures. You may also choose the same depth that is normally used for a topsoil sample as long as it is consistent.
  4. Combine all the cores, preferably in a zip lock freezer bag or plastic-lined paper soil bag. DO NOT use cloth bags for submitting samples.
  5. Add all sample identification information you need to the sample bag and place in a cooler (A Styrofoam cooler with a lid works fine) or a regular box if shipment times are relatively quick.
  6. Mark each sample and the shipping container BIOTESTING or PLFA to ensure proper handling on our end.
  7. We would like samples to remain near original soil temperature if left unfrozen. Ice packs can be used if sampling during hot weather. Remember to treat all samples equally for individual sampling periods.
  8. Samples may be frozen in a standard freezer for storage prior to shipment. This is especially useful and should be done if samples are being taken at different times.
  9. Samples can be mailed to or dropped off at Ward Laboratories Inc, 4007 Cherry Avenue, Kearney, NE 68848. When mailing samples it is best to send them overnight in a cooler if not previously frozen. However, samples can be sent frozen in a cooler by regular mail in mild or cold weather.

Additional information will be added to the website as new information becomes available. Any questions regarding biological testing may be directed to Lance Gunderson at