DEVELOPMENT OF NEW METHODS TO DETERMINE THE RELATIONSHIPS
BETWEEN THE DRAFT REQUIREMENT, AND THE FUNDAMENTAL FACTORS
AFFECTING THE DRAFT REQUIREMENTS, OF TILLAGE TOOLS

By
Baba-Telischi

AN ABSTRACT

Submitted to the School of Graduate Studies of Michigan
State College of Agriculture and Applied Science
in partial fulfillment of the requirements
for the degree of
DOCTOR OF PHILOSOPHY
Department of Agricultural Engineering
Year
Approved b y

1954^

ProQuest Number: 10008439

All rights reserved
INFORMATION TO ALL USERS
The quality of this reproduction is dependent upon the quality of the copy submitted.
In the unlikely event that the author did not send a complete manuscript
and there are missing pages, these will be noted. Also, if material had to be removed,
a note will indicate the deletion.

uest
ProQuest 10008439
Published by ProQuest LLC (2016). Copyright of the Dissertation is held by the Author.
All rights reserved.
This work is protected against unauthorized copying under Title 17, United States Code
Microform Edition © ProQuest LLC.
ProQuest LLC.
789 East Eisenhower Parkway
P.O. Box 1346
Ann Arbor, Ml 48106-1346

uaba-Telischi

The problem of tillage is one of the most basic of
agricultural problems.

From the early days when, a piece of

crooked wood was pulled in the ground to prepare seed beds,
until now, when big steel plow's stir and turn the soil many
inches deep and wide, the question of ’’how to till the soil
at the best and most economical time” has existed.
Many scientists and engineers have studied this problem
and have reached some very interesting conclusions; more
work needs to be done to be able to obtain adequate information
at least to answer some basic questions on this subject.

The

problem of the force of soil resistance to the various imple­
ments of tillage and the factors that affect this force of re­
sistance will be the phase of tillage discussed here.
The investigation in the field of tillage is being done
mostly in two associated fields:

soil science and agricul­

tural engineering.
In soil science, soil physicists did basic work on
soil characteristics and their effect on tillage operation.
Agricultural engineers attempted to build different measuring
devices either for laboratory or field work to evaluate those
effects .
The work of the author consists mostly of the introduction
of new experimental and theoretical methods to indicate the
relationship between different factors and the draft require­
ment of tillage tools.

bave-iel?rehi

A preliminary field test was run in three dliferent
kinds of soils with five different tilling methods.

The

laboratory method consisted of running different tests in
a soil box under controlled conditions,

for the theoretical

method, the theory of dimensional analysis was employed.
The field tests were considered insufficient and inac­
curate to measure the draft requirement of tillage tools.
The results obtained from the laboratory method, though
qualitative, were very useful and encouraged the continua­
tion of the investigation.

The theoretical method was the

best way to obtain the basic relationships between the draft
requirement and the factors that affect the required draft.

DEVELOPMENT OF NEW METHODS TO DETERMINE THE RELATIONSHIPS
BETWEEN THE DRAIT REQUIREMENT, AND THE FUNDAMENTAL FACTORS
AFFECTING THE DRAFT REQUIREMENTS, OF TILLAGE TOOLS

By
Baba-Telischi

A THESIS

Submitted to the School of Graduate Studies of Michigan
State College of Agriculture and Applied Science
in partial fulfillment of the requirements
for the degree of
DOCTOR OF PHILOSOPHY
Department of Agricultural Engineering

1951)-

ACKNOWLEDGMENT
The author acknowledges the help and guidance of Professor
Howard F. McColly, under whom this project was conducted.

He

also expresses his thanks to Dr. A. Earl Erickson, Soil Science
Department, for his sincere cooperation and help in using the
Soil Physics laboratory for all the soil tests.
The author is grateful to Dr. Charles 0. Harris, head of
the Department of Applied Mechanics, for his help in setting
up the equation of the dimensiopless products for the theoreti­
cal solution.
Sincere thanks are due to the following for their assis­
tance and useful suggestions in different phases of the pro­
ject:
Professor Arthur W. Farrall, head of the Agricultural
Engineering Department;
Dr. Walter M. Carleton of the Agricultural Engineering
Department;
Dr. Holland T; Hinkle, Mechanical Engineering
Department; and
Mr. James B. Cawood, Research Laboratory, Agricultural
Engineering Department.
The author also wishes, to extend his appreciation to other
members of the Agricultural Engineering, the Civil Engineering,
and the College Farms departments, who helped in accomplishing
the field and laboratory experiments.

TABLE OF CONTENTS

Page
I.

INTRODUCTION

................................

1

. . ............................

1
1

A.

General

B.

The Effects of Tillage

..................

C.

The Objects of Tillage

. . .......

D.

Energy Analysis of Tillage

E.

Some Physical Properties of S o i l ........

5

1) T e x t u r e ................................

5

2) S t r u c t u r e ..............................

6

3

.............

3) C o n s i s t e n c y ...........................
a) Atterherg's Constants

IV.

b) Cohesion

...........................

8

c) Adhesion

.................. ,........

8

REVIEW OF LITERATURE

...

8

..........................

10

A.

The Work of Agricultural Engineers . . . .

B.

The Cooperative Work of SoilPhysicists

10
and

.................

17

OBJECTIVES

32

GENERAL INVESTIGATION OF THE P R O B L E M .........

33

A.
V.

6

7

Agricultural Engineers
III.

•

. . . . . . . .

d) Plasticity and Its Significance
II

ij.

Factors That Affect The Draft

........

33

METHODS OF P R O C E D U R E ..........................

37

Table of Contents

(Cont.)

Page
A.

..............................

37

1) Field T e s t s ............................

37

Field Work

if7

2) Results and C o n c l u s i o n s ...................
B.

Laboratory M e t h o d ...................

if9

1) Objective of the E x p e r i m e n t ...............
2) Soil B o x ................................

50

3) Tools and E q u i p m e n t ...................

5if

if) Soil

61

5) Test Procedure

C.

if9

................

62

6 ) R e s u l t s ................................

62

7) C o n c l u s i o n s .................

75

a)

The effect of speed

..............

75

b)

The effect of clay c o n t e n t ........

80

c)

Effect of m o i s t u r e ................

88

d)

Effect of packing force

..........

9k

.......................

95

1) Reasons for S t u d y .....................

95

2) General Remarks on Dimensional Analysis.

95

Theoretical Study

3) Assumptions and the Solution of the
97

p r o b l e m ..............
if) C o n c l u s i o n s ...............................
VI.

VII.

100

SUMMARY
SUGGESTIONS FOR FURTHER STUDY
A.

Changes in Laboratory Tests

...............
................

103
103

Table of Contents

(Cont.)

Page
1) Proposed Changes in Building Experimental
Soil B o x ...........................
2) More Tests With Different Conditions . . .
B.

More Theoretical

Study

................

C.

Application of Theoretical and Laboratory
Results to Field C o n d i t i o n s ................

VIII.

REFERENCES

103
10if
10if

10if
137

LIST OF TABLES
Table

Page

I,

The result

II.

The result
soil

.

of preliminary field t e s t s .............. if3
of field

tests (long strips) in sandy

....................................................ifif

III.

The result

of field

tests (long strips) in clay soil.

IV.

The result

of field

tests (long strips) in sod soil

V.

