to compaction: 1 Assessing the inherent susceptibility based on texture and packing density. 2 Combining this soil susceptibility with an index of climatic.
Soil Compaction Jan van den Akker Catalin Simota Tom Hoogland
Introduction • Introduction • Risk Assessment Methods • Empirical RAM used for The Netherlands • Deterministic RAM used for The Netherlands • Dutch Soil Database: prediction subsoil compaction • Conclusions
Definition of subsoil
TOPSOIL PLOUGH PAN
SUBSOIL
Subsoil compaction is (partly) irreversible Effect
Resilience
-
---
+
0/-
--
-
0/-
-
--
Risk
topsoil ploughpan
subsoil
Human activities
Mechanical stress on soil surface (wheels, tracks or rollers of agricultural and construction machinery)
Air filled soil pore volume reduction Reduction of soil biological activity and soil productivity Decreased water infiltration capacity and increased erosion risk
Risk Assessment Methods 1 Empirical RAMs: based on measurements, monitoring, experience, evaluation Hungary, former DDR, Poland, Slowakia, Romania 2 Deterministic RAMs: based on a soil mechanical approach Germany, Sweden, Denmark, Romania, Spain, France (Netherlands) 3 RAM based on mass of agricultural machinery Italy
Empirical RAM (based on experience, Jones et al., 2003) This is a two-stage methodology to assess the vulnerability of subsoil to compaction: 1 Assessing the inherent susceptibility based on texture and packing density. 2 Combining this soil susceptibility with an index of climatic dryness/subsoil wetness, to determine the vulnerability class.
Texture classes EU soil map 100 10
VERY FINE
20
30
70
40
60
50
50
FINE
(2 60
40
70
30
MEDIUM FINE
MEDIUM
20 10
) µm 50
Pe rce nt CL AY (< 2
80
T SIL nt rce Pe
µm )
90
80 90
COARSE
0 10
10
20
30
40
50
60
70
80
90
0 10
Percent SAND (50 - 2000 µm)
Packing Density Determined in a soil pit (visual) OR PD = Db + 0.009C …………………………………(1) Where Db is the bulk density in t m-3 PD is the packing density in t m-3 C is the clay content (%, by weight)
low 1.75 t m-3.
Inherent susceptibility to compaction according to texture and packing density
Packing density t m
Texture Code
-3
Low
Medium
High
< 1.40
1.40 – 1.75
> 1.75
Texture Class 1
1
Coarse
VH
H
M
2
Medium
H
M
M
3
Medium fine
M(H)
M
L
4
Fine
M
L
L
5
Very fine
M
L
L
9
Organic
VH
H
Jones et al (2003) Susceptability (texture, packing density)
Vulnerability to compaction according to soil susceptibility and climate Class
Climate Zone
Perhumid
Humid A
SubB
humid
Dry
Subsoil
Usually wet,
Often wet,
Usually
Seasonally
Moisture state
always moist
usually
moist,
moist and dry
Mostly dry
moist, rarely
seasonally
dry
dry
Soil
PSMD mm
≤ 50
51 – 125
126 – 200
201 – 300
> 300
Susceptibility
FC Days
> 250
150 –
100 – 149
< 100
≤ 40
E (E)
V (E)
V (V)
M
250 1
2
VH
E (E)
H
V (E)
V (E)
M (V)
M (M)
N
M
V (E)
M (V)
N (M)
N (N)
N
L
M (V)
N (M)
N (N)
N (N)
N
Jones et al Vulnerability (susceptibility, climate)
Deterministic RAM (based on soil mechanical approach)
Determination precompression strength with uniaxial test
Pv
Precompression stress (pF 1.8), 30-60 cm soil depth for Germany (SIDASS-model)
Precompression stress classes: 1 Very Low < 30 kPa 2 Low 30 - 60 3 Mean 60 - 90 4 High 90 - 120 5 Very High 120 - 150
Compaction by compression and shear
Terra Tyre, sandy soil, wheel load 80 kN (8 tonnes)
Soil failure
2.5 17.5 32.5
62.5 Compaction by:
■ shear + compression ■ shear ■ compression
77.5 92.5 107.5 122.5
Distance (perpendicular to dirving direction) to centre (cm)
-145
-130
-115
-100
-85
-70
-55
-40
-25
-10
5
20
35
50
65
80
95
110
125
140
137.5
Depth (cm)
47.5
Wheel load carrying capacity
Wheel load carrying capacity is reached if: Exerted stresses (load, tyre width, inflation pressure) = Strength subsoil
Max wheel load (kN) - Terra Tyre - Subsoil
Empirical Ù Deterministic
Empirical RAM
Deterministic RAM
Texture, BD
Soil mechanical properties
Climate zones, percipitation, evapotranspiration
Wet or moist soil
Land use
-
Land use => wheel loads
Management
-
Wheel loads
Experience
-
Soil Properties
Climate
Resilience
Dutch Soil Database: BD upper subsoil
Dutch Soil Database: Frequency BD upper subsoil
Dutch Soil Database: Predicted subsoil overcompaction in 2010
Conclusions • • • • • • • •
All RAMs are not complete Empirical RAMs are limited to experiences in countries Empirical RAMs neglect wheel loads Deterministic RAMs are more universal and “scientific” Deterministic RAMs neglect impact on soil properties Deterministic RAMs neglect resilience Deterministic RAMs require soil mechanical properties Results RAMs are not always in agreement
• •
Subsoil compaction increases in the Netherlands Not in agreement with RAMs?
