Directory UMM :Data Elmu:jurnal:S:Soil & Tillage Research:Vol56.Issue3-4.Aug2000:
Soil & Tillage Research 56 (2000) 117±129
Compaction of an Eutric Cambisol under heavy wheel traf®c
in Switzerland Ð ®eld data and modelling
M. Gysia,*, G. Klubertanzb, L. Vullietb
a
Swiss Federal Research Station for Agricultural Economics and Engineering (FAT), CH-8356 Taenikon, Switzerland
b
Swiss Federal Institute of Technology (EPFL), Soil Mechanics Laboratory, CH-1015 Lausanne, Switzerland
Received 16 September 1999; received in revised form 19 May 2000; accepted 2 June 2000
Abstract
Heavy agricultural machinery can cause structural degradation in agricultural subsoils. Severe structural degradation
impedes plant growth. Therefore, compaction must be limited to layers that can be structurally reclaimed and remoulded with
reasonable effort by tillage. The purpose of this study was to investigate the impact of a single pass with a sugar beet harvester
on the soil properties of an unploughed Eutric Cambisol. Field measurements and laboratory testing were carried out in
Frauenfeld, Switzerland. In addition 2D calculations of strain, stress and subsequent compaction were conducted using a
three-phase (soil skeleton, pore water, and air) model for unsaturated soil incorporating a recently developed constitutive law.
Model data were compared to the ®eld measurements. Due to the pass of the machinery, the soil was compacted down to a
depth of at least 0.15 m and at most 0.25 m. This compaction was indicated by an increase in soil bulk density and preconsolidation pressure as well as by a decrease in total porosity and macroporosity. The surface displacement measured in the
®eld was consistent with the calculated model data. The calculated and measured stresses at depths of 0.35 and 0.55 m stand in
good accordance with each other, whereas at a depth of 0.15 m the pressure measured in the ®eld exceeded the calculated
pressure. In this study, we show the degree of compaction due to heavy wheel traf®c and the suitability of a model approach to
describe compaction processes. # 2000 Elsevier Science B.V. All rights reserved.
Keywords: Compaction; Soil properties; Model; Laboratory; Field experiment; Eutric Cambisol; Switzerland
1. Introduction
In Swiss agriculture, economic pressure progressively favours the use of heavy machinery. The ever
increasing weight of machinery and the necessity to
work also under unfavourable conditions increase the
risk of soil compaction. Compaction may signi®cantly
impair the production capacity of a soil. HaÊkansson and
Reeder (1994) showed a crop yield loss of 14 per cent the
*
Corresponding author: Tel.: 41-52-368-3354;
fax: 41-52-365-1190.
E-mail address: [email protected] (M. Gysi).
®rst year after repeated wheel traf®c on agricultural soils
in seven different countries in Europe and North America. These effects may not immediately become evident.
According to Moullart (1998), soil compaction can
impede root growth; however, the above-ground parts
of the plants often do not show reduced dry matter
production. Compaction reduces the penetrability of
the soil for roots (Unger and Kaspar, 1994). In nutritional
de®ciency situations, changes in the soil pore volume
may reduce water and nutrient supply of the root.
Furthermore, soil organisms depending on oxygen
may be affected. Horn et al. (1995) observed an increase
of N2O, CH4 and CO2 emissions in compacted soils.
0167-1987/00/$ ± see front matter # 2000 Elsevier Science B.V. All rights reserved.
PII: S 0 1 6 7 - 1 9 8 7 ( 0 0 ) 0 0 1 3 2 - X
118
M. Gysi et al. / Soil & Tillage Research 56 (2000) 117±129
Topsoil compaction is not considered to be a serious
problem because the regeneration potential of the soil
structure is relatively high due to biological (below
ground animals, plant roots), climatic (dehydration and
frost) and anthropogenic (soil tillage, cultivation) in¯uences. In the subsoil these factors are less effective and
structural recovery is therefore less intense. The effect of
subsequent subsoil compaction is to be considered
cumulative (Semmel et al., 1993). In addition, technical
measures taken in order to loosen the subsoil are expensive and their bene®ts are often controversial.
Subsoil compaction can be predicted by the means
of ®nite element model (FEM). To simulate compaction under tyres, non-linear elastic (Perumpral et al.,
1971; Pollock et al., 1986; Chi et al., 1993), plasticity
(Chung and Lee, 1975; Kirby, 1989a) and critical state
(Kirby, 1989b) models have been used.
In this paper, we calculate compaction under a tyre
using a fully coupled three phase approach recently
developed by Klubertanz (1999) and implementing
the new constitutive law of Geiser (1999) for unsaturated soil behaviour. Further on, we present the results
of a compaction experiment carried out in Switzerland. A sugar beet harvester was used for the experimental treatment which took place in October, 1998.
