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Overarching Principles of Soil Health

Francisco J. Arriaga Soil Management Specialist

Dept. of Soil Science & UW-Extension farriaga@wisc.edu

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.

Thank You! Any Questions?

Francisco J. Arriaga E-mail: farriaga@wisc.edu

Office phone: 608-263-3913