1. 2013 Soil Health Workshop
Kerry Clark Bradford Research Center, University of Missouri

2. Purpose of workshop is to provide background and resource material on soil health
Soil biology
Rhizosphere interactions
Soil, landscape and watershed features and interactions
Soil erosion
Improvement through management practices

3. Provide information on methods of soil health assessment
Present soil health research and results that are occurring in Missouri
Forest soils
Agricultural soils
Provide information on methods of soil health assessment
MU Soil Health Lab
Field assessments
Farmer self-assessments

4. Provide material and information for developing soil health presentations and demonstrations for producers
Water infiltration
Water Quality
Soil quality indicator tests
Active carbon
Bulk density
Aggregate stability

5. SOIL QUALITY DEFINITION
Soil quality is the capacity of a specific kind of soil to function within natural or managed ecosystem boundaries, to sustain plant and animal productivity, maintain or enhance water and air quality, and support human health and habitation.
(Karlen et al., 1997)

6. Soil quality has three main components
Sustained biological productivity
Environmental quality
Plant and animal health

7. Soil quality deals with both inherent and dynamic soil features.
Inherent soil quality relates to the natural characteristics of the soil, such as its texture. These qualities are the result of soil-forming factors and processes and cannot be changed easily.
Dynamic soil quality components -- such as organic matter, soil structure, infiltration rate, bulk density, and water and nutrient holding capacity -- are readily affected by management practices. The dynamic component is of most interest to growers because good management allows the soil to come to its full potential.
Inherent and dynamic soil quality components interact with each other. Some soils are much more susceptible to degradation and unforgiving of poor management than others.

8. Soil quality is the integration of biological with chemical and physical measures of soil quality that affect farmers' profits and the environment.
This definition reflects the living and dynamic nature of soil

9. Does Soil Quality = Soil Health ?????
In USA, SSSA Ad Hoc Committee on Soil Quality recommended a separation between the two terms, with soil quality being a more analytical and quantitative term (Karlen et al., 1997)
Terms are now used interchangeably in both scientific literature and the media. Soil health generally refers to the condition of a soil as a result of management while soil quality refers to both the condition of the soil and its inherent properties.

10. 2013
The Year of Soil Health for the USDA- NRCS (Natural Resources Conservation Service)

11. Why Soil Quality is Important
Soil degradation is a major world-wide problem
The vast majority of agricultural land in the US already has depleted levels of SOM
Poor soil health can lead to reduced yields and reduced profits

12. Nutrients are lost through leaching and soil erosion in degraded soil
A healthy stable soil absorbs and holds water better and leads to better water infiltration and erosion control

13. What Healthy Soil Does Gives us clean air and water
Productive crops and forests
Productive grazing lands
Diverse wildlife and landscapes.

14. Soil does all this by performing four essential agricultural functions:
Regulating water
Sustaining plant and animal life
Filtering potential pollutants
Cycling nutrients

15. Soil quality cannot be measured directly, so we evaluate indicators.
Indicators are measurable properties of soil or plants that provide clues about how well the soil can function.
Indicators can be physical, chemical, and biological properties, processes, or characteristics of soils. 
They can also be morphological or visual features of plants.

16. Useful indicators:
are easy to measure,
measure changes in soil functions
encompass chemical, biological, and physical properties
are accessible to many users and applicable to field conditions
are sensitive to variations in climate and management.

17. Soil Quality Indicators
Relationship to Soil Health
Soil organic matter (SOM)
Soil fertility, structure, stability, nutrient retention; soil erosion
Physical: soil structure, depth of soil, infiltration and bulk density; water holding capacity
Retention and transport of water and nutrients; habitat for microbes; estimate of crop productivity potential; compaction, plow pan, water movement; porosity; workability
Chemical: pH; electrical conductivity; extractable N-P-K
Biological and chemical activity thresholds; plant and microbial activity thresholds; plant available nutrients and potential for N and P loss
Biological: microbial biomass C and N; potentially mineralizable N; soil respiration. 
Microbial catalytic potential and repository for C and N; soil productivity and N supplying potential; microbial activity measure 

18. Although soil characteristics are indicators of soil quality, soil quality must be identified by how soil performs its functions.
The ultimate purpose of assessing soil quality is not to achieve high aggregate stability, biological activity, or some other soil property
The purpose of soil quality improvement is to protect and improve long-term agricultural productivity, water quality, and the habitats of all organisms, including people.
NRCS soil health website

19. Soil quality assessments require measuring the current state of an indicator and comparing the results to known or desired values (Karlen et al., 1997)

20. Why Assess Soil Quality
Awareness and education
Assessment as an adaptive management tool
Evaluation of alternative practices
Assessment as a monitoring tool

21. Types of Soil Quality Assessment Tools
Qualitative Scorecards – Farmer driven with NRCS
Field Test Kits – NRCS or commercially available
Lab-based assessments
Soil Management Assessment Framework
Cornell Soil Health Assessment
Practice Predictors - use research outcomes to predict the effects of management practices on soil quality.
NRCS Soil and Water Eligibility Tool (SWET)
Conservation Measurement Tool (CMT)
Landscape-level assessments - use satellite and remote sensing technology to assess resource quality at large spatial scales.