A full set of soil mechanical and soil physical parameters were measured in the plot subjected to wheel
traf®c and in an untraf®cked plot nearby. Some of
these parameters served as input variables for the
model. The output of the model is compared to data
recorded during the ®eld experiment.
2. Material and methods
2.1. Experimental design and machine properties
The experimental area is located near Frauenfeld
(Swiss National Coordinates: 270 000/707 950, topo-
graphical map sheet 1053: Frauenfeld). The soil,
situated on a wide valley bottom, is a skeleton-free
Eutric Cambisol. The organic C content varies
between 510ÿ3 and 0.510ÿ3 kg kgÿ1. The texture
of the samples taken at a depth of 0.12±0.17 and 0.32±
0.37 m, is a sandy loam; at a depth of 0.52±0.57 m
texture is a loamy sand (Table 1).
The year prior to the ®eld experiment, winter wheat
(Triticum spp.) was grown at the experimental site and
harvested with a plot combined harvester. During the
last 10 years, the farmer practised a soil preserving
cultivation method without ploughing. No plough pan
was found with the penetrometer.
The plot was subjected to a single pass with the right
front wheel of a self-propelled six-row sugar beet
(Beta vulgaris L.) harvester, model Kleine SF10 in
October, 1998. Driving speed was 1 m sÿ1. The lifting
units of the combine harvester were raised. A Goodyear radial tyre 710/70 R 38 was used. This 0.68 m
wide tyre had an in¯ation pressure of 220 kPa. The
total weight of the sugar beet harvester was 285.2 kN.
Total load is unevenly distributed onto the four wheels
due to the raising of the lifting units as well as to the
laterally extended unloading elevator. The highest
load (107 kN) is applied to the right front wheel.
In order to determine the contact area, the tyre print
was marked with lime powder, subsequently photographed and the contact area determined by digital
image processing. This yielded a value of the contact
area of 0.71 m2. The average ground contact pressure
was thus 151 kPa as summarised in Table 2. An
untraf®cked plot next to the treated plot served as
control area.
Both plots were at all times exposed to natural
precipitation. This resulted in a matric potential of
ÿ26 hPa and a volumetric soil water content of 24% at
a depth of 0.12±0.17 m (Fig. 1). At the time of the
experiment the ground water level was at a depth of
1 m.
Table 1
Soil organic C content and texture of Eutric Cambisol in the test area in Frauenfeld, Switzerland
Depth (m)
Organic C content
(kg kgÿ1)
Clay
Compaction of an Eutric Cambisol under heavy wheel traf®c
in Switzerland Ð ®eld data and modelling
M. Gysia,*, G. Klubertanzb, L. Vullietb
a
Swiss Federal Research Station for Agricultural Economics and Engineering (FAT), CH-8356 Taenikon, Switzerland
b
Swiss Federal Institute of Technology (EPFL), Soil Mechanics Laboratory, CH-1015 Lausanne, Switzerland
Received 16 September 1999; received in revised form 19 May 2000; accepted 2 June 2000
Abstract
Heavy agricultural machinery can cause structural degradation in agricultural subsoils. Severe structural degradation
impedes plant growth. Therefore, compaction must be limited to layers that can be structurally reclaimed and remoulded with
reasonable effort by tillage. The purpose of this study was to investigate the impact of a single pass with a sugar beet harvester
on the soil properties of an unploughed Eutric Cambisol. Field measurements and laboratory testing were carried out in
Frauenfeld, Switzerland. In addition 2D calculations of strain, stress and subsequent compaction were conducted using a
three-phase (soil skeleton, pore water, and air) model for unsaturated soil incorporating a recently developed constitutive law.
Model data were compared to the ®eld measurements. Due to the pass of the machinery, the soil was compacted down to a
depth of at least 0.15 m and at most 0.25 m. This compaction was indicated by an increase in soil bulk density and preconsolidation pressure as well as by a decrease in total porosity and macroporosity. The surface displacement measured in the
®eld was consistent with the calculated model data. The calculated and measured stresses at depths of 0.35 and 0.55 m stand in
good accordance with each other, whereas at a depth of 0.15 m the pressure measured in the ®eld exceeded the calculated
pressure. In this study, we show the degree of compaction due to heavy wheel traf®c and the suitability of a model approach to
describe compaction processes. # 2000 Elsevier Science B.V. All rights reserved.
Keywords: Compaction; Soil properties; Model; Laboratory; Field experiment; Eutric Cambisol; Switzerland
1. Introduction
In Swiss agriculture, economic pressure progressively favours the use of heavy machinery. The ever
increasing weight of machinery and the necessity to
work also under unfavourable conditions increase the
risk of soil compaction. Compaction may signi®cantly
impair the production capacity of a soil. HaÊkansson and
Reeder (1994) showed a crop yield loss of 14 per cent the
*
Corresponding author: Tel.: 41-52-368-3354;
fax: 41-52-365-1190.
