compaction due to farm machinery

1. SOIL COMPACTIONDUE TO FARM
MAChINERY
Presentation
on
Presented By:
Pampaniya Nirav K.
M. Tech. Student. (SWE)

2.  During the last four decades, capital, chemical, and energy-intensive agriculture
has doubled farm production.
 Mechanization has reduced agricultural labor by a factor of three.
 The use of heavy machinery often leads to soil compaction, which in turn is
overcome by increasing inputs of energy, chemical fertilizers, and water. All of
these practices have a negative bearing on agricultural sustainability
(Upadhyaya, 1992).
Introduction

3.  Compaction of the soil is one of the major ways in which treatments
affect soil structure, and soil compaction problems plague agricultural,
horticultural and forest crop production everywhere in the world
 Soil covers a large proportion of the 149 million km2 global land area, but
only an estimated 93 million km2 are biologically productive containing
approximately 33 % forest, 32 % pastures and 11 % crop land (Sudduth et
al., 2014).

4.  Compaction is simply a reduction in pore space.
 Soil compaction occurs when soil particles are pressed together,
reducing pore space between them as shown in below fig.
Fig. Soil Compaction
What is soil compaction ?

5.  To characterize the state of compactness of a soil layer the
following are the most frequently used parameters.
 Bulk density
 Particle density
 Porosity
Bulk density:
 Bulk density defined as the ratio of the mass of soil particles to the total
volume of soil.
 The bulk density of a soil is always smaller than its particle density.
 The bulk density of sandy soil is about 1.6 g / cm3, whereas that of organic
matter is about 0.5 g / cm3.
 Bulk density normally decreases, as mineral soils become finer in texture.
 The bulk density varies indirectly with the total pore space present in the
soil and gives a good estimate of the porosity of the soil.

6. Bulk density of different textural classes
Textural class Bulk density (g/cc) Pore space (%)
Sandy soil 1.6 40
Loam 1.4 47
Silt loam 1.3 50
Clay 1.1 58
( ) s
b
t
M
Bulk density
V
 

7. Particle Density:
 The mass per unit volume of the solid portion of soil is called particle density.
 Generally particle density of normal soils is 2.65 g / cm3.
 The particle density is higher if large amount of heavy minerals such as
magnetite; limonite and hematite are present in the soil.
 With increase in organic matter of the soil the particle density decreases.
Particle density is also termed as true density.
 Bulk density
 Particle density
 Porosity

8. ( ) s
s
s
M
Partical density
V
 
Textural classes Particle density ( g / cm3)
Coarse sand 2.655
Fine sand 2.659
Silt 2.798
Clay 2.837
Partical density of different textural classes

10.  Bulk density
 Particle density
 Porosity
Porosity
 Porosity can be defined as the ratio of the volume of pores (voids) to the
total soil volume.
 Porosity is a measure of the void spaces in a material, and is a fraction of
the volume of voids over the total volume.
1 b
s
Porosity


 

11. What causes soil compaction?
 Soil compaction is caused when the applied stress, i.e. weight, exceeds the
strength of the soil.
 The stress depends on the weight of the vehicle and the contact area over
which the weight is distributed.
 The wheel-load carrying capacity of subsoil is the maximum stress that can
be exerted without exceeding soil strength.
 The use of agricultural machinery can lead to the compaction of both grazed
and silage fields, causing compaction of both surface (0.0 to 0.4 m) and
subsurface (> 0.4 m) soil.

12. Surface compaction
(<0.40m depth)
Subsurface compaction
(>0.40 m depth)
 Ground contact pressure  High axle loads
 Increased number of
wheelings/vehicle Passes
 Weight independent of the pressure
on the soil surface
 Number of vehicle passes
 Tyre inflation pressure
 Tyre width

13. Tillage operations –
 Continuous mouldboard ploughing or disking at the same depth will cause
serious tillage pans (compacted layers) just below the depth of tillage in
some soils.
 This tillage pan is generally relatively thin (1-2 inches thick), may not have a
significant effect on crop production, and can be alleviated by varying depth
of tillage over time or by special tillage operations.
Wheel traffic –
 This is without a doubt the major cause of soil compaction. The weight of
tractors has increased from less than 3 tons in the 1940's to
approximately 20 tons today for the big four-wheel-drive units.
 Traffic by farming vehicles and repeated cultivation by tillage implements
forces soil particles and aggregates closer together by compression
(downward pressure from farm machinery) and shearing/smearing
(spinning or slipping of wheels and the action of tillage implements
causing sideways force and realignment of the soil particles).