Some physical properties of experimental soils used
for the laboratory tests
..........................6if

VI - XXX.
XXXI.

• if6

The result of laboratory t e s t s ................ 106

The friction determination of the tool carrier in
the soil box...... .................................... 1 3 1

LIST OF FIGURES
Figure

Page

1.

Relationship between cohesion and colloidal content .

21

2.

Relationship between compression and colloidal
c o n t e n t ........ . ..................................

21

Relationship between maximum force of adhesion and
..............................
colloidal content
.

21

Relationship between lower plastic limit and the
activity of soil moisture
. . . . . ..............

23

Relationship between colloidal content of soil and
plasticity n u m b e r ..................................

2 if

Relationship between the metal friction and percent
of soil moisture
......................... ..

2 If

Reaction of soil as a plow advances through it

29

3*
if.
5.
6.
7.

...

8 . Dynamometer for field tests....... ...................

IfO

9.

Ifl

10.

Field test with two-bottom, lif-inch p l o w ............
A sample of dynamometer graph

........ ..

.

.

If2

11.

Soil box, the general v i e w ....................... ..

56

12.

Soil box, grading aid packing

..................

57

13.

Soil box, the moving section

..............

58

lif.

Tools and implements used in soil box experiment

15*

Attachment to the soil box to measure the friction of
the tool carrier
...........

60

Moisture release curve for the experimental soils

63

l6 .
17 -

25 • The curves of speed versus

26 -

29. The curves of clay percent

30 -

3 6 . The curves of moisture percent versusdraft

.

.

. .

draft... .............

59

66
76

versus draft . . . .
. .

81

List of Figures

(Cont.)

Page
37 - i+1•

The curves of packing forces versus draft . .

89

if2 - if6 .

The drawings of the soil b o x ................ 132

INTRODUCTION
General
Tillage refers to all the mechanical operations and
practices on the top layer of soil which are necessary to
provide a favorable seed bed.

In general, a good tillage

practice always improves the yield of the crop although
there are certain crop and soil conditions that cause the
tilling action to be somewhat unimportant.
Despite the improvement of the shape, material, and
the operation of tillage tools in recent years, the tillage
operation continues to consume a large percentage of farm
power.

Statistics show (74) that field operations constitute

about 4 8 percent of farm draft wrork, and that tillage work
makes up approximately 58 percent of field work (or 29 per­
cent of the total).

Over half of the power consumed in

tillage work is used in the basic operations of plowing
and disking (5 )*

So, ar*y improvement in the method of

tillage is a big contribution to the power requirement in
farming.
The Effects of Tillage
Tillage results in the change of structure by changing
the arrangement of secondary particles, conservation of
moisture, and control of weeds.

The main duty of tillage is the building of a structure
profile.

«J. A. Slypher (71) describes the specification of

this structure profile as model profile.

A vertically gradu­

ated structure and consistency is needed, the lower zone to
consist of fine granules and the firmest degree of consistency.
In successively higher zones, granulation should coarsen while
the consistency loosens.

The whole is to be topped by dis­

tinctly coarse granules forming a loose layer immediately
above the seed level.

Added organic matter to be intermixed

with the lower half to two-thirds of the plow layer.
"The old order consisted of a thin veneering of dust
on the surface, produced by overworking and reducing to a
structureless condition.

Beneath this and extending to the

subsoil, the mass remained crude and undisturbed.

A dust

veneer is a barrier to ready intake of rainfall, an encourage­
ment to evaporation, and fatal to ultimate good tilth.

The

new order would supplant dust with clods on the surface; and
within limits clods are useful.

The size of surface clods

is necessarily subject to limitation, as it depends on the
kind of crops and soils."
Slypher then suggests that a standard should be estab­
lished by experiment and explains:

"Since the object is to

fully structuralize the full plow layer, the design of tillage
tools should be changed to produce the above mentioned model
profile.

The problem is not the deep or shallow tilling, it

is rather, the manner of manipulation.

However, before the

design of tillage tools, the soil technologist must first
establish experimentally the standard profile.

Equally

important is the necessity of a measuring-sticlc for
structure applicable to field use."
Slypher finally discusses the particular cases of plow
actions with different soil conditions as:

"Old plows were

compressing unduly the soil but gradually it is changing to
cutting and lifting action.
that.

Type of soil has effect on

Sandy soils should receive more compression and less

lifting, because they don't have good structure and should
be left in contact with subsoil."
The Objects of Tillage
Until rather recently all soil manipulations have been
performed without knowledge of the effect of these manipula­
tions upon soil physics and plants.

On this basis the design

of implements were based entirely on the empirical results;
and practical experience was the main source of knowledge to
the selection of tillage tools and the. degree of tillage
practice.
In 1730 Jethro Tull, an English farmer explained that
the effect of tillage is only the breaking down of large soil
particles into the fine ones which increase the particle's
surface from which plant roots obtain their food.

(/;0 ) .

Today there is a need for a more adequate concept, and
the concept of Tull is not satisfactory anymore.

The modern approach to the problem of soil tillage is
by two methods ( 7 7 1 ) .

One involves an approach based

■upon fundamental physical laws, while the second calls for
an analysis involving the application and measurement of
both physical and biological phenomena.

It should be men­

tioned that the biological objective of the soil is different
for different crops, and each type of soil has a special mechan­
ism peculiar to itself.
Of these two approaches, the first one is probably the
more attractive to .engineers.
volves less variables.

It is simpler because it in­

The second method needs the coopera­

tion of physical and biological science.
Energy Analysis of Tillage
The approach of tillage problems through the physical
method must be based upon energy input in the field.

The

operations should be evaluated primarily on that energy
basis and the results should be correlated with the yield of
crops.

This involves three groups of variables, namely,

1)

The energy input in the operation;

2)

The character of the field operationsincluding

types of equipment;
3)

The economic relationship.

The efficient application of energy to any operation is
an engineering problem, and the amount of the applied energy
is directly related to the physical condition of the soil,

the kind and the condition of implement, and finally, the
management.

In this research we are concerned with the

first two, especially the physical condition of the soil.
Some Physical Properties of Soil
There are many factors which.could be mentioned in con­
nection with the physical properties of soil.

Only those

properties which are essential in the problem of tillage will
be discussed in this section.

Those properties are:

texture

structure, and soil consistency.
Texture
Texture refers to the size of individual primary par­
ticles which constitute the soil mass.

These particles have

been classified according to their sizes.
ticles are called clay.

The finest par­

The next larger are silt, then sand,

and the largest is gravel.
Any particle larger than 2 m. m. is called gravel.

The

particles between 2 m. m. and .02 m. m. (according to Atterberg's classification) are sand, between . 0 2 and , 0 0 2 is
silt, and any particle smaller than .0 0 2 m. m. is clay.
Gravel, sand, and silt build the frame of soil body, and
clay and silt, especially clay, will act as binding materials
The large surface area per unit mass of clay is responsible
for its activity chemically and physically.

Clay and organic

matter are the most active portions of the soil.

Structure
Bauer says (29) that the structure of a soil is the
arrangement of its particles.

