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FAB N-min Processing Day 1

Background

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

Note: This can be split into 2-3 days especially if not enough help is available.

Materials Needed

Day 1

  • Baskets
  • Plastic spoons
  • Initial specimen cups (v)
  • Controlled specimen cups (k)
  • Cans (c)
  • Sampling bags (s)
  • Long-term storage bags (l)

Summary

The following are the end products of day 1:

  • Weights

    • Initial specimen cups with soil (v)
    • Controlled specimen cups with soil (k)
    • Cans with soil (c)

  • Status of each item

    • Initial specimen cups (v) with soil and added KCL, shaken and sit overnight in fridge for 24 hours until extraction.
    • Controlled specimen cups (k) with soil placed in cardboard box, stored in shade at room temperature for 30 days until KCl extraction.
    • Cans with soil (c) sit in oven overnight for 24 hours until weighing for dry mass.
    • Long-term storage bags (l) with soil, leave open to air dry.

Detailed methods

  1. There are three types of positions (Note: if there are not enough people for each position combine the roles of the lunch person and scooper):

    1. Lunch person
    2. Scooper
    3. Grouper

  2. Soil bags (s) should be stored in refrigerator if not in process.

  3. Lunch person:

    1. Place a spoon, a soil bag, two empty, pre-weighed specimen cups (v and k), the can (c), and empty quart ziplock bag labeled “long-term storage (l)” with the same plot number as the soil bag (s) in a basket and pass the basket to the scooper. The “lunch person” repeats this step.
    2. After every 25 soil samples the “lunch person” should add a blank sample. This requires placing a soil bag labeled “blank”, two specimen cups (v and k) labeled “blank”, and a can (c) labeled “blank” in a basket and passing it to the scooper. No spoon is needed.

  4. Scooper:

    1. Knead the soil bag to mix the soil and to break up any soil clumps in the bag. This should last approximately 30 seconds.
    2. The scooper takes two heaping spoonfuls of soil and places them in the can. Try not to scoop up too many roots or other debris. Then close the lid on the can.
    3. The scooper places two slightly heaping spoonfuls of soil into the “initial” and “controlled incubation” vials. Again, try not to scoop up too many roots or other debris. Close the lid and make sure that it is on tightly and correctly.
    4. Scoop approximately 100 grams of soil into the “long-term storage (l)” quart size ziplock bag. Do not need to weigh. Get an approximation of what the weight looks and feels like in the bag and eyeball the amount each time.
    5. If the scooper receives a blank sample just open the vial for 30 seconds to simulate what occurs with an actual sample. Then close the lid tightly and send the sample to the grouper.

  5. Grouper:

    1. Open the E141 weigh database and click on “Soil N” then click on “Group Weights” to open the correct program.
    2. Scan the soil bag (s) first.
    3. Place the “initial” specimen cup (v) on the scale and scan the cup. When taking the cup off make sure to check that the cap is on tightly before placing it in a tray.
    4. Place the can on the scale and scan it. If the plots do not match the program will not allow you to move on.
    5. Weigh the “controlled incubation (k)” vial and record in excel.

  6. Proceed to step 7 when all samples are processed and weighed.

  7. Initial Specimen Cups (v)

    1. Add 1.0 M KCl solution
      1. Make up a 1.0 M KCl solution. Weigh out 745.5g of KCl in a weigh container.
      2. Add 10L of deionized water (accurate to the nearest 10ml) to a clean carboy appropriated for KCL. This will fill 200 50mL specimen cups.
        1. If a different amount is needed, there are 74.55 grams of KCl per mole. Multiply this number by the number of desired liters of water.
      3. Add the KCl to the DI water in the carboy and shake vigorously until dissolved.
      4. Fill the vials with 50ml of KCl using the autopipetter. Make sure that the autopipetter is marked correctly so that it dispenses 50ml of liquid.
      5. When pulling the autopipetter top up to add liquid to the autopipetter, a small amount of KCl is dispensed. Put this in the initial specimen cups with soil (v). Then push down on the autopipetter to dispense the rest of the KCl into the same vial.
    2. Each tray of “initial” cups (v) needs to be shaken in the shaker for 30 minutes on the lowest speed. After the trays are done shaking, they can be placed in the fridge overnight to allow soil to settle.

  8. Controlled Incubation Specimen Cups (k)

    1. Stack “controlled incubation” cups (k) in a cardboard box. Close the box and label controlled incubation and store in the office below the desk (needs to be out of sunlight and a controlled room temperature). Mark the date that this is set at room temperature and let sit for 30 days.
      1. After 30-day incubation, add 50mL of 1.0 M KCl and proceed with step 7b and then “Specimen Cups” steps in Processing day 2 protocol.
        1. Please note: if these samples, cannot be processed immediately, please store in fridge before adding KCl.

  9. Cans

    1. The lids of the cans should be opened and the trays should be placed in the drying oven or the drying room overnight. Make sure the drying oven is set for 110 degrees Celsius.
      1. If oven is unavailable, temporarily store the cans in the drying room until oven is available.

  10. Long-term storage soil bags

    1. Open the bags and air out to dry for several days. Make sure the bags are left wide open (without spilling) for drying.

  11. CN Scintillation vial (can be completed at a later date, not time sensitive):

    1. Label scintillation vial with the appropriate plot number with the CN label. Fill ¾ with the soil in the long-term storage bags. Do not cap until soil is completely dry.
    2. When dry, add 3 3/8 inch and 1-1/4 inch slingshot ammos in the scintillation vial. Fully cover label with clear packing tape and add o-ring around bottom neck of vial and cap.
    3. Proceed to this protocol for grinding and using the Elemental Analyzer.
Last update: October 20, 2022