15. Factors in Vehicle Compaction
 Weak soil
• Moisture Content Effect
• Density Effect

16.  Excessive Loads
• Size of Load at the Surface – Ground Pressure
• Severity of Load at the Surface
• Impact at Depth
• For equal stress at the surface, larger tires affect soil to a greater depth
• Vehicles have gotten larger.

17.  Greater axle loads and wet soil
conditions increases the depth of
compaction in the soil profile.
Compaction caused by heavy axle
loads (greater than 10 tons per
axle) on wet soils can extend to
depths of two feet or more
axle loads
wet soil
Source: Soehne, 1958

18. Effects of Compaction:
 Soil’s Physical Properties
 The major impact of soil compaction is the alteration of soil’s physical
properties.
 The most notable changes are in soil bulk density, soil strength,
porosity, and hydraulic properties such as infiltration rate and
hydraulic conductivity.

20.  Vertical Water movement
 Compaction causes slower water movement through the soil in most
circumstances.
 Depending on soil type, the severity of compaction and the depth at
which it occurs, water may not drain readily through the root zone.
 Increase soil erosion
 Decreased Infiltration
Increase soil erosion Decreased Infiltration

21.  Slow and restricted root growth
 The major effect of compaction is an increase in bulk density as
soil aggregates are pressed closer together, resulting in a greater
mass per unit volume.
 Compaction reduces the soil pore volume, resulting in less space
for air and water in the soil.

22. Plant response to surface compaction
 The effect of compaction on plant growth and yield depends on
the crop grown and the environmental conditions that crop
encounters.
 In general, under dry conditions some compaction is beneficial,
but under wet conditions compaction decreases yields

23. Repeated action of cultivation equipment: PLOUGH PANS
 compacted layer just below
cultivated depth
• fine textured (clay) soil at highest
risk especially if cultivated when
Wet
• soil aggregate structure is broken
down and pores become sealed
• root penetration is restricted
• water penetration is restricted
• risk of waterlogging
• plant growth stunted
Source: Needham et al. 1998, Hunt and Gilkes 1992

24. Repeated traffic by wheeled vehicles: TRAFFIC PANS
• compacted layer 10–40 cm below
Surface
• sand to sandy loam soils at
highest risk
• wet soil is more susceptible
• root penetration is restricted
• water and nutrients penetrate
faster than roots
• risk of nutrient leaching
• poor use of subsoil water
• reduced production
Source: Needham et al. 1998, Hunt and Gilkes 1992

25. Case Study -1
Impact of Soil Compaction on Root
Length and Yield of Corn (Zea mays)
under Irrigated Condition

26. Introduction
Farm mechanization is a key element in the modern agricultural
activities the extensive use of heavy machinery in farming activities
brings about numerous benefits.
The use of farm machinery needs proper management otherwise
unnecessary and excessive use create soil management problem
and can adversely affect the plant growth.
Soil compaction is the main form of soil degradation which affects
11 % of the land area in the surveyed countries of the world.
Adverse effects of compaction include increased bulk density,
reduced porosity, restricted root growth, poor plant growth and
yield over 30 % of ground area is trafficked by the tyres of heavy
machinery even in genuine zero tillage systems one pass at sowing

27. In Pakistan the tillage operation by farmer are generally
performed with bullocks and tractor drawn cultivators to the
depth of 10 to 15 cm.
Repeated use of cultivator create a hard pan at about of 15
cm depth which hinders the movement of water and air and
inhibits growth of plant roots.
Maize is an important food crop which can be selected to
combat the problem of food shortage on Pakistan.
Keeping in view the speed of mechanization and the soil
compaction effects on crop growth, the present study was
aimed to find the effects of soil compaction on plant root
growth, bulk density and to explore some best and cheap
tillage machines to combat soil compaction.