These particles can be pri­

mary particles like sand, silt, clay, or they can be aggre­
gates that have formed from groups of primary particles..
Thus there are p r i m a r y and secondary particles and their
arrangements in the structural make-up of the soil.
Mechanical m a n i pul at ion changes the structural
of the surface layer of soil.

condition

Most of these manipulative

operations are designed to break up the large secondary
particles

into smaller ones, and also rearrange the secondary^

particles

to a more porous mass whi ch may settle or com­

pletely disintegrate on wetting,
of the secondary particles.

depending on the stability

The amount of man ip ula tio n

varies w i t h the kind of soil.

It is also possible to des­

t roy the original granulation

of the soil by too m u c h m a n i p u ­

lation.

Consistency
Soil consistency is a term used to designate the m a n i ­
festations of the physical forces of cohesion and a dhesion
acting within the soil at various moisture c o n t e n t s .
manifesta ti ons

include the beha vio r toward gravity,

These

pressure,

thrust, pull and the tendency of the soil mass to adhere to
f o rei gn bodies or substances and

denced by feel of the fingers

the sensstions w h i ch are evi­

of the pbserver.

s istency of soil varies w i t h the texture,

(71).

Con­

structure of the

soil and e specially w i t h the colloidal and moisture.
clay m i g h t f lo w easily if eno ug h moisture existed.

The
By d e ­

cre asi ng the moistu re content it w ill become sticky, and as
wat er continues to evaporate it becomes more sticky and
tough.

Vv’h e n it becomes air dry,

the clay will be harsh to

the touch, a nd finally, w h e n it is oven-dried,

it will reach

its m a x i m u m hardness.
Atter ber g' s C o n s t a n t s .

Lower and upper plastic limits,

an d p l a s t i c i t y number are called the A t t e r b e r g ’s constants.
Uppe r plastic limit
m o isture content,

(or liquid limit)

of a soil is that

expressed as a percentage of the weight of

the o ven -dr ie d soil,

at w h i c h the soil will

just begin to

f l ow w h e n lightly jarred ten times.
Lower plastic limit of a soil is the lowest moisture
content,

exp ressed as a percentage of the weight of the oven-

dried soil,

at wh i c h the soil can be rol le d into threads

on e - e i g h t h inch in diameter without the threads b reaking into
pieces .
Plasticity number is the difference b e t w e e n the above
moisture limits.
W i t h some m o is tu re less

than plastic range,

soft and w i t h very low moisture,

soil is harsh.

the soil is
There is a

f ourth f orm of consistency w h i c h might overlap the plastic
consistency.

This

is the sticky form.

forms of soil are then:

sticky,

The four consistency

plastic,

soft,

and harsh.

The extent of each f or m of consistency in a soil depends on

its kind.
number.
colloidal

A loamy soil might have a very small plasti ci ty
A clay soil,
content,

Cohesion.

according to the kind and amount of

can have a large p l ast ici ty nu mbe r

Cohes io n in a moist soil is attributed in a

lar^e degree to the surface

tension,

forces w h ich arise from

the water films di stributed through the soil mass.
Adhesion.

When the moisture content of soil exceeds

that for m a x i m u m cohesion,

the adhesion of the soil to

f o r e i g n material will take place.

At a h ig h moisture p e r ­

centage the water f i l m is held less tightly by the particles,
and will be attracted to the surface of the foreign objects.
This f i lm of water will connect the soil to the object.
Nichols has

indicated the force of a dhesion of colloidals

w i t h different amounts

(51+) of colloid content,

that their rel a t i o n is a linear function.
for any percent of colloids

and observed

He also found that

in the soil the moisture percentage

n e e d e d for m a x i m u m ad hesion is larger than the one for m axi mu m
cohesion.

The curves of b o t h adhesion and cohesion w ith r e ­

spect to moisture percentage are S-shaped and the one for ad­
h e s i o n is slightly higher than the one for cohesion.
Plasticity and its s i g n i f i c a n c e .

Atterberg studied the

p l a s t i c i t y f r om the point of view of the moisture range and
for the first time suggested the use of upper and lower p la s­
ticity limits and plast ici ty number.

Apparently,

he conducted

his original w or k w it h the hope of finding some physical cri­
t erion for the classific at ion of Swedish soil.

Terzaghi

(if)

has also suggestod that the plasticity limits may serve as
an index i'or the physical classification of soils.

Soil

with high upper plastic limit has either a high percent of
fine-grain fraction or is rich in plate-shape particles.
Soil having a high upper plastic limit and a low plasticity
number should be in a finely divided state.

A high plasticity

number shows a sign of having a large quantity of scale-like
particles.

Terzaghi (l|) has related the lower plasticity

limit to the permeability of clays and the rate of evaporation
of water films from soils.

He states that the coefficient of

permeability of a homogenous clay decreases rapidly with de­
creasing water content until, at lower plastic limit, it
becomes practically zero, regardless of the value of the plas­
tic limit.

He also states that the rate at which water evap­

orates from the surface of a clay sample is four percent greater
than the free water surface, provided the moisture content is
higher than the lower plastic limit.

We hr (i|) has reported

that cultivating a soil with a moisture content above the
lower plasticity number will cause puddling of the soil.
The small plasticity number indicates the ease of tilth
without puddling.

If this number is large, a danger of pud­

dling exists when cultivated above the lower plasticity limit.
Although there exists some relationship between these con­
stants and the soil tilth, sufficient evidence does not exist
to draw a more specific conclusion.

REVIEW OF LITERATURE
The study of draft requirement of tillage implements
and the factors that have an effect on the draft started
long ago.

Although different investigators have worked on

this problem under different soil conditions, until rather
recently there was very little basic research done.

Most

of the early investigators confined their studies to their
local soil conditions.
The study of force and energy measurement in tillage
can be divided into two sections:

the work of agricultural

engineers, and the cooperative work of agricultural engineer
and soil physicists.
The Work of Agricultural Engineers
The work done by engineers consists of studies of the
forces exerted by different tillage tools, design and de­
velopment of instruments to measure these forces and the
energy required to operate those tools.
Davidson (18) is among this group, who built the
first integrating drawbar dynamometer with which he measured
the draft of a plow at Ames, Iowa.

He also ran tests to de­

termine the effect of speed and other factors on the draft.
He reported that an increase of speed from 2 to 4 miles per
hour will increase the draft from l 6 to 25 percent.

Collins (19) also ran tests at Iowa State College and
states that:

1) type of bottom does not materially in­

fluence the craft;

2)

an increase in speed will produce

about the same increase in draft with any type of bottom;
3 ) the increase in draft due to speed is confined to that

part of the total which is required for turning and pul­
verizing.

This varies with speed from less than one-third

to about one-half the total draft of a plow within a speed
range of two to four miles per hour;

lj) variation in depth

is probably the greatest source of error in plow tests of a
comparative nature;

5) under some conditions of plowing, a

sharp cutting edge is of little importance; and

6) under

certain conditions high speeds may cause failure to scour.
I. F. Reed and John W. Randolph (6l) have studied the
effect of

speed on the draft and noted that for most

in higher

speed, their relationship is a parabola as

cases

y = a / bx / cx^
They also studied the effect of depth, width, and landside
on the draft of implements.

Data showed the effect of the

depth changes with the kind of soil, and generally increasing
depth will increase the draft.
Keen and Haines (I|.0) state that the relationship be­
tween draft and speed is a straight line.