•
Further development of deterministic RAMs is the best option for harmonization
5
pF (log(-soil water suction))
4
3
2
1
0 32
36
40
44
Pore volume (%) PR too high
Rootable
Too w et, aeration too low Aeration limiting PR limiting
Too dry
Bad structured soil
Bad structured soil
48
Reduced infiltration capacity
ENVASSO INDICATORS KEY ISSUES
Density (bulk or packing density, total porosity)
Air Capacity Compaction and structural degradation
(air-filled pore volume at specific suction) Permeability (saturated hydraulic conductivity) Visual assessment of structure and testing Mechanical resistance (penetrometer resistance)
Vulnerability to Compaction (estimated Vulnerability to Compaction
Causes of Compaction
from texture, density, climate, land use) Drainage condition (wetness class) Soil strength (precompression strength) Ground pressure Soil management and tillage practice
Soil Properties Soil functions and sub-functions that are directly affected by soil compaction, and soil parameters as possible indicators (Lebert et al., 2003). Soil function Soil sub-function
Indicator Single Parameter
Indicator: Aggregated Parameter
Air regime - Air storage - Air flow
Air capacity Bulk density Air permeability O2-Diffusion
For all sub functions:
Water regime - Water storage - Water flow
Water storage Available water capacity Bulk density Water conductivity (saturated/unsaturated
Plant production - Rootability
Root length density Bulk density Penetration resistance
Visual classification of soil morphology by: - Effective bulk density - Packing density - Spade diagnosis
Soil Physical Threshold Values (1) Packings density PD PD = Db + 0.009C (g cm-3) Db = dry bulkdensity (g cm-3) C = clay content (weight %) Low Medium High
PD < 1,40 PD 1,40 - 1,75 PD > 1,75
Dry bulkdensity Db Db < 1.75 - 0.009C (g cm-3) Db < 1.6 (g cm-3 )
Soil Physical Threshold Values (2) Pore volume n n > 40% Air filled pores ng Bakker et al., (1987) Diffusion coëfficiënt Ds Never problems if Ds > 30 10-8 m2 s-1 Allways problems if Ds < 1.5 10-8 m2 s-1 Soil structure Very good Good Medium No, bad
Air filled pores ng : At least Desired >2% > 14 % >5% > 15 % >8% > 17 % > 12 % > 21 %
Soil Physical Threshold Values (3)
Hydraulic saturated conductivity Ksat Ksat > 10 (cm day-1)
Assessment: Packing density and bulk density ploughpan Dry bulk density (g/cm3)
2 1.8 1.6 1.4 1.2 1 0.8 0.6 0.4 0.2 0 0
20
40
60
Clay content (%)
80
100
Precompression stress, kPa
Climate
(Arvidson et al)
300
0.30 m
250 200 150 100 y = 40.655Ln(x) - 10.568 2 R = 0.9288
50 0 0
50
100
Tension (kPa)
150
200
Land use • •
•
Grassland Arable farming, - Ploughing - No-Till - Biological farming - Conservation Tillage Forest
• • •
Grains Root crops Silage maize
•
Heavy mechanization
Management
Sugarbeet harvesters 1999: Weight and wheel loads
Machine Gross vehicle weight (kN) Vehicle weight, empty (kN) Payload full tanker (kN) Wheel load full, left front (kN) Wheel load full, right front (kN) Wheel load full, left middle (kN) Wheel load full, right middle (kN) Wheel load full, left rear (kN) Wheel load full, right rear (kN)
Vervaet 17 382 226 156 114 114
77 77
Holmer Riecam Ropa Euro Terra Dos RBM 300-S Tiger 461 401 589 274 246 314 188 155 275 104 109 101 99 124 94 109 117 129 76 84 130 93 84
WKM Big Six 447 262 185 83 64 76 65 92 68
Kleine SF 40 518 285 233 75 73 93 79 92 107
Sugarbeet harvesters: Wheel loads and inflation pressures
Machine FRONT TIRES