28. MATERIALS AND METHODS
The field experiment was conducted during the year 2011 at the
Malakandher Farm Experimental Research Farm of KPK
Agricultural University Peshawar.
Corn variety Jalal was sown on June 25, 2011 there were 4
replications of each 3 tillage practices and 3 compaction passes
comprising to the total 9 treatments and 36 plots. Each plot was be
30 × 5 m2.
In the experiments the effects of soil compaction on maize crop
was studied, the soil was prepared by
 T1 = Cultivator once + Planking (Minimum Tillage).
 T2 = Cultivator (2) + Cultivator (2) (Conventional Tillage).
 T3 = M.B plow + Rotavator (Optimum Tillage)
 P0 = Control (no pass of tractor).
 P1 = 2 passes of Tractor + Planking
 P2 = 4 passes of Tractor + Planking.

29. Interaction of tillage practices(T) x Tractor passes (P) There
will be 9 treatments i.e.
 T1 =MTP0
 T2 =MTP1
 T3 =MTP2
 T4 =C2P0
 T5 =C2P1
 T6 =C2P2
 T7 =OPTP0
 T8 =OPTP1
 T9 =OPTP2

30. RESULTS AND DISCUSSION
 The soil having low bulk density has more porosity, good hydraulic conductivity, thus
having favourable condition for plant growth.
 The highest bulk density was observed in T3 i.e MTP2 which was 1.7 (g/cm3). The
lowest bulk density 1.54 (g/cm3) was reported in T7 as shown in Figure, this due to
the deep ploughing by mould board plough and rotavator which resulted in breaking
of hard pan, fine seed bed preparation, increased porosity and burying of previous
crop residues.
1.63
1.68
1.71
1.62
1.64
1.7
1.54
1.59
1.63
1.45
1.5
1.55
1.6
1.65
1.7
1.75
T1 T2 T3 T4 T5 T6 T7 T8 T9
bulkdensity(g/cm3)
Treatments
Figure : Effects of soil compaction on bulk density (g/cm3)

31.  Root Length: Root length was influenced by soil physical conditions like
bulk density and porosity as well as moisture availability.
 The maximum root length (20.9 cm) was exhibited by T7 which
progressively decreased to the minimum (11 cm) in T3 as indicated
following figure.
Figure : Effects of soil compaction on root length (cm)
13
11.6
10.8
14.1
12.1
10.9
20.9
17.2
16.4
0
5
10
15
20
25
T1 T2 T3 T4 T5 T6 T7 T8 T9
Rootlegth(cm)
Treatments
Root length (cm)
Root length (cm)

32.  Plant Height: Plant height is considered a genetic character which is
modified by environmental factors like availability of moisture and
nutrients at active growth stages.
 The maximum plant height of corn (210.5 cm) was found in T7 which
progressively decreased to the minimum and 185.5 cm in corn in T3 .
 Significant differences for plant height observed in compacted treatments
may be attributed to reduced ability of roots to penetrate in deep layers
for extraction of moisture and nutrients Therefore, growth and
development was retarded.
196
193.5
185.7
200.1
197.5
199.1
210.5
207.8
205.6
170
175
180
185
190
195
200
205
210
215
T1 T2 T3 T4 T5 T6 T7 T8 T9
Plantheight(cm)
Treatments
Plant height(cm)
Plant height(cm)
Figure : Effects of soil compaction on plant height (cm)

33.  Grain Yield: Grain yield was significantly affected by compaction
treatments. The maximum grain yield (4415.2 kg/ha) was exhibited
by T7 which progressively decreased to the minimum (2522.32
kg/ha) in T3 compacted plots of MTP2
 Treatment means showed significant differences for grain yield. The
control treatment was at par with T8 and T9 but significantly higher
than T3- Rest of the treatments from T1 T6 remained non-significant
to each other.
2595.75 2521.065 2522.32 2601.75 2542.1 2531.05
4415.2 4391.63
4156.45
0
500
1000
1500
2000
2500
3000
3500
4000
4500
5000
T1 T2 T3 T4 T5 T6 T7 T8 T9
Yield(kg/ha)
Treatments
Yield kg/ha
Yield kg/ha
Figure : Effects of soil compaction on grain yield (kg/ha)

