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Soil Aggregate Stability in Rangelands

Soil Aggregate Stability in Rangelands. Leonard Cratic Mentor: Jeff Stone USDA-ARS SWRC U NIVERSITY OF. Introduction. Erosion is a process which impacts the sustainability of rangelands. There is a need to develop simple tools to evaluate sustainability of rangelands.

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Soil Aggregate Stability in Rangelands

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  1. Soil Aggregate Stability in Rangelands Leonard Cratic Mentor: Jeff Stone USDA-ARS SWRC UNIVERSITY OF

  2. Introduction Erosion is a process which impacts the sustainability of rangelands. There is a need to develop simple tools to evaluate sustainability of rangelands.

  3. Problem Statement Two methods being used to estimate runoff ratio and erosion: Direct measurement • Rainfall simulation • Expensive and time consuming Indirect measurement • Slake testing • Measures soil aggregate stability • Quick and inexpensive

  4. Objectives Assess the influence of plant cover on soil slake. Determine whether correlations exist between soil slake and runoff and erosion.

  5. Methods Rainfall simulation • Rainfall is applied to a 2x6 meter plot and runoff and erosion is measured. • Four plots per site

  6. Soil Aggregate Stability Measures how well a soil ped retains its structure in water • Soil stability kit • 18 samples per plot • Presence of plants noted and soil samples ranked 1-6 (unstable-stable)

  7. Study Areas Loamy Uplands ecological site • Soil-vegetation association • 5 sites evaluated in Southeastern Arizona • From observations • ER2 and KREE are most stable • ER4G and ER4S are moderately stable • ER3 is least stable

  8. Analysis Slake evaluated using a t-test • Under and outside canopy • Among study sites Regression analysis (slake vs. rainfall simulation) • Slake vs. runoff ratio • Runoff ratio = runoff / precip. • Slake vs. sediment yield • Sediment yield = sy / precip. / slope

  9. Under vs. Outside Canopy Means are significantly different if letters are different

  10. Slake Among Sites Means are significantly different if letters are different

  11. Slake vs. Runoff

  12. Slake vs. Sediment Yield

  13. Conclusions • Soil that was protected by canopy cover had more stable aggregates. • Significant differences in slake were between ER4S, ER2 and KREE. • No correlation was found between slake and runoff ratio. • A negative correlation was found between slake and sediment yield. • The addition of more data will help to strengthen the validity of using slake testing for erosion assessment.

  14. Acknowledgements Susan Brew Jeff Stone Chandra Holifield Collins Rae Gomez-Pond Jared Buono Jonathan Krattickk Jakucki

  15. Thank You

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