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FAB N-min Processing Day 2

Background

We measure nitrogen mineralization to better understand how species diversity and composition will affect nitrogen cycling in the system.

Materials Needed

  • Plastic pipettes
  • Specimen Cups with soil and KCl
  • Scintillation vials
  • Tape
  • Disposal containers for liquid and pipettes
  • Sharpies
  • Computer

Template

Template link of weights needed for calculations

Summary

The following are the end products:

  • Initial

    • Scintillation Vials of Initial insitu extractions (v)
    • Long-term storage bags with soil (l)
    • Scintillation vials of dried soil for total CN
    • Cans of dried soil (c)

  • 30 days later

    • Scintillation vials Final insitu extractions (v)
    • Scintillation vials Controlled Incubation extractions (k)
    • Long-term storage bags with dried soil (l)
    • Cans of dried soil (c)

Detailed methods

Cans

  1. Remove any cans that were dried overnight in the drying oven.

  2. Let the cans cool before replacing the lid on top of the can and weighing. Weighing warm samples will yield poor results.

  3. Open the E141 Weighing database and click “Soil N”. Then click “Dry Can” to open the correct weighing program.

  4. Place the can on top of the scale and scan the barcode. Press enter and repeat this process with all cans.

  5. This process may take more than one day depending on how many trays of cans can fit into the drying oven. Each tray needs to be in the drying oven overnight at 110 degrees Celsius.

Specimen Cups

  1. Very carefully move the trays of “initial” specimen cup from the fridge to the workspace you will be using.

  2. Take a cup and open it. Using a plastic pipetter, pipette out a small amount of liquid from the cup vial and place it in a plastic scintillation vial. Cap the scintillation vial and shake the liquid around. Discard the liquid in a container.

  3. Fill the scintillation vial with liquid from the cup by pipetting from one to the other. Do not fill the vial completely to the top because when we freeze these samples they will break the vials in the freezer if they are full.

  4. Try not to transfer any roots or debris from the specimen cup to the scintallation vial. Try not to bump the cup or cause the soil to become mixed with the KCl again. If the sample becomes cloudy before transferring it, set the cup aside and wait to process it until the soil settles again.

  5. When the vial is almost full put the cap on the vial and discard the plastic pipette. Label the vial with “Initial (v) - Vial”. Use tape if the label will not stick.

  6. Write the plot number on the cap with a sharpie marker.

  7. Repeat this process with all of the samples, including the blanks. Do not pour the blanks into the small vials but make sure to use a pipette.

  8. When all of the samples have been transferred put all of the small vials in order by plot number and label the boxes with the following information; the year, FAB2, “initial” or “final” with “controlled” or “insitu” Nmin sampling, the plot range in the box, the box number.

    1. The blanks should be placed after all of the plots in order as well.

  9. Store samples in the scintillation vials in the freezer until ready to run assay.

Finalize

  1. Ensure all initial and final weights for cans and cups are recorded and saved. Redo any samples that are missing weights.

    1. Reweigh cans if dry weight is greater than wet weight. Most likely scenario is that the cans were weighed when warm. If this is not the case, reweigh a new can to dry overnight.

  2. Ensure all of the following are complete:

    1. Initial
      1. Long-term storage
        1. C/N scintillation vials
      2. Initial vial extractions
      3. Controlled specimen cups for 30-day incubation
      4. Dry cans for soil moisture
    2. Final (30 days later)
      1. Long-term storage
      2. Final insitu vial extractions
      3. Controlled incubation extractions
      4. Dry cans for soil moisture

  3. After all of the samples are accounted for, throw the extracted specimen cups in the dumpster, take the labels off the metal trays, and place the trays and Styrofoam inserts back in the closet.

  4. Double check on step 2. With confidence that all steps are complete, toss soil samples in the “s” labeled ziplock bags out in dumpster or ask Mark Saxhaug if he wants the remaining soil.

Last update: October 20, 2022