34. Compaction has significant effects on bulk density root
length and grain yield. On average the field prepared by
mould board + rotavator with zero pass of Tractor
(OPTP0) having lower bulk density as compared to
compacted fields.
For good yield Mould board plough should be used on
silty clay loam soil that incorporate the crops residues
with soil, decreases bulk density and gave better yield
of maize. As compared to MTP0 as well as C2P0, which
are in practice by local farmers in the country.
CONCLUSSION

35. Case Study - 2
A simulation test of the impact on
soil moisture by agricultural
machinery

36. INTRODUCTION
 As agricultural machines become larger and heavier, there is a growing
concern about soil compaction owing to their intensive use which is a
serious issue for soil management throughout the world.
 Soil compaction is an important component of the land degradation
syndrome, which could influence soil properties such as pore size
distribution, soil moisture and density.
 soil compaction by agricultural machinery reduces soil moisture is
complex and ambiguous.
 Hence, in this study, they investigated the influence of compaction on
soil moisture by a simulated test method employing round iron plate
based on the ground pressure ratio between the front and rear wheels
of wheeled tractors and crawler tractors.

37. MATERIALS AND METHODS
Simulated pressure loads for the tractors
 Two commonly used tractors were introduced in this study:
Dong Fang Hong-75 crawler tractor with a weight of 5460
kg and Shanghai 50-wheeled tractor with a weight of 2020
kg. For the former, its local pressure ratio is about 38.3 kPa,
and the average pressure ratio can be calculated as 101
kPa.
 To simulate the pressure impacted on soil by the tractors, a
round iron plate with the diameter, height and weight by
11 cm * 5 cm * 4 kg and several weights with three
different masses of 30, 25 and 4 kg were used.

38.  The contact area of round iron plate was 95 cm2, and thus the loads
needed were approximately 37, 98, 118 and 196 kg for simulating the
local and average pressure ratio of Dong Fang Hong-75 crawler tractor
and the ground pressure ratios of the rear and front wheels of Shanghai
50-wheeled tractor.
 Thay took the combined soil compaction by both front and rear wheel
of Shanghai 50-wheeled tractor and set 314 kg as the extreme load
compacted on soil for their experiments.
 Considering the mass of round plate (4 kg), the configuration of weights
for pressure loads was set up as shown in Table 1. The compaction
simulation was conducted by adding the weights for a specific load on
the round iron plate
Table 1. The configuration for setting pressure loads with weights.
Weight type
(kg)
Quantity of weight required for setting pressure load
37 kg 98 kg 118 kg 196 kg 314 kg
30 0 3 2 6 8
25 1 0 2 0 2
4 2 1 1 3 5

39. Test field and treatments
On the experimental farm of Northwest A&F University
(108°4'15"E, 34°17'18"N), a flat fallow field with 2 m long and
1.5 m wide was chosen as the test field for this study.
Before the experiment, the field soil characterized as sandy
loam was loosened and watered artificially until the
compaction was about 200 N cm-3
The field characterized was divided into five zones for tests
with five pressure loads accordingly.
Before compaction, the soil moistures in each zone were
measured first at a selected point with 0 to 5, 5 to 10, 10 to
15, 15 to 20, 20 to 25, 25 to 30 and 30 to 35 cm depths.
They also pressed soil five times consecutively by the pressure
load of 314 kg and did experiments in the same way.

