ADDRESSING THE SOIL ADDRESSING THE SOIL COMPACTION PROBLEMCOMPACTION PROBLEM

DICK WOLKOWSKIEXTENSION SOIL SCIENTISTUNIVERSITY OF WISCONSIN

SOIL COMPACTION DEFINED

Compression of the soil Compression of the soil from an applied force from an applied force that first rethat first re--arranges arranges and then destroys and then destroys aggregates increasing aggregates increasing bulk density and bulk density and reducing porosity reducing porosity

•• Wheel traffic from Wheel traffic from field operationsfield operations

•• TillageTillage•• LivestockLivestock

Soil compacts when load-bearing strength of soil is less than load being applied.

Load

StrengthMoisture

Structure Texture

Tillage History

“COMPACTABILITY” INFLUENCED BY WATER CONTENT

•• Varies by soilVaries by soil•• Maximum near field Maximum near field

capacity capacity •• Dry soil has more strengthDry soil has more strength•• Saturated soil not as Saturated soil not as

compactablecompactable

Proctor Test Results

DDbb = 1.0= 1.0 DDbb = 1.3 Db = 1.6

COMPACTION IS A PROCESSCOMPACTION IS A PROCESS

•• Large aggregates Large aggregates •• Loose conditionLoose condition•• Many large poresMany large pores•• Well aeratedWell aerated•• Just after tillageJust after tillage

•• Firm conditionFirm condition•• Few large poresFew large pores•• Moderate aerationModerate aeration•• Typical silt loamTypical silt loam•• Following normal Following normal

traffictraffic

•• Very tight, compactVery tight, compact•• No large poresNo large pores•• Small pores are Small pores are

waterwater--filledfilled•• Crushed aggregatesCrushed aggregates

WHY IS COMPACTION AN ISSUE

Larger equipmentLarger equipment Time managementTime managementEarlier field operationsEarlier field operations Uncontrolled trafficUncontrolled trafficLoss of forage in rotationLoss of forage in rotation Brain crampsBrain crampsOperations on wet soilsOperations on wet soils

Will more tires spread weight … or allow operations in wetter conditions and compact a greater soil volume ?

WHICH IS WORSE – PRESSURE OR LOAD?

High PSI, but small load High PSI, but small load

THE GREATER THE LOAD THE THE GREATER THE LOAD THE DEEPER THE COMPACTION EFFECT DEEPER THE COMPACTION EFFECT

Low PSI, but large load Low PSI, but large load

TRACKS vs. TIRES

Compare total load per axleCompare total load per axle

Track have many axlesTrack have many axles

There really are days you shouldn’t be in the field !

Chasing the combineis an old habit

CONTROL PHEASANTSCOMPACTION BYUNLOADING IN HEADLANDS

MOST OF THE COMPACTION OCCURS IN THE FIRST PASS

•• Plano silt loamPlano silt loam•• Soil near field Soil near field

capacity (34 capacity (34 –– 38%)38%)•• 2007 NT w. wheat2007 NT w. wheat

2006 NT corn silage 2006 NT corn silage following alfalfafollowing alfalfa

•• Chisel vs. NoneChisel vs. None•• No traffic or 1, 2, 4, No traffic or 1, 2, 4,

and 6 passes with a and 6 passes with a 14.5 ton combine14.5 ton combine

•• 6 measurements per 6 measurements per treatmenttreatment

Arlington EvaluationArlington Evaluation

EFFECT OF NUMBER OF WHEEL TRAFFIC PASSES ON SOIL COMPACTION

0

4

8

12

16

20

0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8

Cone Index (MPa)

Dep

th (i

n)

No Traffic 1 Pass 2 Passes 4 Passes 6 Passes

0

4

8

12

16

20

0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2

Cone Index (MPa)

No Traffic 1 Pass 2 Passes 4 Passes 6 Passes

Chisel PlowedChisel Plowed Not PlowedNot Plowed

COMMOM SYMPTOMS OF SOIL COMPACTION

SOIL:SOIL:•• Standing waterStanding water•• Excessive runoffExcessive runoff•• Structural degradation Structural degradation