Tests by the

Bureau of Agricultural Engineering reported in part by
Ashley, Reed and Glaves show that the relation between draft
and speed of plowing may be expressed by the formula

y = a / bx

in which y is draft in pounds per square inch

of furrow-slice cross section, x is the speed in miles per
hour, and a and b are constants depending upon type and
condition of soil.
Keen (32, 3 8 ) states that change in the setting of
the plow or hitch have little effect on the draft, except
in so far as the depth of' plowing is affected.

He also found

that slope of the field affects the draft very little.

Keen

and Haines (3 I4J were experimenting at Rothamsted experimental
station in England.

They studied the resistance of the

soil in a comparatively uniform plot.

The result was that

there were large variations over short distances.

They

represented the differences by means of isodyne contours,
drawn on a map.

They repeated this experiment on the same

plot for several seasons carrying wheat, barley and oats,
respectively, and their conclusion was that the effect of
crop and fertilizer was much less than natural variations
in the soil.

They also stated that there is close relation­

ship between clay content in the plot and the draft of the
plo w.
The effects of crop cover, fertilizer, lime and manure
have been studied by the Ohio, Missouri, Rothamsted stations
and the Bureau of Agricultural Engineering.

These studies

show little or no measurable effect due to ordinary appli­
cation of lime, fertilizer, or manure, but a marked effect
due to cover crop (62).

D. B. Lucas (149), in New Jersey,

used a hydraulic drawbar dynamometer, made in Cornell
University, to measure the effect of the lime in the draft
of tillage tools.

He used a plow as the tillage tool,

and found out that in limed plots draft decreases, but be­
cause of higher yield and good root development the result
might become opposite.
Some rather classical studies have been done in
analyzing the forces exerted on tillage implements, and
also in expressing the shape of plow mathematically on the
basis of the soil dynamic properties.
Theodore Brown (9) studied some fundamentals of plow
design, and found that the surface of the most successful
plow bottom has a hyperboloid equation like

a 4 + "b ■*+ T * = '
E. G. McKibben (51) studied the dynamics of the disk
harrow by analyzing the different forces and moments existing
•in single and multiple gangs.

Sjogren (70) studied the de­

velopment of the offset disk harrow.

E. D. Gordon (31)

studied the reaction of soil on a disk in relation to dif­
ferent factors.
ditions.

His studies were with controlled soil con­

He found that draft will increase 67 percent in

a sandy loam soil with the increase of speed from 2 . 5

to 5

miles, a disk angle setting of l|-5 ° will cause the minimum
draft, and the upward thrust will increase with the increase
of disk angle.

The increase of angle of penetration will

increase the upward thrust and cut down the depth.

With the

increase of concavity,
creased.

the draft and the upward thrust

in­

The larger disk would tend to penetrate better,

due to r edu ce d upward
vertical position,

thrust.

In an inclined form from

draft and p e n etr ati on is in favor of

smaller disks.
Clyde has analyzed the forces acting on tillage tools
and their effect in the amount of draft.
his work

in several papers,

He has presented

in one of whi ch (1 3 ) he indi­

cated the importance of knowledge of the position,
and m a g n i t u d e of the useful

direction

soil force on tillage tools und er

conditions f r o m easy to hard.

He then expressed the u s e f u l ­

ness of this knowledge as an aid to judgment in designing
for stren gt h or applying the pulling force to the best a d v a n ­
tage, and for selecting the best shape of tool for a certain
kind or degree of tillage.
Clyde also explained the two methods,
and the tillage meter method,

the pulling method

of mea suring the soil forces.

Finally he discussed the results of his tests w i t h different
implements.

In his later w ork

finding the u s e f u l force
that this useful force

(lfj.) he discussed the w a y of

in a t-illage tool,

and ment io ned

in a p l ow and disk usually can be com­

bi ned into a resultant force and a couple.
Clyde found that a "speed type" plow bottom requires
less draft in higher speeds
better.

(2 .£ to 1)..5 m.p.h.)

and covers

He gave examples of using soil force measurements

for c o m put in g the load on the bearings of a disk plow and

reported that wide spacing of the bet.rings reduces the
loads because of the overhanging nature of the forces.
Finally he stated that by knowing the soil forces one can
plan for a shop test in a manner similar to its field
loading.

He has also studied plow tractor hitches and

analyzed the forces on mounted and separate plows, the
discussion of which will not be taken up in this section.
Finally, the work of the U.S.D.A. Bureau of Agricul­
tural Engineering Tillage Laboratory at Auburn, Alabama,
should be mentioned together with their complete tillage
laboratory and extensive experimental works (59)•

The

Auburn Laboratory has 11 soil plots, seven of them 20 x
250 feet while four are 20 x 125 feet.
is two feet.

The depth of plots

They are filled with different type soils with

a known mixture.

They have tracks on the walls on each

side and a trolley car can ride on these tracks the whole
length of the plot.

The tools and testing equipment are

all on that car, and nothing can touch the soil except the
experimental tools.

The tool carrier on the frame can

move cross-wise on the car.

The equipment used for prepar­

ing the soil consists of a grader blade, subsoiling unit,
disk, subsurface packer, surface roller and a sprinkling
unit, all of which have been mounted on a car except the
sprinkler unit which mounts on the front of the car.

A

cover car is provided to place over the plow whenever neces­
sary.

Testing equipment consists of two major units:

the

power car with special dynamometer and the plow test unit.
The power car unit furnishes the motive power and measures
and records the components of draft necessary to handle
the job.

The plow test unit measures and records the forces

necessary to hold the rear of the plow in its working posi­
tion.
The three components of draft are recorded on the same
chart with distance and time, thus making it possible to
check the speed and draft at any time.
The plow bottom, in its working position,
tirely by hydraulic units.

is held en­

The plow beam is carried on the

front end by the dynamometer, and the rear end is mounted
on two hydraulic units.

These three hydraulic units, with

the power car dynamometer, will enable one to measure the re­
actions of plow bottom continuously.J,. W. Randolph and I. F. Reed have run different tests
in this laboratory and have obtained good results.

They

used a ll; inch plow to indicate its reaction to different
factors.

Then they tested several ll^-inch plow bottoms

(6 3 , 61;) with different shapes and found that the shape of
the plow bottom affects draft markedly.

They showed the

different effects of major shapes which cause the bottoms to
be classed into different types, and also the effects of
shape variations within a class.

17

The Cooperative Work of Soil Physicists And
Agricultural Engineers
The work of agricultural engineers and soil physicists
covers the study of physical properties of soil and their
effect on the draft requirement of the tillage tools.
In the study of the dynamic properties of soil affecting
tillage, there has been a considerable amount of work done
in some foreign countries and here in the United States.
In the United States, McKibben (50) has made an outline
of the factors that enter into soil characteristics.

After

giving the outline in eight sections, he names three major
problems in the soil dynamic situation.
1)

The determination of the dynamic properties of soil,

their changes, and the standard methods of measuring them;
2)

Determination of what should be done and when, to

get favorable results; and
3)

Determination of best methods and implements to get

those results.
M. L. Nichols has made extensive research on the dy­
namic properties of soil, their effect on the design of til­
lage tools, and the force that is necessary to pull them
in the soil.

His works have been published in six papers,

which will be reviewed here very briefly.
In his first paper (51f) he introduces the classification
of variables that enter the design of implements and com­
pletes his discussion in subsequent papers (5ij-, 56) .