E-mail address: [email protected] (M. Gysi).
®rst year after repeated wheel traf®c on agricultural soils
in seven different countries in Europe and North America. These effects may not immediately become evident.
According to Moullart (1998), soil compaction can
impede root growth; however, the above-ground parts
of the plants often do not show reduced dry matter
production. Compaction reduces the penetrability of
the soil for roots (Unger and Kaspar, 1994). In nutritional
de®ciency situations, changes in the soil pore volume
may reduce water and nutrient supply of the root.
Furthermore, soil organisms depending on oxygen
may be affected. Horn et al. (1995) observed an increase
of N2O, CH4 and CO2 emissions in compacted soils.
0167-1987/00/$ ± see front matter # 2000 Elsevier Science B.V. All rights reserved.
PII: S 0 1 6 7 - 1 9 8 7 ( 0 0 ) 0 0 1 3 2 - X
118
M. Gysi et al. / Soil & Tillage Research 56 (2000) 117±129
Topsoil compaction is not considered to be a serious
problem because the regeneration potential of the soil
structure is relatively high due to biological (below
ground animals, plant roots), climatic (dehydration and
frost) and anthropogenic (soil tillage, cultivation) in¯uences. In the subsoil these factors are less effective and
structural recovery is therefore less intense. The effect of
subsequent subsoil compaction is to be considered
cumulative (Semmel et al., 1993). In addition, technical
measures taken in order to loosen the subsoil are expensive and their bene®ts are often controversial.
Subsoil compaction can be predicted by the means
of ®nite element model (FEM). To simulate compaction under tyres, non-linear elastic (Perumpral et al.,
1971; Pollock et al., 1986; Chi et al., 1993), plasticity
(Chung and Lee, 1975; Kirby, 1989a) and critical state
(Kirby, 1989b) models have been used.
In this paper, we calculate compaction under a tyre
using a fully coupled three phase approach recently
developed by Klubertanz (1999) and implementing
the new constitutive law of Geiser (1999) for unsaturated soil behaviour. Further on, we present the results
of a compaction experiment carried out in Switzerland. A sugar beet harvester was used for the experimental treatment which took place in October, 1998.
A full set of soil mechanical and soil physical parameters were measured in the plot subjected to wheel
traf®c and in an untraf®cked plot nearby. Some of
these parameters served as input variables for the
model. The output of the model is compared to data
recorded during the ®eld experiment.
2. Material and methods
2.1. Experimental design and machine properties
The experimental area is located near Frauenfeld
(Swiss National Coordinates: 270 000/707 950, topo-
graphical map sheet 1053: Frauenfeld). The soil,
situated on a wide valley bottom, is a skeleton-free
Eutric Cambisol. The organic C content varies
between 510ÿ3 and 0.510ÿ3 kg kgÿ1. The texture
of the samples taken at a depth of 0.12±0.17 and 0.32±
0.37 m, is a sandy loam; at a depth of 0.52±0.57 m
texture is a loamy sand (Table 1).
The year prior to the ®eld experiment, winter wheat
(Triticum spp.) was grown at the experimental site and
harvested with a plot combined harvester. During the
last 10 years, the farmer practised a soil preserving
cultivation method without ploughing. No plough pan
was found with the penetrometer.
The plot was subjected to a single pass with the right
front wheel of a self-propelled six-row sugar beet
(Beta vulgaris L.) harvester, model Kleine SF10 in
October, 1998. Driving speed was 1 m sÿ1. The lifting
units of the combine harvester were raised. A Goodyear radial tyre 710/70 R 38 was used. This 0.68 m
wide tyre had an in¯ation pressure of 220 kPa. The
total weight of the sugar beet harvester was 285.2 kN.
Total load is unevenly distributed onto the four wheels
due to the raising of the lifting units as well as to the
laterally extended unloading elevator. The highest
load (107 kN) is applied to the right front wheel.
In order to determine the contact area, the tyre print
was marked with lime powder, subsequently photographed and the contact area determined by digital
image processing. This yielded a value of the contact
area of 0.71 m2. The average ground contact pressure
was thus 151 kPa as summarised in Table 2. An
untraf®cked plot next to the treated plot served as
control area.
Both plots were at all times exposed to natural
precipitation. This resulted in a matric potential of
ÿ26 hPa and a volumetric soil water content of 24% at
a depth of 0.12±0.17 m (Fig. 1). At the time of the
experiment the ground water level was at a depth of
1 m.
Table 1
Soil organic C content and texture of Eutric Cambisol in the test area in Frauenfeld, Switzerland
Depth (m)
Organic C content
(kg kgÿ1)
Clay