managing soil compaction in agricultural fields
TRANSCRIPT
RESEARCH
Managing Soil Compaction in
Agricultural Fields
Randy L. RaperOklahoma Agricultural Experiment
StationOklahoma State University
RESEARCH
Advice to Manage Soil Compaction
• Only traffic when soil moisture is low!• Adopt conservation agricultural system including cover
crops!• Use controlled traffic systems!• Use smallest vehicle possible for job!• Minimize inflation pressure in radial tires!• Reduce contact pressure by using duals or tracks!
• If necessary to remove effect of traffic, use in-row or bentleg subsoilers that minimally disturb soil surface and only till slightly below depth of compaction!
RESEARCH
What is soil compaction?
Quite simply, it is a reduction in pore space.Quite simply, it is a reduction in pore space.
RESEARCH
Why is Soil Compaction Important?
• Reduced Crop Yields– Reduced root growth– Decreased infiltration– Increased erosion
RESEARCH
Causes of soil compaction
• Vehicle Traffic
RESEARCH
Vehicle Traffic
0
10000
20000
30000
40000
50000
60000
Weight, lbs.
1948 2000
RESEARCH
Vehicle Traffic
RESEARCH
New Equipment: 80,000#!
RESEARCH
Sample Pressures Exerted on the Soil
5 – 23 psi
30 psi
56 psi
RESEARCH
Cone Resistance (MPa)Cone Resistance (MPa)00 22 33 44 5511
00
5050
1010
2020
3030
4040
Depth (cm
)Depth (cm
)
Not grazedNot grazed
GrazedGrazed
Short-term Grazing
RESEARCH
Causes of soil compaction
• Vehicle Traffic• Natural Soil
Reconsolidation
RESEARCH
Causes of soil compaction
• Vehicle Traffic• Natural Soil
Reconsolidation– Well-graded soils
more susceptible to compaction than poorly- graded soils
0
20
40
60
80
100
0.0010.110
Particle Diameter, mm
Percent Finer
Poorly-Graded
Well-Graded
RESEARCH
Measurement of soil compaction
• Bulk Density– Time consuming
– Difficult to compare across soil types
RESEARCH
Measurement of soil compaction
• Bulk Density• Soil Cone Penetrometer
– Standardized unit• ASAE Standard S313• ASAE Engineering Practice EP542
– Quickly obtain information
– Researchers have related results to crop response
• 300 psi (2 MPa) restricts root growth
Cone Resistance (MPa)Cone Resistance (MPa)00 22 33 44 5511
00
5050
1010
2020
3030
4040
Depth (cm
)Depth (cm
)
Not grazedNot grazed
GrazedGrazed
RESEARCH
Handheld Penetrometer
RESEARCH
Recording Penetrometer
RESEARCH
Multiple-probe PenetrometerPositions of Penetrometer
Measurements
RESEARCH
Commercial Tractor-Mounted
Penetrometer
RESEARCH
Advice to Manage Soil Compaction
• Only traffic when soil moisture is low!• Adopt conservation agricultural system including cover
crops!• Use controlled traffic systems!• Use smallest vehicle possible for job!• Minimize inflation pressure in radial tires!• Reduce contact pressure by using duals or tracks!
• If necessary to remove effect of traffic, use in-row or bentleg subsoilers that minimally disturb soil surface and only till slightly below depth of compaction!
RESEARCH
Preventing it
• Avoid Weak Soil– Moisture Content
Effect
Liquidity index
-0.6 -0.4 -0.2 0.0 0.2 0.4 0.6P
re-c
ompr
essi
on s
tres
s, k
Pa
1
10
100
1000
RESEARCH
Advice to Manage Soil Compaction
• Only traffic when soil moisture is low!• Adopt conservation agricultural system including cover
crops!• Use controlled traffic systems!• Use smallest vehicle possible for job!• Minimize inflation pressure in radial tires!• Reduce contact pressure by using duals or tracks!
• If necessary to remove effect of traffic, use in-row or bentleg subsoilers that minimally disturb soil surface and only till slightly below depth of compaction!