22. University of Missouri Soil Health Lab
Active Carbon pH
Aggregate Stability
Available P
Mineralizable N
PLFA
Total Carbon
Infiltration
SMAF SQI

23. Soil Organic Matter is one of most important soil quality indicators
Comprises only a tiny fraction of total mass of most soils (<3% in MO)
Exerts a dominant influence on many soil chemical, physical and biological properties

24. Much of water holding capacity of surface soils
Stabilizes soil surface, increases infiltration, plant available water, decreases erosion
Majority of cation exchange capacity of surface soil
Formation and stabilization of soil aggregates
Contains large amounts of plant nutrients
Supplies energy for soil microorganisms

25. Why focus on soil organic matter?
Affects several critical soil functions,
Can be manipulated by land management practices
Important in most agricultural settings across the country
Enhances water and nutrient holding capacity
Improves soil structure,
Managing for soil carbon can enhance productivity and environmental quality, and can reduce the severity and costs of natural phenomena, such as drought, flood, and disease
Increasing soil organic matter levels can reduce atmospheric CO2 levels that contribute to climate change

26. Soil organic matter and its major constituent, organic carbon, can be depleted from soil during tillage
Effect of 10 years of conventional till and no-till on OC (calculated from SOM data in Edwards et al., 1999).
Soil profile organic carbon concentration under plow till, chisel till, no till, pasture and forest.
Puget and Lal, 2005

27. Rapid declines in organic C were seen in the Morrow and Sanborn Field plots after cultivation began.
Sanborn Field removed crop residue until the 1950s, so the decline in SOC was faster there. SOC increased slightly when residue management was changed and residue was left on fields

28. Soil organic carbon (SOC), which makes up about half of soil organic matter, can be divided into active, slow and passive soil carbon pools
Active Carbon
Active carbon fuels the soil food web and includes microbial biomass, particulate organic matter, soil carbohydrates and rapidly mineralizable carbon. The active carbon pool can be measured and used as an indicator of differences in management.

29. Potassium Permanganate Test
KMnO4 oxidizes active carbon. The purple color of the chemical changes to pink the more active carbon there is in a soil sample.
Results are read in a spectrometer in lab or field or from a color card

30. Soil Structure Arrangement of soil solids and voids
Soil structure influences water infiltration and retention, erosion, crusting, nutrient recycling, root infiltration and crop yield
Expressed as degree of aggregate stability
Aggregation is controlled by SOC, microorganisms, ionic bridging, clay

31. Aggregate Stability Fungal-produced glomalin helps bind aggregates
Wright, et al., 1999
Aggregate Stability
Fungal-produced glomalin helps bind aggregates
Measured with wet sieving

32. Tillage reduces aggregate stability and sizes
Chen et al., 2000

33. Water Infiltration
Good infiltration allows for less runoff and erosion
Soils with poor aggregate stability will crust, damaging emerging seedlings and increasing runoff

34. Improving Soil Quality
Different soil types and land uses call for different management practices but general goals are:

35. Enhance organic matter
Leave crop residues in the field
Choose crop rotations that include high residue plants
Use optimal nutrient and water management practices to grow healthy plants with large amounts of roots and residue
Grow cover crops
Apply manure or compost
Use low or no tillage systems  

36. Avoid excessive tillage
Reducing tillage minimizes the loss of organic matter and protects the soil surface with plant residue
Tillage
Breaks up soil structure
Speeds the decomposition and loss of SOM
Increases erosion
Destroys the habitat of helpful organisms
Causes compaction.

37. Manage pests and nutrients efficiently
Soil buffers and detoxifies chemicals when not overloaded
Pesticides and chemical fertilizers can harm non-target organisms and pollute water and air if they are mismanaged.
Nutrients from organic sources also can pollute when misapplied or over-applied.
Management
test and monitor soil and pests
apply only the necessary chemicals, at the right time and place
taking advantage of non-chemical approaches to pest and nutrient management such as crop rotations, cover crops, and manure management  

38. Prevent soil compaction
Compaction reduces the amount of air, water, and space available to roots and soil organisms.
Compaction is caused by repeated traffic, heavy traffic, or traveling on wet soil.
Deep compaction by heavy equipment is difficult or impossible to remedy, so prevention is essential.  

39. Keep the ground covered
Reduces wind and water erosion and drying and crusting.
Protects soil and provides habitats for larger soil organisms
Can improve water availability.
Management
Leave crop residue on the surface
Plant cover crops   .

40. Diversify cropping systems
Diversity of soil organisms helps control pests
Diversity of cultural practices can reduce weed and disease pressures
Diversity across the landscape can be increased by using buffer strips, small fields, or contour strip cropping
Diversity over time can be increased with long crop rotations
Changing vegetation across the landscape or over time increases the types of insects and microorganisms

41. Bradford Summer Cover Crop Mix: millet, sunflower, cowpea, buckwheat, sunn hemp, sorghum-sudangrass
Legumes underlined

42. Bradford Winter Cover Crop Mix: cereal rye, hairy vetch, Austrian winter pea, crimson clover, tillage radish, oats
Legumes underlined