KBS026: MCSE: Soil Bulk Density

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Abstract

Sampling Frequency: every three years

Bulk density cores consist of intact cores taken in each plot.

Protocol

Method used for 1988 and 1996 samples

Materials:

  • Root Sampler 7.95 cm dia. (ELKJAMP, Inc., Wageningen, Netherlands)
  • # 5 paper bags (13 X 27 cm) pre-labeled
  • Meter Stick
  • Ruler with metric markings
  • Data Sheets
  • Drying Oven @ 105 degrees C
  • Mettler PJ3600 balance

General Procedure

  1. Pre-label paper bags with the appropriate information about the sample (e.g. date, plot, depth, variate).
  2. Take surface core using root corer 2m south west of station flags 2, 3, and 4.
  3. Measure core height and hole depth ("15 cm.). Place core in paper bag.
  4. Take second core from hole of the first core.
  5. Measure core height and hole depth ("25 cm.) of second core. Place core in paper bag.
  6. If soil moisture is to be calculated, weigh soil cores before drying. Place paper bags containing cores and 10 empty paper bags in drying oven at 105 degrees C for 24 hours.
  7. Remove cores and paper bags from oven and allow to cool for 15 minutes.
  8. Weigh cores and paper bags. Determine soil mass by subtracting mean bag weight from the weight of the soil core + bag weight.

Method used for 1991 samples

  • Bulk density samples were taken using a double cylinder, hammer-driven corer. The outer cylinder absorbs the impact of the hammer and reduces compaction on the sample. The inner cylinder preserves the intact sample for storage and analysis.
  • One sample per plot was taken, 3 m west of the station #3 flag. Two cores were taken at each position. The first core was from the surface to 7.5 cm. The second core was taken after excavation of the hole to 15 cm and represents the 15 to 22.5 cm depth. No core was retained to estimate bulk density from the 7.5 to 15 cm depth. The exact depth of each core was recorded. Any anomalies in the core (gravel, roots, unlevel core surface) were recorded.
  • The inner cylinder containing the 0-7.5 cm core was transferred to a wax-lined cardboard container, stored in a cooler, and sent to Dr. Smucker’s lab for pore distribution analysis. The deeper cores (15 – 22.5 cm) were dried at 120 degrees C until core weight achieved a constant mass. Core weight was recorded. Cores were broken apart and gravel was removed, weighed, and subtracted from soil core weight.
  • Cylinder core volume used in calculations was 347.3 cm3
    .

Method used for 1999 1m samples

Bulk density samples were taken using a 3 inch diameter Giddings probe.

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