40. RESULTS AND DISCUSSION
 Soil moisture and its loss after compaction by pressure loads
 Soil moistures that resulted by the pressure loads varied from 12 to 17%
(Table ), which was caused mainly by the uneven nature of the soil and the
pre-treatment of loosing and watering soil.
Table . Soil moisture at different depths after compaction by pressure load
Depth(cm)
Soil moisture after compaction by pressure load (%)
37 kg
98 kg
118 kg 196 kg 314 kg
0 - 5 12.490 11.768 13.880 12.142 12.083
5 - 10 13.305 12.710 14.195 12.431 12.088
10 - 15 14.042 13.543 14.963 13.887 13.339
15 - 20 15.100 14.707 15.921 15.431 15.220
20 - 25 16.030 15.981 16.881 16.353 16.332
30 – 35 16.886 16.891 17.113 16.784 16.771

41.  The loss of soil moisture impacted by compaction with pressure load
 Generally, soil moisture lost after compaction, shown as the positive
moisture loss at the 0 to 5, 5 to 10, 10 to 15 and 15 to 20 cm depth after
compaction.
 The moisture losses at different depths increased first sharply and then
gradually as the increases of pressure load.
Table . Moisture loss of soil at different depths after compaction by pressure load.
Depth (cm)
Moisture loss after compaction by pressure load (%)
37 kg 98 kg 118 kg 196 kg 314 kg
0 - 5 0.208 0.930 1.023 1.885 1.944
5 - 10 0.138 0.733 1.116 2.097 2.440
10 - 15 0.042 0.541 0.820 1.209 1.757
15 - 20 -0.017 0.376 0.295 0.576 0.787
20 - 25 -0.002 0.047 0.016 0.050 0.071
30 - 35 0.013 0.008 0.003 0.007 0.020

42. Figure. Changes in moisture loss of soil at the same depth with pressure loads.

43.  Changes in the loss of soil moisture with depths by compaction
 Figure shows the curves of moisture loss changed with soil depths by
pressure loads. For light loads (37 and 98 kg), the moisture loss decreased
gradually and went to zero with the increases in soil depth.
 For heavy load (>= 118 kg), the moisture loss first increased with the
increases in soil depth but then quickly decreased to zero.
Figure . Changes in moisture loss of soil with depths by pressure loads.

44.  Changes in the loss of soil moisture with times of compaction
 The result of moisture loss by different compactions is shown in Figure. The
pattern of moisture loss by 5 compactions was close to that by 1 compaction, in
which the moisture loss first increased to a maximum value (2.45% for one
compaction and 3.48 % for 5 compactions at the depth close to 7.5 cm) and then
quickly decreased with the increase of soil depth.
Figure . Changes in moisture loss of soil with compaction times by 314 kg load.

45. Conclusion
 The simulated test results demonstrate that in general, after soil compaction
by agricultural machinery, soil moisture was partially lost from the soil.
 The moisture loss increased with the increases of the pressure load, and the
highest moisture loss occurred at the soil surface (0 to 5 cm) for light loads (<
110 kg), but at the depth of 5 to 10 cm for heavy loads (>110 kg), thus
indicating that the loss of soil moisture is not only related to pressure load.
 It was also observed that not in one way does the moisture loss change with
soil depth.
 Generally, more compaction resulted in more moisture loss. Also, the loss of
soil moisture by 5 compactions was in similar pattern with 1 compaction.
 Although much larger with the gap by 0.5 to 1.5 % between them for all the
observed depth. This therefore implies that the compaction and moisture loss
could be cumulative.

46. Final conclusion
 Compaction has significant effects on bulk density, root length and grain
yield.
 The effects of compaction on plant growth and yield depend on the crop
grown, soil type, and weather conditions
 Compaction on average the field prepared by mould board + rotavator with
zero pass of Tractor having lower bulk density as compared to compacted
fields.
 In general, after soil compaction by agricultural machinery, soil moisture
was partially lost from the soil.
 The moisture loss increased with the increases of the pressure load, and
the highest moisture loss occurred at the soil surface (0 to 5 cm) for light
loads (< 110 kg), but at the depth of 5 to 10 cm for heavy loads (>110 kg),
thus it was concluded that the loss of soil moisture is not only related to
pressure load.
 Excessive compaction decreases water infiltration and storage, decreases
root growth, reduces the soil volume explored by roots and can reduce
crop yields.

47. THANK
YOU

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