Soil Quality Assessment: Qualitative and Quantitative Methods Susan S. Andrews, Ph.D. Ecology National Leader for Soil Ecology Natural Resources Conservation Service United States Department of Agriculture

Scientists’ Definitions of Soil Quality “fitness for use” - Larson & Pierce, 1991 “capacity of the soil to function” - Karlen et al. 1997

Soil Functions Recognized by USDA-NRCS  Maintaining biodiversity & productivity  Partitioning water and solute flow  Filtering and buffering  Cycling and storing nutrients and energy  Physical support and stability - after Seybold et al., 1997

EU Soil Functions  Crop and forest biomass production  Storing, filtering and transformation of nutrients, substances and water  Support of biodiversity  Provision of physical and cultural environmental for society  Provision of raw materials  Acting as a carbon pool  Protection of geological and archaeological heritage -Thompson, 2006

Components of Functional Stability  Soil Resilience The ability of a soil to recover its previous level of function after a disturbance  Soil Resistance The ability of a soil to resist change in function throughout a disturbance - Pimm, 1984; Seybold et al., 1999; Andrews, 2003

Differences in Resistance and Resilience Soil Function Time (years) Compaction Disturbance Soil with high resistance Soil with low resistance and high resilience -Seybold et al., 1999 Soil with low resistance and low resilience

Soil Function Time A B C Disturbance -Seybold et al., 1999 Two Types of Resilience Level of recovery = (B - C)/(A - C) Rate of recovery = d[(B - C)/(A - C)]/dt

Inherent vs Dynamic Soil Quality  INHERENT  reflects natural characteristics  based on soil forming factors  climate, parent material, topography, and biota, all acting over time – Jenny, 1941  DYNAMIC  describes status or condition of soil  emphasizes soil function  result of land use, management practice, or natural disturbance

Inherent Soil Quality Soil Quality Time Soil A Soil B

Dynamic Soil Quality Soil Quality Time Aggrading Sustaining Degrading Baseline

Soil Quality and Sustainability  Considered an indicator of sustainable land management – Doran and Zeiss, 2000  Change in SQ with time is the primary indicator of sustainable land management – Karlen et al., 1997  “Sustainable agriculture – sustains the people and preserves the land” – Tom Franzen, US Farmer

Soil Quality and Sustainability Soil Quality Air Quality Water Quality Environmental Quality Agricultural Sustainability EnvironmentalQuality EconomicViabilitySocialAcceptability Physical Chemical Biological Soil Quality Components

Soil Quality and Sustainability as Emergent Properties  Sustainability not a system component  Soil function arises from interaction among soil properties and processes  Leading to manipulating management systems rather than individual properties - Carter, Andrews & Drinkwater, 2003

Emergent Properties  Unique phenomena, not predictable from lower levels of organization  Odum, 1984  Systems are ‘greater than the sum of their parts’  Odum, 1953  Rountree, 1977  Stephens and Hess, 1999

Soil Quality Indicators  Functions and emergent properties often cannot be directly measured  Must use integrative indicators to assess soil quality and function  physical indicators  chemical indicators  biological indicators Chemical Physical Biological OM

Soil Quality Indicators  Representative of soil function  Sensitive to management  Easily measured and reproducible  Reliable  Accessible to users  Applicable to field conditions  Integrate soil physical, chemical, and biological properties & processes -Doran and Parkin, 1994 & 1996; Gregorich et al., 1994

Why Use Soil Quality Indices?  Synthesize assessment, monitoring or inventory activities  Organize & prioritize large data sets  Quantitatively evaluate diverse or complex systems - After Andrews, 1998; Kremen, 1996

Uses of SQ Assessment vEducational tool

Uses of SQ Assessment Soil Quality Alt. 1 Alt. 2 v Adaptive management Soil Quality Time Aggrading Sustaining Degrading Baseline v Monitoring

Uses of SQ Assessment  The importance of soil change is its affect on function.  Consequences of change depend on reversibility. (Arnold et al.,1990) Productivity Land degradation Land use impacts  Inventory: Dynamic Soil Properties (DSP) in US Soil Survey Standard methods

Assessment Tool Requirements  practical tools for SQ assessment must be:  accurate  simple to use  meaningful  Site-specific standards & guidelines for interpreting soil quality indicators

