soil bulk density, total pore space, and compaction due to human foot traffic jessie meeks and ali...

Download Soil Bulk Density, Total Pore Space, and Compaction Due to Human Foot Traffic Jessie Meeks and Ali Theuer, 2001

Post on 24-Jan-2016

213 views

Category:

Documents

0 download

Embed Size (px)

TRANSCRIPT

  • Soil Bulk Density, Total Pore Space, and CompactionDue to Human Foot TrafficJessie Meeks and Ali Theuer, 2001

  • Contents:Purpose and ObjectivesSitesMethodsDataDiscussionWrapping up

  • We explored the relationship between calculated soil bulk density (g/cc) and estimated amounts of human foot traffic.

    Soil compaction increases bulk density and decreases pore space.A decrease in pore space leads to increased erosion and decreased soil productivity.Logging trucks are a known hazard, what can feet do?

  • Site 1: located on the Brook Trail, visited by less than 1,000 people annually (thats 2,000 feet every year)Site 2: located along the river trail, visited by just over a thousand people annuallySite 1Site 2

  • Site 3: located along the main loop trail, over 10,000 visitors per yearSite 4: located along aside trail with about 10,000 visitors per year

  • What did we do?

  • Soil samples were obtained by hammering a can of known volume into the ground, both on and off trail at all four sites.We took keen and meticulous notes and observations.

  • Samples were taken back to the lab and weighed.

  • The shape of some of the cans was compromised while hammering them into the soil.

    The new volume of each can was determined using a graduated cylinder.

  • What did we find?

  • Bulk Density Data

    Chart1

    1.41.037

    1.9361.47

    1.3671.132

    1.7641.132

    on

    off

    Site

    Bulk Density (g/cm3)

    Figure 3: Bulk Density On and Off Trail

    Sheet1

    Appendix B: Calculations Sites 1-4

    Site 1Site 2Site 3Site 4Averages1234

    bulk density=hydrated weight(g)/volume(cm3)on trail BD265.92g/190.00cm3=1.400g/cm3677.71g/350.00cm3=1.936g/cm3218.75g/160.00cm3=1.367g/cm3881.85g/500.00cm3=1.764g/cm31.617g/cm3on1.4001.9361.3671.764

    off trail BD549.42g/530.00cm3=1.037g/cm3676.35g/460.00cm3=1.470g/cm3645.01g/570.00cm3=1.132g/cm3622.41g/550.00cm3=1.132g/cm31.193g/cm3off1.0371.4701.1321.132

    difference.363g/cm3.466g/cm3.235g/cm3.632g/cm3.424g/cm3

    % difference25.93%24.07%17.19%35.83%25.76%

    Sheet2

    Sheet3

  • Chart1

    1.41.037

    1.9361.47

    1.3671.132

    1.7641.132

    on

    off

    Site

    Bulk Density (g/cm3)

    Bulk Density On and Off Trail

    Sheet1

    Appendix B: Calculations Sites 1-4

    Site 1Site 2Site 3Site 4Averages1234

    bulk density=hydrated weight(g)/volume(cm3)on trail BD265.92g/190.00cm3=1.400g/cm3677.71g/350.00cm3=1.936g/cm3218.75g/160.00cm3=1.367g/cm3881.85g/500.00cm3=1.764g/cm31.617g/cm3on1.4001.9361.3671.764

    off trail BD549.42g/530.00cm3=1.037g/cm3676.35g/460.00cm3=1.470g/cm3645.01g/570.00cm3=1.132g/cm3622.41g/550.00cm3=1.132g/cm31.193g/cm3off1.0371.4701.1321.132

    difference.363g/cm3.466g/cm3.235g/cm3.632g/cm3.424g/cm3

    % difference25.93%24.07%17.19%35.83%25.76%

    Sheet2

    Sheet3

  • What does it mean?

  • An average difference in bulk densities of 25.76% between on trail and off trail was calculated As bulk density increases, pore space decreasesBulk density was greater on trail than off trail, therefore pore space is less on trailSoil bulk density reaches a maximum, leveling off (i.e most of the pore space is compacted)Less pore space results in increased soil erosion and decreased soil productivityRelationships among the number of hammer blows, crumpling of cans, and the calculated bulk density were observed

  • SummaryHigher bulk densities on trails suggest that their soils areless productive and more susceptible to erosion than their offtrail counterpartsError: a loss of soil mass may have ensued in the Transporting of samples from container to containerStudy Improvements: continue the study over several years, varying the levels of foot traffic at the sample locations,and tracking the bulk density and total pore space over time.

  • Thanks!