70th SWCS International Annual Conference July 26-29, 2015 Greensboro, NC

1. The Science of Soil Health and
Value of Soil Stewardship
Francisco J. Arriaga, PhD
Soil Management State Specialist
Dept. of Soil Science & UW-Extension
Francisco.arriaga@wisc.edu
608-263-3913
SWCS Conference, Greensboro NC
July 28, 2015

2. What is Soil Health?
• “The capacity of a soil to function within
ecosystem boundaries to sustain biological
productivity, maintain environmental quality, and
promote plant and animal health.”
(Doran and Parkin, 1994)
• Abbreviated version: Ability of a soil to function
in a way that benefits both humans and the
environment.
[Note this assumes there is a baseline (i.e.
maximum potential) for different soils]

3. Soil Health Indicators
(or Soil Properties that Influence Productivity)
Physical Chemical
Biological
•density
•infiltration
•water retention
•aggregation
•nutrient availability
•pH
•CEC
•organic matter
•biological activity
•roots
•organisms
Soil Health

4. Proposed Basic Soil Health Indicators
(Doran and Parkin, 1994)

5. Soil Quality Indicators & Their Impact
Measurement Process Affected
Organic matter Nutrient cycling, pesticide and water retention, soil structure
Infiltration
Runoff and leaching potential, plant water use efficiency,
erosion potential
Aggregation Soil structure, erosion resistance, crop emergence, infiltration
pH Nutrient availability, pesticide absorption and mobility
Microbial biomass
Biological activity, nutrient cycling, capacity to degrade
pesticides
Forms of N
Availability to plants, leaching potential, mineralization and
immobilization rates
Bulk density Root penetration, water/air filled pores, biological activity
Topsoil depth Rooting volume, water and nutrient availability
Available nutrients Capacity to support plant growth, environmental hazard
(Karlen et al. SSSAJ , 1997)

6. (Lado, Paz and Ben-Hur, 2004)

7. Aggregate Formation/Stability Concept
(Six et al. SSSAJ, 1999)
Energy in the organic
matter “wasted” to
re-form aggregates

8. Assessing Soil Health
1. QUALITATIVE:
– Soil Health?
– Smell, feel, look, taste?
– Soil Quality Rating
2. QUANTITATIVE:
– Chemical
• pH, O.M., nutrients
– Physical
• Structure, bulk density
– Biological
• Respiration, microbial
biomass
– Integrate factors into an index

9. Soil Health Score Card Example
soil test showed need
for potassium
1. add potassium fertilizer
2. ?????

10. Soil Health Score Card Example (cont.)
wheat
2013somewhere in Wisconsin
Sept 25, 2014 X
X
X
X
X
X
X
X
X
not applicable
cover crop planted; slightly denser soil layer detected between 6-8” of depth.

11. Field Based Assessments (Visual)
photos: Roger Schmidt, NPM Program

12. Quantitative Assessments
• Often require for soil samples be taken and sent to a
laboratory
• Attempt to measure chemical, biological and physical
properties
• A score is given to the soil based on the properties
measured

13. Proposed Basic Soil Health Indicators
(Doran and Parkin, 1994)

14. Biological Indicators
(Moebius-Clune et al.,2008 )
OM- Soil organic matter PMN – Potentially mineralizable N
NemParasitic – Parasitic nematodes EEG – Easily extractable glomalin conc.
NemBeneficial – Parasitic nematodes TG – Total glomalin concentration
Decomp – Cellulose decomposition rate
Continuous Corn System with Residue Harvest (32 years)
• Most sensitive indicators were: Db, AWC, OM, Decomp and TG
• Tillage had a lager positive impact on improving indicators than
returning corn residue to soil

15. 0
500
1000
1500
2000
2500
0 10 20 30 40 50 60 70 80
Time Since Plowing (days)
CumulativeCO2(kgC/ha)
Moldboard No Till
Microbial Respiration
Plowed July 23, 1997
(Rochette and Angers, 1999)
Time (days)

16. Property SH Assessment SH Rank State Based
State Based
Recom.
pH 6.5 ok 7.3 ok
Phosphorus (ppm) 6.7 ok 34 High (ok)
Potassium (ppm) 153.9 ok 90 Very low/low (ADD)
OM (%) 3.4 ok 4.2
Score YES NO, but gives nutrient
recommendations
based on field trials
(CALIBRATION WITH
CROP RESPONSE)
The Potential Issue with Some SH Assessments

17. The “New” Frontier
• Microbiological assessments (e.g.
metagenomics)
• Linking soil quality indicators to crop
performance
• New statistical approaches to develop a robust
SH/SQ Index

18. (Stine & Weil, 2002)
Tillage:
conventional
reduced
no-till
Corn Yield &
Soil Health
Indicators

19. The “New” Frontier
• Microbiological assessments (e.g.
metagenomics)
• Linking soil quality indicators to crop
performance; new statistical approaches
(Dorr de Quadros et al., 2012)

20. Closing Remarks
• The science of SH/SQ assessment has been moving slowly
from qualitative to quantitative, as new knowledge is
developed by scientists and implemented by practitioners.
• Care should be taken not to “over sell” a specific SH metric or
procedure, as this can turn the end-user away.
• Microbial community composition and function assessments,
and linking soil indicators to crop and environmental
performance is the current focus and next “frontier”.

21. Photo: F. Arriaga, 2012 Workshop Brown Co. Land & Water Conservation
Soil Management Matters
E-mail: francisco.arriaga@wisc.edu
Phone: 608-263-3913