what is soil health? managing wisconsin soils for improved
TRANSCRIPT
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Managing Wisconsin Soils for Improved Soil Health and
Reducing Compaction
Francisco J. ArriagaAssistant Professor and Extension Specialist
Soil and Water ManagementUW-Extension and Dept. of Soil Science
Enhancing Your Agronomic Systems WorkshopFebruary 7, 2017 1
What is Soil Health?
• Ability of a soil to function in a way that benefits both humans and the environment
• This assumes there is a baseline (i.e. maximum potential) for different soils
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Functions of Soil
source: Brady & Weil, 1996
Engineering medium
Recycling systemfor nutrients andorganic wastes
Habitat forsoil organisms
System forwater supply
and purification
Medium forplant growth
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Soil Health Indicators(or Soil Properties that Influence Function)
Physical Chemical
Biological
•density•infiltration•water retention•aggregation
•nutrient availability•pH•CEC
•organic matter•biological activity•roots•organisms
Soil Health
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Soil Health in Wisconsin
Three Step Program
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Step 1. Maintain Proper Soil Fertility
• It is important for crop production to begin with soils that are properly managed from a fertility stand point.
• The acidity of the soil, or pH, is one such fertility parameter that must be managed to have adequate conditions for the biology of the soil and crops.
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Step 2. Increase/Maintain Soil Carbon
• The total amount of soil organic carbon in the soil is important.
• Crop rotations and cover crops can help add soil organic carbon variety to the soil.
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Organic Matter Decomposition
Hummus Crop residues
Roots & mycorrhizaeOther livingorganisms
(Al‐Kaisi,2016 )8
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• Definition of Cation Exchange Capacity (CEC): 1) amount of negative charge per unit quantity of oven dry soil; 2) the capacity to adsorb cations from solution.
• The negative charge on the surfaces of clay particles holds cations– Reduces leaching– Exchange with soil solution– Storehouse of fertility
Soil Chemical Properties:Cation Exchange Capacity (CEC)
• CEC is expressed in milli-equivalents (meq) per 100 g of soil
Sands: 3 – 5 meq/100 gSilt loam: 15 – 25 meq/100 gClays: 20 – 50 meq/100 gOrganic materials: 50 – 100 meq/100 g
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Step 3. Improve Soil Aggregation
Adapted from http://vro.depi.vic.gov.au/
WATER
Poor or no aggregationGood aggregation
WATER
Adapted from http://cnrit.tamu.edu/
Aggregation, Water Infiltration and Flow in Soils10
Dry Aggregate Size Distribution
• Stack of sieves of different size openings:– 9.5 mm– 4.75 mm– 2.0 mm– 1.00 mm– 0.50 mm– Pan (“loose soil)
opening
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Dry Aggregate Size Distribution
2016
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Dry Aggregate Size Distribution
Field Natural
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Soil Organic Matter
At current organic carbon accumulation rates, it would take:• 1.7 years to reach a SOM of 2%• 6.6 years to reach a SOM of 3%
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You‐Tube video: “Soil Aggregation and Water Infiltration”Univ. of Wisconsin Integrated Pest and Crop Management Program
https://youtu.be/d1M7EFqqsMM
Organic matter oxidationConc. H2O2
CT Roto‐tilled NT
photos: F. Arriaga, Soil Science
Aggregate stabilitySlake test
NT Roto‐tilled CT
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Water InfiltrationField Day August 2013
photos: Roger Schmidt, NPM Program
Conventional No‐tillage
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What is the Link Between
Soil Health
and
Soil Compaction?
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What is Soil Compaction?
Soil Water Air
compaction
soil not compacted compacted soil
Compaction reduces the amount of pore spaces in the soil, which in turns reduces aeration, water retention, and water movement in the soil.
Soil Compaction Destroys AggregatesOverall Reduction in Pore Space
(adapted from USDA Ag Bulletin 199)
granular
blocky
massive
compaction
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Causes of Soil Compaction
1. Traffic when soil is too wet.2. High axle loads3. Overinflated tires (high tire pressure)
Causes of Soil Compaction
4. Traffic patterns and repeated traffic.
Merger, chopper, and six trucks Cover crop stand
Image: Brian Luck
Image: Bill Halfman, UW‐Extension Monroe Co
Causes of Soil Compaction
5. Poor soil aggregation.
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Loam
(Blanco‐Canqui,2009)
Low disturbance
High disturbance
Weight Bearing Capacity of SoilChisel plowed No tillage
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Aggregate Formation/Stability Concept
(Six et al. SSSAJ, 1999)
Energy in the organic matter “wasted” to re‐form aggregates
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Aggregate Disruption and Soil Compaction
(Blanco‐Canqui,2009)26
High disturbance
Low disturbance
Soil Bulk Density Affects Residue Decomposition(i.e. reduction in soil microbial activity)
(De Neve,2000 )
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Soil density(grams/cc)
Types of Soil Structure
www.vaderstad.com
soilquality.org
colbydigssoil.com
colbydigssoil.com wps.prenhall.com
www.omafra.gov.on.ca
www.extension.org
Single Grained
Granular
Blocky
Prismatic Columnar
Platy
Massive
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Tillage & Soil Health Biological Indicators
(Moebius‐Clune et al.,2008 )
OM‐ Soil organic matter PMN – Potentially mineralizable NNem P – Parasitic nematodes EEG – Easily extractable glomalin conc.Nem B – Beneficial nematodes TG – Total glomalin concentrationDecomp – Cellulose decomposition rate
Continuous Corn System with Residue Harvest (32 years)
OM Nem P Nem B Decomp PMN EEG TG‐‐ % ‐‐ ‐‐ #/100g soil ‐‐ ‐ %/wk ‐ ‐ ppm/wk‐ ‐‐‐ mg/g soil ‐‐‐
No till unharvested 5.39 a 80 ab 320 a 8.93 a 1.73 a 1.73 a 6.63 aharvested 4.99 a 125 a 1140 a 2.45 b 1.65 a 1.12 b 4.90 bNT mean 5.19 A 103 A 730 A 5.69 A 1.69 A 1.42 A 5.76 A
Tilled unharvested 4.02 b 20 b 495 a 2.98 b 1.48 a 1.21 b 4.29 bharvested 3.71 b 10 b 315 a 2.63 b 0.55 a 1.09 b 4.21 bTill mean 3.87 B 15 B 405 A 2.80 B 1.01 B 1.15 B 4.25 B
• No‐tillage had a larger positive impact on improving indicators thanreturning corn residue to soil.
• Most sensitive indicators were: Db, AWC, OM, Decomp and TG 29
Closing Thoughts
• The three steps presented here are key for productivity of Wisconsin soil:
1. Maintain proper soil fertility
2. Increase/maintain soil organic carbon
3. Improve soil aggregation
• Soil compaction reduces soil porosity and destroys soil aggregation. Management that helps maintain and increase soil aggregation will also help keep soil compaction under control.
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Francisco J. ArriagaExtension Specialist
UW-Extension and Dept. of Soil ScienceUniversity of Wisconsin-Madison
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