Protocols

KBS004: Soil Sampling

In use from 1989-04-01

Abstract

Sampling Frequency: minimum of once per month through the growing season (April -October)

Composite soil samples consist of 1-inch composited cores per plot taken to soil depth at each of the 5 baseline sampling stations per plot . At each sampling station, cores are taken perpendicular to the crop row and between rows . Soil cores from poplar plots are taken on a diagonal transect between two trees . In successional plots cores are taken at 7.5" intervals from an arbitrary starting point . No soil cores are taken across wheel-track rows in any plots . Soil cores from each plot are sieved and mixed into one soil composite sample .

Protocol

Soil cores are taken at 5 sampling stations per plot. Soil cores (2.5
cm dia.) are taken north of each station flag to a depth of 25 cm. An
equal number of cores are taken within row and between row when row
crops are grown. In non-cropped systems, cores are taken at 10 cm
intervals. All cores from each plot are composited in one sampling
bag. A standard sampling consists of 2 cores at each station. Some
samplings will have more cores when soil demand is high. Normally
samplers start at the south end of Rep 1, 2, 3, and 4. They work north
and finish on the north side of Rep 5. Rep 6 and treatment 8’s
are sampled after finishing with rep 5. 5. Forested sites are
collected by one person at the same time the main site is being
sampled. If 5 people are not available the forested sites maybe
sampled in the afternoon while soil from the main site is being
sieved.

The soil is brought to the lab and sieved through a 4 mm screen to
remove debris and to homogenize the soil sample. Each treatment has a
specific screen in order to reduce contamination between
treatments. Latex gloves are worn when sieving and mixing the
soil.

Field moist sieved soil subsamples are distributed to individuals
requesting soil prior to sampling. Excess soil is air dried and stored
by date of sampling. All samples, except the April sample, are
disposed of at the end of the year. The April sample is archived for
CN analysis.

Mineralization potential may be assessed by as the difference in
nitrate and ammonia values from the initial sampling and an
"incubated" sample. Incubations are perfomed on a subsample
of the initial composite sample which is placed into a gas-permeable
plastic bag and buried in the plot from which the soil
originated. Incubation length is 21 days. (see Short-term
mineralization file for details).

Materials

  1. Avery 5160 Laser Labels
  2. 8×4×18 Plastic sampling bags (drawer F7)
  3. Sharpies
  4. Butter knives
  5. Site maps
  6. Soil probes
  7. Buckets
  8. Latex gloves
  9. Tote Trays
  10. Brush
  11. 4 mm mesh soil sieves

Procedure

  1. Label plastic bags with appropriate information about the
    sample (e.g. project, date, plot, variate. Cover labels with clear
    mailing tape to secure label to bag and to protect against
    moisture.
  2. Prepare sampling buckets. Each bucket should have the
    following: site map, sharpie marker, butter knife, sampling bags,
    and soil probe.
  3. Take samples to 25 cm at each of the 5 sampling stations. A
    butter knife is helpful in removing soil from the probe. In cropped
    systems, an equal number of cores should be taken in the crop row
    and between the crop row. Take the same number of cores from
    non-cropped systems. Composite all samples for each plot in one
    plastic bag.
  4. Tie the sample bag and place in the alleyway to be picked up
    when the sampling is completed. All efforts should be made to
    complete sampling in all plots on the same day.
  5. Take a core at the edge of the next plot to clean the soil
    probe. This will reduce contamination between plots.
  6. Pick up soil samples and return to dry lab.
  7. Separate soils by treatment.
  8. Wear latex gloves while sieving. Sieve each soil sample using
    the 4 mm mesh soil sieve labeled for that treatment. Sieves are kept
    in the dry lab.
  9. Sieve soil into a plastic tote tray. Return sieved soil to the
    plastic sample bag. Discard rocks and large organic matter remaining
    on the screen.
  10. Brush sieve and tote tray clean.
  11. Change latex gloves after each treatment.
  12. Weigh plastic bags containing sieved soil and record weights in
    lab book.
  13. Place soil samples into 4 degrees C
    refrigerator

Author: Tim Bergsma

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