Ponath Soil Biology Lab

Biological assessments of soil & compost

Sample Collection Information

Important: Please make sure to follow the Shipping Instructions and send your samples the day of collection to get the most accurate results.

How many samples are needed?

Liquids

For compost tea or compost extract, one sample is needed per liquid.

Solid materials

For solid material, for each of the areas to be assessed, a representative sample of the area needs to be created in a small plastic bag. This representative sample consists of multiple smaller samples (cores or teaspoons) taken from the same area.

Compost

One representative sample (bag) is needed per pile or windrow.

Soil

For soil, one representative sample (bag) is needed per area -- unless several of the areas have the same conditions in which case at least 40% of those areas (randomly chosen) should be sampled.

An area is defined by having the same conditions. Differences in large-enough parts of a plot in any of the following conditions should be considered separate areas:

  • Prominent geographic features (streams, ridges, depressions) and environmental conditions (e.g. flooding, land use)

  • Farming / gardening practices

  • Plant health and productivity

  • Weed pressure

  • Plant cover

  • Existing kinds of plants

  • Kinds of plants intended to be grown

If the land to be assessed has multiple different such areas -- for instance, areas with healthy plants and areas with sick plants, or areas with ridges and areas with depressions -- it is best to draw a map of the land to clearly identify the different areas. If several of these areas have the same conditions (e.g. several weedy areas with same conditions), at least 40% of the areas of this type need to be sampled.

For larger fields with uniform conditions (such as bare soil), one representative sample (bag) is needed per acre.

Questions? Unique situation? Need help?

We are happy to advise ow many samples are needed for your specific situation.

We also offer site visits and sample collection.

Please contact us. We are happy to help.

How to collect samples?

Compost

  1. Take one teaspoon full from at least 5 different locations and depths of the pile (20 different locations and depths for large windrows) and mix in a sandwich-size plastic bag.

  2. Make sure to fill the bag no more than half way. If the bag gets fuller than that, thoroughly combine and mix the sample in a separate sterile container and place a smaller amount into the plastic bag.

  3. Do not expel the air but seal the bag with air left inside to keep the microorganisms alive.

  4. Clearly label with the name of the sample and current date on the outside of the bag using a permanent marker or affixed label.

Compost tea & extract

  1. Pour the liquid into a clean, non-breakable 4 to 8 oz container with a sealable opening (e.g. plastic water bottle with screw cap).

  2. Fill the container â…“ full with the liquid. Leave the remainder of the container empty for air exchange.

  3. Once the screw cap is tightly sealed, cover it with duct tape and place it in a sealed plastic bag.

  4. Clearly label with the name of the sample and current date on the outside using a permanent marker or an affixed label.

Soil

  1. Clear away any loose material on the surface of the soil where you are going to pull a core.

  2. Use an apple corer or similar tool to take a 2-3 inch core from the top 3 inches of soil.

  3. Gently shake the core into a resealable, sandwich-size plastic bag.

  4. Make sure to fill the bag no more than half way. If the bag gets fuller than that, thoroughly combine and mix the sample in a separate sterile container and place a smaller amount into the plastic bag.

  5. Do not expel the air but seal the bag with air left inside to keep the microorganisms alive.

  6. Clearly label with the name of the sample and current date on the outside of the bag using a permanent marker or affixed label.

Single plant

To assess the soil in the root zone of a particular plant, take a minimum of 3 cores from around the plant halfway between the stem/trunk and the dripline.

Group of plants

For a group of plants of the same kind in a small area, take a minimum of 3 cores from the group of plants halfway between the stem/trunk and the dripline.

Larger area of varying conditions

For a field or plot (pasture, garden, lawn, etc.) of varying conditions -- as defined in the "How many samples are needed" section above -- draw a map of the different areas and label each area on the map. Take a minimum of 3 cores from randomly selected locations in each area making sure the locations are well distributed and representative of the area. Take samples like this from at least 40% of the areas with the same conditions and selected at random to get a representative set of areas of the same kind. Use a separate bag for each area. Make sure to label each bag with the label of the area on the map, as this information may be useful later, particularly if you get some unexpected results.

Field of bare soil

For a field of bare soil, take 3-4 cores from 5-6 randomly selected locations per acre making sure the locations are well distributed and representative of the whole field (e.g. do not collect right from the edge of the field). Use a separate bag for each acre. Make sure to mark the areas you are sampling on a map and label the bag accordingly, as this information may be useful later, particularly if you get some unexpected results.

Questions? Unique situation? Need help?

We are happy to advise how to best collect samples for your specific situation.

We also offer site visits and sample collection.

Please contact us. We are happy to help.

Shipping Instructions (Important!)

  1. Prior to collecting and sending the sample(s), make sure to contact us via email or phone/text to schedule your soil/compost assessment and confirm the soil/compost is from inside the Puget Lowland bioregion (Puget Sound region, west of the Cascades). We do not accept soil or compost samples from outside the bioregion.

  2. Print and include the completed Order Form in the package containing your samples.

  3. Please ensure that each plastic bag is clearly labeled (using a permanent marker or affixed label on the outside of the bag) with a sample name that matches a sample name on the Order Form.

  4. Please ensure each bag / bottle with sample material is less than half full and has air inside to keep conditions aerobic.

  5. Ideally, please package your sample(s) in a small box or padded envelope to protect it from impact, which may break the seal of the bag, resulting in compaction of the sample.

  6. Make sure to ship your sample(s) the day of collection. During cooler months, a 2-3 day arrival window is sufficient for mailing solid samples. For warmer months and for liquid samples, we recommend next day delivery. Generally, the sooner a sample arrives, the more accurate the assessment results will be.

  7. You may decide which carrier to use to mail in your sample(s). For reference, please find shipping rates of the following popular carriers:

Please do not hesitate to contact us if you have additional questions with regards to the process of collecting and/or packaging the sample.