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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
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
Northeast Wis.field day
GROWERS ARE INTERESTED IN GROWERS ARE INTERESTED IN COMPACTION MANAGEMENTCOMPACTION MANAGEMENT
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
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
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: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