RESEARCH
Conservation Agricultural System
• Reduced Vehicle Traffic– Conventional Tillage System
• 80% of field may be trafficked from numerous field operations
• 1st pass is responsible for 80% of compaction
– Conservation Agricultural System• Greater soil strength in row middles• Plant into old rows – controlled traffic• Reduced number of field trips - reduced compaction
over entire field
RESEARCH
2020 1010 00 1010 2020
44
88
1212
1616
2020
2424
Distance from Row (in)Distance from Row (in)
Dep
th (
in)
Dep
th (
in) 1515
2020
20202020
2525
2020
Cover CropCover CropCover Crop15%1515%%
20%2020%%
25%2525%%
15%1515%%
20%2020%%
25%2525%%
0-6”00--66””
6-12”66--1212””
2020 1010 00 1010 2020
44
88
1212
1616
2020
2424
Distance from Row (in)Distance from Row (in)
Dep
th (
in)
Dep
th (
in) 1515
1515
15151515
20202020
Cover CropCover CropCover Crop15%1515%%
20%2020%%
25%2525%%
15%1515%%
20%2020%%
25%2525%%
0-6”00--66””
6-12”66--1212””
No-Till
RESEARCH
Yield Improvements with Cover Crops
b
b
a
a
0
1000
2000
3000
4000
5000
2003 2004 2005 2006Year
Yie
ld (
kg/h
a)
No Cover Cover
ns
ns
RESEARCH
Advice to Manage Soil Compaction
• Only traffic when soil moisture is low!• Adopt conservation agricultural system including cover
crops!• Use controlled traffic systems!• Use smallest vehicle possible for job!• Minimize inflation pressure in radial tires!• Reduce contact pressure by using duals or tracks!
• If necessary to remove effect of traffic, use in-row or bentleg subsoilers that minimally disturb soil surface and only till slightly below depth of compaction!
RESEARCH
Controlled Traffic
• Wide-span vehicles
RESEARCH
Controlled Traffic
• Wide-span vehicles• Wide-span tractors
RESEARCH
Controlled Traffic
• Wide-span vehicles
• Wide-span tractors
• Automatic-steered tractors
RESEARCH
Uncontrolled Traffic!
RESEARCH
Controlled Traffic Using Autosteer
RESEARCH
9”
}}
2”
Yield Reductions from Uncontrolled
Traffic
• 16% reduction from misalignment of row and strip-tilled zone by 2”.
• 29% reduction from misalignment of row and strip-tilled zone by 9”.
RESEARCH
Advice to Manage Soil Compaction
• Only traffic when soil moisture is low!• Adopt conservation agricultural system including cover
crops!• Use controlled traffic systems!• Use smallest vehicle possible for job!• Minimize inflation pressure in radial tires!• Reduce contact pressure by using duals or tracks!
• If necessary to remove effect of traffic, use in-row or bentleg subsoilers that minimally disturb soil surface and only till slightly below depth of compaction!
RESEARCH
Preventing Soil Compaction
Research Summary
• Assuming moist, arable soil:– 4.4 tons/axle compacts to
12 in.– 6.6 tons/axle compacts to
15.8 in.– 11 tons/axle compacts to
19.7 in.– 16.5 tons/axle compacts to
23.6 in. and deeper• Common to see
persistence of subsoil compaction 6-7 years later.
Hakaansson, and Reeder, 1994
RESEARCH
Approximate Axle LoadsEquipmentEquipment Axle LoadAxle Load
(ton/axle)(ton/axle)
100 hp 2100 hp 2--wheel drive tractorwheel drive tractor 44
200 hp 2200 hp 2--wheel drive tractorwheel drive tractor 88
320 hp 4320 hp 4--wheel drive tractorwheel drive tractor 99
66--row combine (empty)row combine (empty) 1111
1212--row combine (full)row combine (full) 2626
Single axle 27 ydSingle axle 27 yd33 grain cart (full)grain cart (full) 2222
Double dualDouble dual--axle 50 ydaxle 50 yd33 manure tanker manure tanker (full)(full)
35 (rear)35 (rear)
13 (front)13 (front)
RESEARCH
Advice to Manage Soil Compaction
• Only traffic when soil moisture is low!• Adopt conservation agricultural system including cover
crops!• Use controlled traffic systems!• Use smallest vehicle possible for job!• Minimize inflation pressure in radial tires!• Reduce contact pressure by using duals or tracks!
