Soil Collection and Handling
Timing: Soil can be collected prior to beginning growing season activities, throughout the growing season or after harvest, providing it is done when there is adequate soil moisture and there have not been any recent physical disturbances, additions of soil amendments, or other chemical inputs. Use the same georeferenced locations and sample under similar soil conditions, and if possible, the same time of year in the future to monitor practice effects.
Location: Identify where soil sampling will take place. Collect soil from at least 3 representative locations. At each main location, collect soil from the main location and 4 subsamples around the main location (5 subsamples per/location). Combine all 15 subsamples to create 1 composite sample.
- Avoid collecting or combining soil samples from:
- Wheel tracks or drive lanes, field borders, depressions, or other odd areas within the field
- Areas with historically lower or higher productivity
- Different landscape positions
- Fields with different crops or rotations, or the same crops with a different management
- Row versus inter-row areas
- Eroded versus non-eroded areas
- Saturated Soil
- Collection
- Ensure all equipment is clean and free from residue prior to collection
- Remove vegetation or debris on soil surface
- Use a tile spade or straight shovel and dig a small hole about 8 inches deep
- A soil probe ≥ 1-inch diameter may be used in place of a spade, but it is not a preferred tool.
- Use of probes may interfere with aggregate stability results.
- Take a vertical, rectangular slice of soil from one side of the hole, approx. 2 inches thick and 6 inches deep
- Keep the slice the same width at the top and bottom
- Ensure the sample does not have more soil from the top or bottom of the slice
- If needed, remove any extra soil to ensure an even, rectangular sample.
- Place into a relatively clean bucket
- Repeat the steps for all 14 of the remaining sampling locations
- Thoroughly mix and put 4-5 cups of soil into a one-gallon re-closable freezer bag
- Add an additional 1-2 cups for the comprehensive chemical test
- Consider saving additional soil to archive for future analysis (e.g. new molecular techniques)
- Handling and Shipping: When returning from the field, if samples will not be immediately processed, place them in a refrigerator. Split the sample into appropriate amounts for soil health testing, chemical testing, or archiving.
- Do not freeze or air-dry the soil being sent for soil health and nutrient analyses.
- If archiving, dry the soil and store in a sealed glass container.
- Double bag the soil to ensure against bag breakage during shipping.
- Do NOT put the submission form in the sample bag.
- Ship soil and submission forms in a tightly packed cardboard box using 2- or 3-day service.
- Ship on a day that ensures samples do not arrive on the weekend or a holiday.