His

lei

classification is:
1)

Primsry soil factors:

particle size, colloidal

content, moisture percentage, state of compaction, organic
matter and chemical composition of colloid.
2)

Design variables:

kind of metal, polish, bearing

area, curvature of surface applying force.
3)

Dynamic properties of soil:

shear value, friction,

"Compression, cohesion, moment of inertia.
If)

Dynamic resultants:

fragmentation, arch action,

compaction, shear.
The assumption was made that the structure of soil is
uniform and cementation is zero.

Each soil has a normal

structure which would afford a basis for quantitative
studies of force reactions.
He expresses that some of the soil properties are inter­
related and also all soil properties are related to the fac­
tors listed as "primary soil factors."

Then, he discusses

the relation between the primary soil factors and dynamic
properties of soils.

Colloid content and the percentage of

moisture content are two important factors in the study of
soil conditions.
He also obtained a quantitative relationship between
soil colloidal and physical properties of soil in non-plastic
soil (soil having less than 16 percent clay).
In his second paper (5^+) he discussed the work on
non-plastic and plastic soils:

the soils for this experiment

were made synthetically by mixing clay with different
amounts of sand.

In the study of non-plastic soils, he

discussed the moisture content of soil for maximum reactions,
and the relation of the force of reaction with the colloid
content.
Moisti^re content of soil for maximum reactions:

as

the variations of the physical reaction of any soil are
due to the moisture films of the colloidal content, it
follows that the moisture percentage at which maximum re­
actions occur would be proportional to the colloidal con­
tent.
the

This would hold only for soils having colloids of
same chemical or absorptive activity.
Nichols ran the tests and then indicated quantitatively

the relationship between M, the moisture percent content
at which maximum activity occurs, and C, the percent of
colloid content.
For

cohesion,

M = .2930 / 6*94

For

adhesion,

M = .183C / 10.10

For compression,
For shear,
also M =

100

/ b

M = .3950 / 2.1

M - .2970 / 4*35
where M and C are as explained before,

7

’

b is the intercept of the equation, and D is a constant
film thickness.
Force of reaction and colloid content:

cohesion and

adhesion, being simple reactions which involve merely the
breaking of films, should vary directly as the number of

20

colloidal films being broken.

Compression and shear, both

oi which involve orientation of particles, should show a
definite relation to colloidal content, but the reactions
would not be expected to show a simple, straight line
relationship.
Fa = .QOkl- C / .1,8, where Fa is the maximum force of
adhesion and C is the percentage of colloid.
Fc = ,0i|9

/ S, where F

is the force of cohesion

in grams per square inch.
The agreement of this formula (the square of clay
percentage) with the colloidal film hypothesis can be
noticed.

To measure the force of cohesion, a given cross-

section of soil must be pulled apart.

A pressure of more

than ten psi was necessary to apply to a soil sample to
get a constant number of films per unit cross-section area.
With the synthetic soils the apparent specific gravity
did change with the square of the colloid as

D - .0012 C

2

/ 5, where D is the gram increase in density pci1 cubic
inch with a given pressure regardless of moisture percentage. •
It will be seen therefore, that when the force formula is
corrected for the amount of colloid, the variation of the
force of cohesion is proportional to the amount of colloid
present.
Fc z -,625c / 12

The amount of Fc , force of com­

pression, varies directly with the colloidal content up to
a point near where plasticity occurs; from this point the

amount of compression varies inversely as the colloidal
content.

F c = -.o25 C / 12 where F

is the resistance
o
force against compression and C is colloidal content.
Forces producing shear are not confined in their
action to 'a single plane.

The interlocking of particles

and the cohesive action of moisture films cause the reac­
tion to spread throughout a considerable mass of soil on
each side of what is usually considered the shear plane.
Under these conditions it can be expected that shear is
the resultant of compression and cohesion.

The maximum

shear value of non-plastic soil is S - .013 C / .5; with
the increase of colloid beyond the plastic limit this
equation will not hold true

©
<■-■ ■■

0

— i ■■ t

4 ---------

10 £0 30
'/.C O L L O ID

Fit.

I

— -------------------------------

40

0

£ 00
('/

4 oo

c o l l o id

.

Goo
)*

O

600

* F IS. a

I — ----------------------- 1----------------------------- 1-----------

0

10
COLLOID

20

FIG. 3

Figures 1 and 2 show the relation of cohesion and
compression with the colloidal content.

Figure 3 shows

the relation of colloid to maximum force of adhesion.

Ad­

hesion is measured by determining the increased friction due
to the "sticking" of a soil to a metal slider.
Nichol also has found an equation indicating the
amount of maximum value of shear is a function of colloidal
percent and the pressure exerted on soil.

22

Pms = - 2 0 /

.7P

where
Fms = shear value in psi
C is the colloidal content (percent)
P is the pressure in psi
This equation is for a soil with large quantity of coarse
sand, but for those composed largely of fine sand or silts,
the indicated shear value is low.
Plastic soils:

The classification of soil as plastic

and non-plastic is arbitrary.

However, by increasing the

colloidal content of soil there will be a point where the
reaction to soil will change and evidence of plasticity
will appear.

Atterberg's constants have close relations with

the properties of the plastic soil.

It was found that within

the range of forces entering into the tillage operations
that
1)

Maximum adhesion occurred at a moisture content

fairly close to the upper plastic limit;
2)

The moisture range over which adhesion took place

and moisture content at which maximum adhesion occurred
were functions of the plasticity number;
3)

The range of maximum compressibility of a soil is

approximately the same as the plasticity range on the
moisture scale;
ij.)

The maximum compressibility of a soil is a loga­

rithmic function of the plasticity number;

23

5)

The maximum resistance offered by a soil to the

passage of chisels is a logarithmic function of the
plasticity number; and.
6)

A double logarithmic relationship exists between

the plasticity number and that moisture content at which
the resistance of a soil to a chisel or implement being
forced through it begins to increase rapidly.
The lower plastic limit is the place of maximum activ­
ity, or the percentage of water at which activity occurs.
With different soils, the physical activity per-.unit of
water will vary depending upon the amount required to satis­
fy the surface demands of the individual colloidal particles
and the amount of colloid present.

The physical activity

of water would be inversely proportional to surface demands
and directly to colloidal content.

It is then expected that

the greater the activity of water the lower the lower plas­
ticity limit.
P = KC / b

or from the Parker and Pate data (5l|) the
ivi
approximate quantities for b and K were evaluated and
P
1

= .3 6 1 - C
10M

where P1 is the lower plasticity limit,

C the percent of colloidal and M is percent of moisture.
y

Figure ij. shows the

40-

V30-

2

relation of the

j ,

place where lower

£

plastic limit occurs W - 4 10
to the activity of

o

the s o i l 1s moisture. J

0

£

1

ACTIVITY
F

\ & .

3

OF

4

4

COLLOID %

Plasticity number:

At lower plasticity, colloidal

film action first became evident, and at the upper elastic
limit the film expands so much that its activity is materi­
ally reduced.

The plasticity number is an arithmetic dif­

ference of the percent moisture content at upper and lower
plastic limit.

This number is a function of colloidal
P^ = .OOij.89 C

content; an approximate equation is

2

'•

Since colloidal content is a mass and the film theory ex­
presses a surface relationship, the equation describes a
mass-surface relation which is exponential.
/

2 .6 7

is close to

The exponent

fc

44

e.