Other considerations  Intended users  Who performs test?  Who interprets test?  For what purpose?  Time scale  Spatial scale of interest

Tool Development Approach Tool Development Approach user input user input research based issue driven Sustainable Decision- Making

Focus Groups

Common themes for desired soil quality information Common themes for desired soil quality information  site-specific interpretations for indicators  ability to make soil quality comparisons over time, including changes in carbon  predictions of management practice effects on soil quality “If I switched to no-till, what outcomes can I expect?“ –IL-IA farmer “If I switched to no-till, what outcomes can I expect?“ –IL-IA farmer

Soil Quality Cards and Design Guide  On-farm qualitative indicators  How to develop soil quality cards with local farmers  Consensus building techniques

Example Descriptive Indicators  Crusting or surface sealing  Rills, gullies, or ripple marks  Sand dunes  Salt crusts  Leaf color  Standing or ponded water  Loose, soft, crumbly, loamy, earthy smelling, massive, lumpy, dense, etc...

Field Test Kits

SQ Test Kit Uses in the US  Education  NRCS  Crop advisement  Private farm consultants (primary target audience)  Occasional studies  NRCS-university partnerships Liebig and Doran (1999) successfully compared the SQ Test Kit tests with its laboratory analogs.

Predictive Indices  Soil Conditioning Index (SCI)  Trend in soil carbon Improving Degrading Sustaining SCI Carbon (lbs)

The Soil Conditioning Index =(OM x 0.4) + (FO x 0.4) + (ER x 0.2)  OM accounts for organic material additions; ƒ(biomass produced, decomposition)  FO represents physical disturbance from field operations  ER is the estimated loss of soil material by sheet, rill, irrigation and/or wind erosion Where:

Regression of SCI Outcomes and Measured Carbon Change -Norfleet, unpub.

Practice-based Indices:  Used in the US for farm bill conservation programs since 2006  EU considering practice-based approaches Soil and Water Evaluation Tool (SWET)

Soil Quality in the Soil & Water Evaluation Tool (SWET)  Questions organized by Disturbance Type  Physical, biological and chemical  5 Ecosystem Services  C sequestration  Nutrient cycling  Physical stability  Habitat for soil biota  Water partitioning (and salinity management)  Proportional Weighting factors

Selected Means, Tillage Studies IA Tillage CA Tillage & Cover Crops

Test-based Indices  Cornell Soil Health Assessment  Soil Management Assessment Framework

Cornell Soil Health Assessment  Developed with farm soils in New York, USA  Interpretation using scoring curves (after Andrews et al., 2004) (after Andrews et al., 2004)  Targeting Crop Advisors  Used in NY State NRCS for US Farm Bill conservation programs -van Es, pers. comm., 2006

The Soil Management Assessment Framework  Tool to assess the effects of management on soil function  Based on indicator measurement  USDA-ARS collaboration to standardize methods  Validated at four sites, used worldwide  Site-specific framework transferable across soils, climate, and management practices

Three Step Approach score 2. Interpretation 1. Indicator Selection Minimum Data Set Indicator Index Value 3. Integration - Andrews et al., 2004

Step 1. Indicator Selection  The concept of soil quality is goal dependent  Management goals for soil use dictate which functions are important  Relationship to functions and comparison type determine what indicators to use

Step 2. Interpretation Soil A Soil B Soil Function Inherent SQ Dynamic SQ 50% 85% Dynamic SQ with respect to Inherent capability

Multi-function, Factor-based Interpretation

Scoring Algorithms

Site-Specific Interpretation Factors Site Specific Factors

Observed Scored Management System Individual Indicator Interpretation Scored shows No Differences: SAR (SAFS CA dataset) Org Low Conv-4 Conv-2 Observed SAR Scored SAR a ab bc c a aa a

Step 3. Integration into SQ Index Nov 95 Nov 96 May 97 Nov 97 May 98 *** denotes significance at Index Value BIFS Farm 2 -Andrews et al., 2002 Sampling Date

Summary  Soil Quality is the capacity of soil to perform the functions necessary for its intended use  Understanding of soil resistance and resilience is important for appropriate conservation management  Soil quality is a component of sustainable agriculture  There are multiple uses of soil quality assessment tools  There are multiple types of assessment tools; the choice of which to use, depends on your needs

Get your facts first, and then you can distort them as much as you please - Mark Twain