(clods)(clods)•• Difficult to workDifficult to work

PLANTS:PLANTS:•• Stunting/uneven Stunting/uneven

growthgrowth•• Nutrient deficiency Nutrient deficiency

symptomssymptoms•• Malformed rootsMalformed roots•• Reduced yieldReduced yield

Pea harvest: Vegetable crop contracts often lead to soil abuse

Utility construction projects

“Cloddy” soil following corn silage harvest

Cloddiness re-defined

Stunted, uneven stand is often the first symptom

The shovel is an excellentdiagnostic tool

Northeast Wis.field day

GROWERS ARE INTERESTED IN GROWERS ARE INTERESTED IN COMPACTION MANAGEMENTCOMPACTION MANAGEMENT

Excavatedplow layer

“Pancake”root mass

QUANTIFYING COMPACTION• CROP AND SOIL SYMPTOMS

• PENETRATION RESISTANCE–– Moisture dependentMoisture dependent–– No absolute valueNo absolute value–– Note depth and Note depth and

relative forcerelative force–– Compare good and Compare good and

bad areasbad areas

• BULK DENSITY–– Mass per volumeMass per volume–– Calculate porosityCalculate porosity–– Texture dependentTexture dependent

MEASURING PENETRATION RESISTANCE

Hand-held penetrometer

Soil probe

CONSTANT-RATE RECORDING PENETROMETER

0

5

10

15

20

25

30

35

40

45

50

0 0.5 1 1.5 2 2.5

Cone Index (MPa)

Dep

th(c

m)

Series1

Series2

Series3

Series4

Compaction/Subsoiling

No/NoNo/YesYes/NoYes/Yes

Response of a Plainfield sand to Response of a Plainfield sand to compaction and deep tillage, Hancock, Wis.compaction and deep tillage, Hancock, Wis.

7/20/2000Avg. water content = 27 %

6/22/2000Avg. water content = 36 %

0 1000 2000 3000 4000

Soil Resistance to Penetration, kPa

500

450

400

350

300

250

200

150

100

50

0D

epth

, mm

No-Compaction - No-tillageNo-Compaction - ChiselCompacted - No-TillageCompacted - Chisel

7/20/20006/22/2000

SOIL WATER CONTENT AFFECTS PENETRATION RESISTANCE.

ARLINGTON, WIS.PLANO SILT LOAM SOIL

EFFECT OF COMPACTION ON SOIL BULK DENSITY OF A PLANO SILT LOAM

Compacted in year 1 and seeded to alfalfa

DEPTHDEPTH COMPACTIONCOMPACTION YEAR 1YEAR 1 YEAR 2YEAR 2 YEAR 3YEAR 3inin -------------------------------------- g/cc g/cc --------------------------------------

0 0 –– 66 NONO 1.191.19 1.301.30 1.321.32YESYES 1.361.36 1.401.40 1.401.40

6 6 -- 1212 NONO 1.311.31 1.331.33 1.311.31YESYES 1.591.59 1.501.50 1.521.52

12 12 -- 1818 NONO 1.191.19 1.351.35 1.331.33YESYES 1.451.45 1.441.44 1.331.33

18 18 -- 2424 NONO 1.361.36 1.351.35 1.341.34YESYES 1.401.40 1.341.34 1.331.33

COMPACTION AFFECTS NUTRIENT UPTAKE

Potassium Affected Most• Compaction reduces porosity• Lowers soil oxygen• O2 needed for root respiration and

active uptake

COMPACTION EFFECT ON CORN YIELD ON A SILTY CLAY LOAM SOIL

120

130

140

150

160

170

180

1985 1986 1987

YIEL

D (b

u/a)

<5 t9 t19 t

Oshkosh, Wis.

RESPONSE OF CORN TO ROW-APPLIED K ON A SILTY CLAY LOAM SOIL (3 yr. avg.)

0

5

10

15

20

25

30

35

< 5 t 19 t

YIEL

D R

ESPO

NSE

(bu/

a)

OPTIMUMV. HIGH

Oshkosh, Wis. (45 lb K2 0/a)

SOIL TEST K

IS COMPACTION A PROBLEM IN FORAGE PRODUCTION

•• Compaction limits growth and yieldCompaction limits growth and yield•• Potential high in forage productionPotential high in forage production

•• Fertilizer and lime applicationsFertilizer and lime applications•• Liquid manureLiquid manure•• Normal management = many traffic Normal management = many traffic

passespasses•• Harvest on wet soilsHarvest on wet soils

•• K/compaction relationshipK/compaction relationship•• Alfalfa has a high K needAlfalfa has a high K need

Alfalfa winter-kill resulting fromwheel traffic

EFFECT OF COMPACTION ON ALFALFA YIELD ON A SILT LOAM SOIL

0

1

2

3

4

5

1991 1992 1993 1994

YIEL

D (t

DM

/a) < 5 T

14 T

Arlington, Wis.