Figure 5 shows the relation
between colloidal content

O .7.

V- •*-

and plasticity number

10 .5.

•&-

o
1.

1
I "" ~l~ ■1--- 1--- r
1.1 1,2 1.3 1.4 1.5 1.6
LOG. C O L L O I D

FIG.

M

1.7

5

.60*1

jo-

c
P H A *E

20- B PHA5E

5

FIG.
D

6

PH A 5 E

20

PERCENT

W ATER

25

In his third paper, Nichols discusses ’’Soil and Metal
Friction" (54)*

Tests were run with synthetic soils and

various known metals.

The conclusions were drawn from

the average of the data obtained from the tests.

According

to the structure and moisture of soil, and the pressure of
metal surface, the frictional resistance was divided into
four phases:
Compression phase (A):

when water does not adhere to

the metal, and when the bearing power of a soil is less
a

than the pressure per unit area.
are:

Factors affecting

speed, pressure, smoothness of the surface of metal

and soil.

To indicate these relationships mathematically,

Nichol ran tests with sand and chose a slider with the
weight just enough to cause slight rolling of' the surface
I
particles.
He found out that
= .OIOS / .33, where
is the coefficient of sliding friction and

S

is the

speed in feet per minute.
Friction phase (B):

(B) phase occurs when the bearing

power of soil is more than the pressure per unit area, and
moisture does not adhere to metal.
this phase are;

Factors affecting in

total pressure between the two surfaces,

and the roughness of the surfaces; contact area and speed
have no effect. An approximate equation for this relationship
i
i
- .OO7 6 C/ 28; where /\
is the coefficient of friction
of chilled iron and

C

a colloid content.

By introducing

the hardness of metal in this relationship it was found:

'Jiri

~ »2l| / .005 C - .0001H, where

JA

H

Is the hardness of

metal determined by the Brinell number, and
as. explained before.

C

and Ji\' are

It was found that 32 percent clay is

almost the limit beyond which the friction will not change
appreciably.
Adhesion phase (C):

In (C) phase, there is enough

moisture present to cause the soil to adhere to metal, but
not enough to appear on the surface of the metal.
fecting factors in this phase are:

The af­

speed, area of contact,

psi, surface and kind of metal, surface tension (i.e. amount
of colloidal material, water percentage, temperature and
viscosity).

An approximate formula for the moisture content

of maximum adhesion for a nickel slider on non-plastic soil,
is

M=

,2 C / 10

and moisture content at which first adhesion appears is

M
M'

= .13 c / If.77

in this case is •

\

.OOZpZp C / .24.8 when
content, and

M

For plastic soil

C

is the colloidal

is the coefficient of kinetic friction.
.7 PL, where

M

is the percentage

of moisture at which adhesion begins, and PL is the lower
'
»
plasticity limit. Also / A - .06 Pn / ,Ij.29 where / A
is
the maximum coefficient of sliding friction and P^ is the
plasticity number.

The effect of kind, of metal on the coefficient of fric­
tion nas not ocen determined very clearly; hardness and
polish have some effect but the angle of wetness is the
i
main factor that changes the M
•
In the study of the friction between metal and soil
in general, the phenomenon of adhesion should be investigated
Adhesion is related to the wetting power of the metal.

A

conception that is generally accepted is that the wetting
power is a function not only of the surface tension of a
liquid, but also of the specific attraction operative be­
tween the solid and liquid.
Parker has developed a method to get soil solution.
P. A. Kummer and M. L. Nichols (if2) used soil solution in
\

indicating the adhesion between soil and metal.

After

studying the principles of adhesion, Kummer (1+3) tested
different plow shapes and materials on scouring in heavy
clays.

He used four kinds of plows:

1) alloy-steel

moldboard covering; 2 ) endless belt type moldboards;
3 ) wooden rollers replacing solid moldboards; ij.) wooden

slats, impregnated with paraffin or linseed oil, replacing
steel slats.

The plowing tests showed that wood slat

bottoms produced considerably better scouring than steel
slat bottoms, especially in the higher moisture ranges.
Lubrication phase (D):

When there is enough moisture

in the soil, it will give a lubrication effect.

The effectin

factors in the coefficient of sliding friction are:

speed,

psi, amount of moisture arid the viscosity, nature of
metal and the surface.

The exact relationship has not

been found in this phase because of puddling of'soil,
but the clay percentage is the main factor in this case.
In the fourth paper (lj.l), Nichols did work on the
soil reactions in the specific case of moldboard plow.
As their work consists mostly with the soil properties
which is common in all others.

A short discussion of

his work will be reported here.
M. L. Nichols and T. H. Kummer (ifl, 55) have expressed
the shape of the curvature of the moldboard plow mathe­
matically, and discussed the relationship of these curvatures
to the dynamic properties of soil.
First they classified the functions of the plow into:
1) the breaking or cutting loose of the furrow slice;
2 ) the pulverizing of the furrow slice;

3 ) the inversion

of the furrow slice; and 4 ) the covering of trash and
weeds.

Eliminating such factors as landside pressure, v/ing,

point, and heelbearings, suction, and other features of sta­
bility and smooth running, this classification centers at­
tention on the moldboard, shin and share action.
As the plow moves forward it compresses the soil for­
ward and upward.

When the shear resistance exceeds the

compression a block of soil is sheared off at an angle of
4 5 ° with the horizontal and slides up the shear plane as

a- solid unit.

The blocks A, B, C, also will form as shown

u✓

in the picture.

With the movement of the plow forward

the soil slips over itself on shear plane "a"; to keep
the soil slipping over itself in plane "b" at the same
rate,- the block B should travel at the same rate as A
plus an additional amount equal to the movement of A.

z

D

X
FIG.

REACTION
OF
CED
THROUGH

7

SOIL

A

3

A

f>LO tA/

ADVAN­

IT

In the same way the plane nc" will move with the amount
equal to the movement of A.

Also, in the same way the

plane 11cf' will move with the amount equal to the movement
of A and B plus the movement of A.
The curvature of a vertical differential section of .a
moldboard which keeps the soil slipping on all shear planes
simultaneously and uniformly must be constantly increasing
at a rate which is proportional to the distance traveled
up the curve.
rate in

Z

A mathematical expression for the increase

direction to

X

direction is

OR
L Z as

OR

t> <«-

finally

hx
z = CLJL-

30

where Z

and

*

The constant a

are coordinates and a and b are constants.
indicates the

section, and the constant
slope of the section.

b

location of the differential
denotes the steepness of the

The upper part of the moldboard in­

verts the soil and throws it into the preceeding furrow.
It is necessary that for uniform scouring the inversion
area also have a uniform pressure.

A mathematical ex­

pression

for the change of angle in this area have been

found to

be

distance

of travel, and

the rate

of turning or throw of the plow.

<f> =.

where
^

and
and K

*

are angle and

are constants governing
Also the paths

of soil particles were found to be sections of logarithmic
or equiangular spirals of the general formula
w u>

R - OL 4L

where

R

is the radius,

radius has turned, and

uu the angle through which the
a

and

m

constants.

Nichols and Doner (26), after finding the equation of
plow surface which indicates uniform pressures for pulver­
ization and inversion, discovered another force which they
called "buckling effect."

Through mathematical studies of

forces acting along the path of travel of soil particles,
they showed that this effect at certain points increases
the forces normal to the moldboard, thus materially affecting
scouring.