Holmer Michelin
Agrifac Vervaet Michelin Trelleborg
make size 800/65R32 800/65R32
width (mm) Wheel load full, left front (kN) Wheel load full, right front (kN) measured infl. press., left (kPa) recommended infl. press., left (kPa) measured infl. press., right (kPa) recommended infl. press., right (kPa)
798 82 97 180 165 180 225
The recommended inflation pressure is for field use
798 95 90 180 220 170 200
850/60-38
850 120 106 210 280 190 225
WKM Michelin
Vredo Michelin
Riecam Tim Michelin GoodYear
11.2R36 750/65R26 800/65R32 800/65R32
284 26 26 260 400 250 400
754 76 74 190 205 190 200
798 120 96 190 300 200 225
819 99 90 180 235 170 200
Resilience: Persistence of subsoil compaction
(Alakukku et al)
L
L
120
L
L
L
4
5
S
L
Mean yield (%)
110 100 90 80 70 1
2
3
6
7
8
9
10 11 12 13 14 15 16 17
Years after compaction with wheel load of 50 kN Grain yield
Nitrogen yield
L = lodging S = sprouting Control =100 %
x
Database
criteria
CRITERIA Country Your Name Quest number RAM available? Soil typological unit Land use Equipment use
Germany Lebert
4B Y, I (STU) X e.g. LUCas X Weight, Wheel Load, Inflation Pressure , Tyre type W, WL, IP, W, WL, IP, Ty Ty Yes, Official, Development, Institute
e.g. Corine Land cover Digital elevation model Topography Pedotransfer functions
PTF + Texture OM Density Moisture
Drainage class Air
Germany Paul
Land Cover, Land Use, Spatial Soil Info
4A Y, I X
Field Capacity, Wilting Point, Water content sat, Workability Limit, Infiltration cap. sat
4C Y, I
4D Y, I
Poland Lopiec 5A Y, I
IP
X X GIS X
Bulkdensity dry, Bulkdensity at fc, Packing Density, Porosity, Degree of Compaction
Germany Germany Haider Marahrens
Bd, PD
Model + GIS X X Bd, PD
X
X
GIS
LC
X X Bd, PD
X X Bd, Bfc, Bd, PD DegComp FC, WP, FC, WP, Wsat, Ksat Wsat, Ksat
FC, WP, Ksat
FC, WP, Ksat, Infil_sat
FC
Acap
Acap, Diff
Acap
Acap, Acond
Acap, Acond, Diff
PreC, ShearS
PreC
PreC, ShearS
PreC
Pen
Ps, PEs
Py, Ps, Tj, Ts
Poland Denmark Greece Stuczyński Schjønning Papadopo ulos 5B 6A 12A Y, I Y, I No X X X X X W, WL, IP, W Ty X X X Model + GIS X X
Model + GIS X X
FC, WP, Wsat, WorkL, Ksat
FC, pFcurve
Italy Bazzoffi
Finland Alakukku
Hungary Birkás
Belgium Bielders
Belgium
18A Y, O
20A No
24A Y, I X X
25A No X X
25B Y, D X X
X
X
X W, WL, IP
X
LC, LU X X Bd, Bfc, Por FC, WP, Wsat
GIS + SSI X X
X X Bd, Bfc
Ksat
FC, WorkL, Ksat
X Air capacity, Air conductivity, Diffusion
Mechanical
PreCompression stress, Shear Strength, Penetration resistance
Climate
Precipitation, Temperature, Radiation, Potential Evapotranspiration, yearly, seasonal, monthly, 10 days, daily
Climate +
Land Cover, Land Use
Ps
LC
Acap
X X
X
X
X
Acond, Diff
Pen, PreC Pen, PreC Rd, Ped
GIS + Model
Pen Py, Pm, Tm, Ry, Rm, PEy, PEs LC, LU
Pen R10, PEs
Py, Ps, Pm, Pd, Ty, Ts
Py
Database
THRESHOLDS Country Quest number RAM available? Water content Saturated hydraulic conductivity Air capacity Oxygen diffusion rate
Thresholds
Germany 4A Y, I
Germany 4B Y, I
10 cm/d 5 vol%
10 cm/d 5 vol% 1
Germany 4C Y, I
Germany 4D Y, I 10cm/d 5 vol%
Poland 5A Y, I FC
Precompression stress Dry Bulk Density
> Load
> Load
X
Italy 18A Y, O
Finland 20A No
Hungary 24A Y, I
X
2,8-3,0 MPa
> Load
Klassen 4/ 5 (dicht/ sehr dicht) Klassen 4/ 5 (dicht/ sehr dicht)
Belgium 25A No
Belgium 25B Y, D
-1
1.4-1.5 Mg m-3
class 4 and 5 (DIN 19682-10, Germany)
Greece 12A No X
24 cm/d
2-3 Mpa
Bulk Density at Field Capacity
Packing Density
Denmark 6A Y, I
10 vol %
