Soil aggregate stability in rangelands
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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

Soil Aggregate Stability in Rangelands

Leonard Cratic

Mentor: Jeff Stone

USDA-ARS SWRC

UNIVERSITY OF


Introduction
Introduction

Erosion is a process which impacts the sustainability of rangelands.

There is a need to develop simple tools to evaluate sustainability of rangelands.


Problem statement
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


Objectives
Objectives

Assess the influence of plant cover on soil slake.

Determine whether correlations exist between soil slake and runoff and erosion.


Methods
Methods

Rainfall simulation

  • Rainfall is applied to a 2x6 meter plot and runoff and erosion is measured.

  • Four plots per site


Soil aggregate stability
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)


Study areas
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


  • Analysis
    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


    Under vs outside canopy
    Under vs. Outside Canopy

    Means are significantly different if letters are different


    Slake among sites
    Slake Among Sites

    Means are significantly different if letters are different




    Conclusions
    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.


    Acknowledgements
    Acknowledgements

    Susan Brew

    Jeff Stone

    Chandra Holifield Collins

    Rae Gomez-Pond

    Jared Buono

    Jonathan Krattickk Jakucki



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