By developing a mathematical equation they found

the tangential force necessary to maintain motion in terms
of friction, length,

curvature of the moldboard, and

weight

of the soil at any point along the path of travel.

They

showed that high curvature in the path near the shear re­
sults in increased tendency for the soil to stick to the
moldboards.

If the curvature is shifted towards the wings

of the moldboard, this tendency is materially reduced.
M . L. Nichols and I. 1. Heed in their field study (58),
discussed the physical reactions of soils bo moldboard sur­
faces,

They classified the soil according to their physical

conditions as:

hard- cemented soils, heavy sod, packed or

cemented surface, freshly plowed soil, push soils, and fi­
nally normal condition.

The reaction of soil in good plowing

condition is described from field studies.

They found that

the pulverization of the slice is produced by two sets of
shear planes .

The primary planes were formed by the wedge

action of the point of the plow and extended upward and for­
ward from the shin at an angle of 1(5 degrees to the direction
of travel.

The secondary planes were formed at right angles

to the primary planes, and sheared the soil in two directions
which produced pulverization.
Nichols states that the so-called "tension" effect of
the plow is found to be due to variations in directional ac­
celeration .

OBJECTIVES

The objectives of this study were
1)

To run some field tests for the indication of

the draft requirement of different tilling methods.
2)

To run laboratory tests in a soil box to find

the relationship between the draft requirements of tilling
implements and the different effective factors.
3)

To introduce a theoretical method to check the

result of the laboratory work and to find a single equation
to show the relationship between the force of soil re­
sistance against the tillage tools, and the effective factors.

GENl k AL INVESTIGATION OF THE PROBLEM
Factors That Affect The Draft
As has been mentioned previously, the problem of
tillage is one of the oldest and most complicated ones
in the field of agriculture.

Different investigators

have tried to approach this problem from different points
of view, but because of the complexity of the nature of
the problem no definite solution has been found.
In the study of the draft requirement the first step
is to investigate the variables that enter into the problem;
then, find out which of those variables have any effect and
in the event they do have an effect, determine the relation­
ships between them.
The variables that exist in the tillage operation can
be divided into three sections:
Soil variables (primary soil factors)
1.

Particle size and percent of colloidal

2.

Chemical composition and the effect of organic

matter and fertilizer
3.

Moisture percentage

[j..

State of compaction or apparent specific density,

a means of indicating the structure
5.

Effect of vegetation and crops residue

6.

Effect of slope and non-uniformity of soil

Implement variables
1.

Kind of implement

2.

Kind of metal

3.

Surface condition and the sharpness of the

implement
ij..

Bearing area

$•

Curvature and the shape of surface applying force

Factors outside of soil and implement
1.

Speed

2.

Width and depth of the furrow

Some of these factors cannot be evaluated at present
3 and though their effects have been proved by several inves­

tigators, the determination of any mathematical relation­
ships have not yet been found, e. g. the effect of vegetation or
fertilizer.

There are also some other factors affecting the draft

which have proved to be negligible, such as the slope of the field.
Therefore, in indicating any draft functions only the vari­
ables that have significant effect will enter into the dis­
cussion .
In the design of tillage tools, attempts have been made
to specialize the implements to work in particular conditions.
This not only will Improve the quality of tilth, but also
decrease the draft and eliminate some of the above-mentioned
design variables, for example, making cast iron plov/s for
sandy soil; or selection of the optimum curve of moldboard
plow for sod, sandy and clay soils.

Major Factors Affecting the Draft
Nichols (55) in the study of plow shapes has analyzed
these functions as cutting loose and pulverizing the furrow
slice bj the action of compression and shear; then inversion
and covering, by pushing up the soil over the moldboard
curve which inverts, and throws the soil into the furrow.
On the basis of this analysis the variables that affect the
draft are;

resistance to compaction, shear friction, com­

pression and adhesion, and also speed which indicates the
rate of those actions.
Nichols, in the study of dynamic properties of soil
which have been discussed previously, has indicated that
the above mentioned properties are functions of the following
factors;

composition and the percentage of colloidal con­

tent, moisture percentage, apparent specific gravity, and
the speed of implement.
The indication of a single equation covering the effect
of all these variables experimentally is at present next to
impossible, though the relationship between the soil prop­
erties and the above mentioned factors has been indicated
experimentally.
Thus in the present experiments, only the following
factors have been considered for study:
1)

the percent of clay;

2)

the percent of moisture;

3)

the apparent density; and

L\.)

the speed of implement.

In the laboratory experiments the other factors could be
controlled or kept constant.

In the field test, attempt

was made to select plots with the apparent uniform condi­
tions,

though there were some differences which could

not be measured because of lack of means and methods of
measurement,
The biggest problem in the field test is the non­
uniformity of soil and the non-controllability of the fac­
tors.

The U.S.D.A. tillage laboratory at Auburn, Alabama

is able to run tests with controlled conditions.

They have

obtained very useful data on draft under different conditions.
The Auburn type of experiment station, though very useful,
has the following handicaps:

1 ) high initial investment

which makes it very difficult in other states to duplicate
the investigation; 2 ) only 11 kinds of soil which are common
in the south have been tested in the plots.

To change the

soil of each bin to different types requires a tremendous
amount of labor and time.

There are some other difficulties,

e.g. the need of a long time to obtain a uniform moisture,
controlling the bacteriological action, the accumulation of
salts in the plot soils by drying and wetting process when
the non-distilled water is used, etc.
To overcome the above-mentioned difficulties, the author
decided to investigate the possibility of finding a new and
better method of experimenting and also to find out the
relationship between the draft and the affecting factors.

METHODS OF PROCEDDRE
Three methods have been employed to complete the
investigation of the subject:

field work, laboratoryr

work, and finally-, mathematical solution with the help
of dimensional analysis.
Field Work
Field Tests
The field work consisted of indicating the draft
required to pull different implements in three plots of
soil.

The types of soil selected for the experiment were

clay, sand, and sandy loam.

The clay soil was Conover

clay loam, without any crop and with very little vegeta­
tion.

The Hillsdale sandy soil was covered with clover

and oats; the Hillsdale
years.

u.idy loam was under sod for several

The experimental plots were located to the south

of the campus.

Although attempts have been made to find a

comparatively uniform soil, the transportation, weather,
and time were problems which prevented the selection of
plots away from Lansing.

For preliminary tests, the plots

were arranged in the form of a square with 3 ^ sections.
The size of each section was 60 by 20 feet with a 15-foot
alley on each side to provide space to maneuver the tractor
and implement for return trip.

Each of five methods of

tilling were practiced in six randomly selected sections.
Six of the sections were not used.

The results of this test

were not satisfactory because of the short period between
start and stop, and the packing of the soil by tractor and
implement wheels caused by inadequate space for moving them
within sections.

To eliminate these difficulties the second

time, long strips of 300 by 10 feet were selected and divided
in five sections of 60 by 10 feet.

Each of these strips was

tilled in one run with a different implement and then the
average of the draft required for each section was computed
separately.
The methods of tilling were
1)

Conventional plowing (plowing, disking, harrowing)

2)

Plow with plow packer

3)

Plow with cultimulcher

4)

TNT plow (sub-base plow)

5)

Disk tiller

The selected Implements v/ere the ones that were used in
previous tillage experiments conducted jointly by the agri­
cultural engineering and soil science departments to deter­
mine the effect of tillage method in the yield of crops.