• If necessary to remove effect of traffic, use in-row or bentleg subsoilers that minimally disturb soil surface and only till slightly below depth of compaction!
RESEARCH
Radial Tires
6 psi18 psi
RESEARCH
Stresses (kPa) on Lug at 6 tons/axle
AXLE
FRONT
REARInflation Pressure = 41 kPa Inflation Pressure = 124 kPa
6 psi 18 psi
RESEARCH
Tractive Performance Data
RESEARCH
Goodyear Farm, Specialty, and Terra Tire Goodyear Farm, Specialty, and Terra Tire HandbookHandbook
RESEARCH
Advice to Manage Soil Compaction
• Only traffic when soil moisture is low!• Adopt conservation agricultural system including cover
crops!• Use controlled traffic systems!• Use smallest vehicle possible for job!• Minimize inflation pressure in radial tires!• Reduce contact pressure by using duals or tracks!
• If necessary to remove effect of traffic, use in-row or bentleg subsoilers that minimally disturb soil surface and only till slightly below depth of compaction!
RESEARCH
Benefits of Duals
SingleDuals
Taylor et al., 1975
RESEARCH
Ground Pressure under a Loaded Rubber Belt
Tractor
200
0
Rear Roller
Front Roller
12614 lbs.
Turner et al., 1997.
RESEARCH
Ground Pressure under a Loaded MFWD
Tractor
200
0
Rear TireFront Tire
12656 lbs.
Turner et al., 1997.
RESEARCH
Effects of Duals and Tracks on Soil
Density
1.3
1.35
1.4
1.45
1.5
1.55
1.6
1.65
'10-20 '20-30 '30-40 '40-50
Depth, cm
Dry
Den
sity
, gm
/cc
D-overC65C75D-correctUntraffic
Abu-Hamdeh et al., 1995
RESEARCH
Width of Footprint
Dual Tires Track
RESEARCH
Advice to Manage Soil Compaction
• Only traffic when soil moisture is low!• Adopt conservation agricultural system including cover
crops!• Use controlled traffic systems!• Use smallest vehicle possible for job!• Minimize inflation pressure in radial tires!• Reduce contact pressure by using duals or tracks!
• If necessary to remove effect of traffic, use in-row or bentleg subsoilers that minimally disturb soil surface and only till slightly below depth of compaction!
RESEARCH
Moldboard Plowing
RESEARCH
Strip Till, In-Row Subsoil,
Non-inversion Subsoil
RESEARCH
Straight Shanks
RESEARCH
Bentleg Shanks
RESEARCH
Residue Cover After In-Row Subsoiling
0
20
40
60
80
100
8 12 16
Tillage Depth (in)
Percent Residue Rem
aining (%)
KMC
Paratill
Terramax
RESEARCH
Tillage Effect on Seed Cotton Yield
Tennessee Valley Soil in Northern AL
RESEARCH
Subsoiling Forces
0
1
2
3
4
5
6
9 12 15
Tillage Depth (in)
Draft Force (kN
)
RESEARCH
Completely Subsoiled 5 Years Previous
RESEARCH
Advice To Manage Soil Compaction:
• Only traffic when soil moisture is low!• Adopt conservation agricultural system including cover
crops!• Use controlled traffic systems!• Use smallest vehicle possible for job!• Minimize inflation pressure in radial tires!• Reduce contact pressure by using duals or tracks!
• If necessary to remove effect of traffic, use in-row or bentleg subsoilers that minimally disturb soil surface and only till slightly below depth of compaction!