K SOIL TEST AND ALFALFA YIELD ON A COMPACTED SOIL (sum of 3 yrs.)

8

9

10

11

12

< 5 t 14 t

YIEL

D (t

DM

/a)

OPT HIGH V. HIGH

Arlington, Wis.

SOIL TEST K

DETERMINING THE NEED FOR SUBSOILING

•• Evaluate depth and severity of compactionEvaluate depth and severity of compaction•• Check with penetrometer, probe, shovelCheck with penetrometer, probe, shovel•• Dig plants to examine rootsDig plants to examine roots•• Leave untreated strips for comparisonLeave untreated strips for comparison•• Subsoiling is not a cureSubsoiling is not a cure--allall

CONVENTIONAL TILLAGE CAN REMOVE SHALLOW COMPACTION

0

0.5

1

1.5

2

2.5

3 6 9 12 15 18 21 24 27 30 33 36 39 42 45DEPTH (cm)

RES

ISTA

NC

E (M

Pa) None

MBCHNTST

Arlington, Wis., 2002 (6 t vehicle)

PENETROMETER RESISTANCE FOLLOWING TILLAGE OF A “LIGHTLY” COMPACTED SILT LOAM SOIL

OTHER SUBSOILING CONSIDERATIONSOTHER SUBSOILING CONSIDERATIONS

•• Burial of crop residueBurial of crop residue•• Destruction of natural channelsDestruction of natural channels•• Sidewall smearingSidewall smearing•• May bring stones, clay, infertile soil to the May bring stones, clay, infertile soil to the

surfacesurface•• Does not address compaction causeDoes not address compaction cause

SOIL BULK DENSITY PROFILE, ARLINGTON, WIS., 1998

0.8 - 0.90.9 - 11 - 1.11.1 - 1.21.2 - 1.31.3 - 1.4

Not subsoiled

Subsoiled

Bulk Density (g/cc)

PLANO SILT LOAM

R R

RR

0

8

16

0

8

16

Depth (in)

EFFECT OF TILLAGE AND K FERTILIZATION ON FIRST- YEAR CORN YIELD AFTER SOYBEAN (2 yr. avg.)

50

100

150

200

250

NONE SUBSOIL CHISEL

YIEL

D (b

u/a)

NONE 50 lb K2O 100 lb K2OArlington, Wis.

WHICH TYPE OF SUBSOILER

“V-Ripper”- Leading disks- Parabolic shanks- Winged points

““Conservation”Conservation”-- Cutting coultersCutting coulters-- Straight shanksStraight shanks-- Horizontal pointsHorizontal points

EFFECT OF SUBSOILER TYPE ON SOYBEAN AND CORN YIELD ON A SILTY

CLAY LOAM SOIL

20

25

30

35

40

45

50

55

60

1997 1999

YIEL

D (b

u/a)

NO-TILL V-RIPPER STRAIGHT

160

170

180

190

200

210

220

230

1998 2000YI

ELD

(bu/

a)

Manitowoc, Wis.

Soybean Corn

DON’T COUNT ON MOTHER NATURE TO CORRECT COMPACTION

WADSWORTH TRAIL, MINNESOTA

0.8 0.9 1 1.1 1.2 1.3

OUTSID

E RUTS

IN R

UTS

SOIL BULK DENSITY (g/cc)

10-12 in 8-10 in 6-8 in4-6 in 2-4 in 0-2 in

Sharratt et al., 1998Sharratt et al., 1998

Guidelines for managing compaction:1. Stay off wet soils

Get the point ?

Guidelines for managing compaction:2. Control traffic – Unload on field edge

Guidelines for managing compaction:2. Control traffic – No shortcuts

Guidelines for managing compaction:3. Limit load weight – Practical considerations

Guidelines for managing compaction:3. Limit load weight – Avoid operations with heavy loads when possible

OTHER KEYS FOR MANAGING SOIL COMPACTION

Evaluate and monitor crops and soilEvaluate and monitor crops and soil•• Subsoil only if documented Subsoil only if documented

compaction conditions existcompaction conditions exist•• Use common senseUse common sense•• Address compaction issuesAddress compaction issues•• FactsheetFactsheet A3367 currently being A3367 currently being

revisedrevised