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Overarching Principles of Soil Health
Francisco J. Arriaga Soil Management Specialist
Dept. of Soil Science & UW-Extension [email protected]
608-263-3913
Wisconsin Chapter of the Soil and Water Conservation Society February 20, 2014
Functions of Soil & Soil Health
source: Brady & Weil, 1996
Soil health 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)
Soil Functions Indicators
• Medium for plant growth
• Recycle/store nutrients & organic materials
• Habitat for soil organisms
• Water storage & purification
• Texture • Structure • Infiltration & bulk density • Water holding capacity • Aggregate stability • Soil organic matter • pH • Extractable N,P, & K • Microbial biomass C & N • Potentially mineralizable N • Soil respiration
Soil as Three-Phase System
PHASES Solid:
Mineral Organic
Liquid:
Water & solutes Gas:
N2, O2, CO2 & others
50%
25%
25%
Phases SolidLiquidGas
Soil Structure
• Aggregates (peds)
Source: ATTRA - Soil Quality Publication
Aggregate Stability & Soil Health
• Influenced by – Organic matter and organisms – Texture – Rotation – Tillage
Soil Properties Affected by SOM
• Physical – infiltration – water retention – hydraulic conductivity – bulk density
• Chemical – CEC – nutrient availability – buffering capacity
source: soilquality.org A2809 Table 6.3
Role of Soil Organic Matter
Source: Magdoff and van Es, 2009
Physical soil properties
Chemical soil properties
Sands: 3 – 5 meq/100 g Silt loam: 15 – 25 meq/100 g Clays: 20 – 50 meq/100 g Organic soils: 50 – 100 meq/100 g
(Lado, Paz and Ben-Hur, 2004)
the Carbon Cycle
Source: Magdoff and van Es, 2009
Farming for Soil Organic Matter
(adapted from National Academy of Sciences, 2009)
0
500
1000
1500
2000
2500
0 10 20 30 40 50 60 70 80Time Since Plowing (days)
Cum
ulat
ive
CO
2 (kg
C/h
a)Moldboard No Till
How is Organic Matter Lost from Soil?
(Rochette and Angers, 1999)
Soil Carbon Accumulation & Management
(Tracy and Zhang, 2008)
continuous corn corn-oats-pasture cool-season grass warm-season grass
Water-stable Aggregates & Management
Source: Kladivko et al.
0
0.5
1
1.5
2
2.5
3
CC CSb SbC SbSb
SIZE
(mm
)
FALL MBFALL CHNO-TILL
Water Infiltration & Management
Water infiltration of five different tillage systems • NT=No-till
• ST=Strip-tillage (in-row)
• DR=Deep Rip
• CP=Chisel Plow
• MP=Moldboard Plow (Al-Kaisi, 2011)
Approximately ¼” of water is lost from the soil with every tillage pass.
source: M. Licht & M. Al-Kaisi, 2013
0
10
20
30
40
0 1 2 3 4 5 6
Soil
Wat
er C
onte
nt, %
Soil Organic Matter, %
WP %
FC %
0
10
20
30
40
0 1 2 3 4 5 6
Soil
Wat
er C
onte
nt, %
Soil Organic Matter, %
WP %
FC %
SOM & Soil Water Retention
2.2” 2.3” 2.4” 2.5” 2.5” 2.6” 2.7” Difference in Plant Available Water = 0.5 inches/ft
silt loam
0.8” 0.9” 0.9” 1.0” 1.0” 1.1” 1.2” Difference in Plant Available Water = 0.3 inches/ft4
loamy sand
Plant Available Water (PAW = FC – PWP)
(Stine & Weil, 2002)
Tillage: conventional reduced no-till
Corn Yield
• WDATCP WinTransect Data - Corn
Tillage Trends: 2000 – 2010
Tillage 2000 2005 2010
----------------------------- % ------------------------------
No-till 11 22 29
Chisel 39 33 58
Moldboard 49 43 5
Other 1 2 8
• WDATCP WinTransect Data - Soybean
Tillage Trends: 2000 – 2010
Tillage 2000 2005 2010
----------------------------- % ------------------------------
No-till 29 46 49
Chisel 39 34 38
Moldboard 22 19 5
Other 10 2 8
The amount of residue on the soil surface is directly related to the erosion rate
Crop Residue & Soil Crusts
Bare soil surface
Soil surface with cover
1.
Source: Magdoff and van Es, 2009
2.
Steps in Soil Crust Formation
Plant & Soil Sciences eLibrary
Allowable Amount of Soil Erosion
• Typical “T” (tolerable soil loss) factor in WI range between 3-5 ton/ac/year
• How fast does soil form in WI? – Wisconsin Glacial Period ended ~11,000 years ago – Assuming a 5’ deep profile, soil forms at a rate of
0.0055” per year (60”/11,000 years=0.0055”/yr)
– In other words, it takes ~180 years for 1” of soil to form naturally in WI
Allowable Amount of Soil Erosion
• But, how much is 1” of soil? – If a ft2 of soil to 1” depth weighs ~7.5 lbs (assumes Db =
1.45 g/cm3)
– Then, 1 acre of soil to 1” depth weighs 328,294 lbs, or 164 tons/ac
– Recall most “T” values in WI are 3-5 tons/ac/yr • 5 tons soil/acre = 3.7 ounces soil/ft2
Fertilizer Replacement Costs
• If a ton of soil has ~2.0 lb nitrogen, 9.0 lb P2O5 and 31 lb K2O (10 ppm N, 20 ppm P, and 130 ppm K)
• 2013 replacement costs of $8.80 per ton of soil lost: N = $1.00, P2O5 = $1.60, and K2O = $6.20 (assumes $450/ton urea, $350 ton of DAP, and $400/ton potash)
Soil Erosion Degrades Soil Health
source: S. Papiernik, 2013
Soil Erosion Impacts Crop Productivity
source: S. Papiernik, 2013
Why Does Soil Health Matters?
Source: Arriaga and Lowery, 2003a
Erosion level - Slight - Moderate - Severe
Compaction Destroys Aggregates
(adapted from USDA Ag Bulletin 199)
granular
blocky
massive
compaction
How Can the Health of a Soil be Improved?
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
(adapted from Karlen et al. SSSAJ , 1997)
It is About Management!
Source: Case Quick Start Guide
Licht & Al-Kaisi, 2004
Water Infiltration Field Day August 2013
photos: Roger Schmidt, NPM Program
Conventional No-tillage
Root Growth Field Day August 2013
photos: Roger Schmidt, NPM Program
Conventional No-tillage
Soil Organic Matter Field Day August 2013
Organic matter oxidation Conc. H2O2
Aggregate stability Slake test
CT Roto-tilled NT
photos: F. Arriaga, Soil Science
NT Roto-tilled CT
Rotation & Tillage Effect on Corn 0 lb N/ac 50 lb N/ac
200 lb N/ac 100 lb N/ac
224
190
160
128
95
60
30
0
224
190
160
128
95
60
30
0
224
190
160
128
95
60
30
0
224
190
160
128
95
60
30
0
Grai
n yi
eld,
bu/
acre
Continuous Corn Continuous Corn
Continuous Corn Continuous Corn
Corn Alfalfa
Corn Alfalfa Corn Alfalfa
Corn Alfalfa
Corn Soybean Corn Soybean
Corn Soybean Corn Soybean
(Stanger & Lauer, Agron. J. 2008) CC – chisel, disk & cultimulcher CA – no-till CS – no-till
Closing Remarks
• Organic matter (OM) improves physical and chemical soil properties. Soil biological properties are also improved.
• Healthy soils are achieved through management practices that enhance SOC accumulation.