The

implements consisted of:
plow:

a two-bottom, 1 4 -inch plow made by International

Harvester, the trade name is "Little Genius No. 8 ";
disk harrow:
harrow:

John Deere tandem disk, seven feet wide;

spring tooth harrow;

packer:

a plow packer, made by International

Harvester with six wheels.

The diameter of the wheels was

twenty inches;
cultimulcher:

made by -Dunham.

It consisted of

two rows of notched disks at the ends and two rows of
spring tooth harrows in the middle.

Its size was 3 by 6

f eet>

TNT plow:

made by Oliver.

Has two nine-inch plow

bottoms and two smaller bottoms connected to the same beams
with three inches more depth which gave a total of 2 by llj
inch furrows;
disk tiller:

a

m 256-A"

John Deere tiller with five

disks and spacing of 10-2/3 inches between disks.

The dia­

meter of the disks was 22 inches and concavity was two and
one-half inches.

All the implements were the trailing type.

The draft was measured by a hydraulic dynamometer made by
Messrs. H. Fish and Garth Hall in the department of Agri­
cultural Engineering at Michigan State College.

Some minor

changes were suggested by the author in order to improve
performance.
The following data were taken for each section of the
plots:
1)

The draft requirement of different implements in

indicated sections;
2)

The mechanical analysis of the soil (average of

three samples in each section);

(7 )

Fig. 8 .

Dynamometer for field tests

4i

Fig. 9.

Field test with two-bottom, 1 4 -inch
plow.

42

T h e E s t e r l i n e - A n g u s C o ., I n c . ,

Pig. 10.

indi

A sample of dynamometer graph

!o

■ P !t!

Cm

"i—I

•

0

•

O 4 CO

0 0 •

fi« p.
co

0

ft
-P

+s;;; •
• co
0 &&
P © i—!
ft w

ft

CO O
C O -A O O
•
• •
p -_ to
H H H

UYLOCA
O C\J OJ
• • •
A P -C A

cp
•

c P rH c O
lA U ^ c O
P -c p c O
PJ C\i r—1

rH
• • •
OJ 0 0
C O -z j-ft
i-4 r p v O
1
—1 1
—1 rH

■CO
•
• •
-Z tftC O
C A 'X 'L A
fp lA -t
rH 1
—1 1
—1

i-0
CO O - - X •
• •
OJ rH CP

z z K A -z }1 I rH 1
—1
• • •
C P f t OP

u \c o o j
• • •
t A 'U 'Y 'O

vO PJ

rH CP
0PvO 0 •
0 •
c o C A cO

rH CO
O z J -C A O
•
• •

CO ( A O
rH

PJ

lA
•
• •
P -lA C P
P -G O 'X >
O i—1 CA
l A PJ rH

c p p -lA
C A lA -z j•
• •
rH rH OJ

IP C A P J
p -ip c p
• • •
P I rH C p

-z tP -C O
CO PJ O
•
• •
rH rH PJ

vO vO X )

CO
• • •
vQ ip H O

00 P•
• •
P -P -P -

03
•
* •
0 3 -z p O

X5cO H
P J .X - U N
• • •
H H rH

o try X )
ft-z t-z j• • •
rH 1
—1 rH

-J -c p c p
C\l - z f - z t
•
• •
H H H

(\J C O P
PJ c p _ j •
• •
rH rH rH

P lC O O
PJ c p _ J • •
•
rH rH rH

b -lA O
PJ P - c o
• • •
C O lA -z jH

u \c o O
U M A r-i
•
• •
vO U \ 0 1—1

O CP OJ
-z N O c p
•
• •

-z tO O
rH CO - A
•
• •
C A -Z t-P J
rH

vO LpP-j-O A
•
• •

•

•

rH
e •
rP O
C A rH
fp o o
H rH

CP
rH P - P J
• • •
1
—1 rH CO
PJ rH

•
O
ip

0

•H

d

O

0

0

P

X

XI

-P

O

ft
M
•ft
>H

43
<D
£
bO

(X P
<
*H
5X r—I

H

S
M
ft
£3 ft
PQ K
Ph
g
ft
o
Eh
£
CO

ft
pH
ft
0

Eh

,— (

*H
43
XI
o

ft P
0 •iH
ft

43 ft
P 43
0 *H
01

P

0 a
p, 0

ftQ
<

0
-P

P

P 2
0 43
o

01
P -H
0 O

0

ft S

P

CO

0

O
<m
w
0
o
*H
-p
o
a)
co

sO
ft

O
<i>
60
0
p
0

>

0 >-

C O lA i-P
rH

H0 VJ

PJ O O
rH r—i ,H

rH v O
•
•
---------1 rH
— —f OJ
" O l'- H
• a •
0 >0 p Al
OJ

H 0*
• •
0 r - o
PJ -1 0J

P O 'O

0

U \ A O
• » m .
f t P -c D
PI ft Pi

C P 'O
r
rH rH c p

- A - A ■A
•
• •
A p J '
—1 S PJ

P
0

VA H

V \P ) P i

0

v O pJ i A
nO p h a

O

P - c j -4
P P A

fp O
•
• «
-\J O '
O N J -

H O A
•
■ «
C A ^"k-O
v£> P - X -

rp P -O
•
• •
p ( \lO
J 3 P
#

d
n
O 0
CO CO

■d {>»
d
p 0
O 0 rH
CO CO O

« t
p
<

o
•rl

Q
*
X <vN.
o
n

O

• m m

p
-# »*c«•

60
P
•H

d
ft
d
0 0
O 0 ft
CO CO O

•r-f

1—1

Eh

0
p

ft

O lA lA
rH

ft

m

•

tj

•

ft
m
rH

0

3 A
T
•
• *
■J ' A O
rH
-\J

z j- c p .1
•
• •
rH ( A O
rH
r-J

CP

d

i>>

d P 0
O 0 rH
CO CO O

:f A

* •

•
H
H O
H rH J

—

d
p 0
O 0 H
CO CO O

d

0

0
ft

X!

ft

o

■ft

o
X

43

0

P
0

X

0

•H

O

0

43
p
0
>

P
O
O

5

ft

0
H
ft

X

U

X

•H

O
H

&

P

£
O

ft
ft

£
O
rH

ft

P

0

43

&

Requirement

Q

ft X

43

0
—1
1
—1
•H

*
•
•
EH

x

01
•H

ft

ft

Draft

co
ft p
O
Q ‘r-t
w
Eh •»
d

x!

0
•
0
Ph
ft
CO
£

CO

' i‘ 1
L
r4

•
P • CQ
d o’p
G <D H
P«
•
•
o
0
P•
a
cn s
«
-p g
p
0
p

A

-P Ai
G -P
0 *H

SH to
3G
P©
PQ

HO caIA

OlfMAlA

CO CO A— A— C—

a- co
ho a -

-d*cA

A -A -A - H O -M O

HO CACM CAIA
lA'ACAco O
o-iso-(\jir\

a-ho i a

co

rH C A A -C M CO

U\cAO
1A• O•
•
•
*

I A--CM C\J

HO i— IHO HO cO

HO lA L A I A

lA A -d -d -c r

•

•

•

•

•

•

•

•

•

•

I A A - t— l A v O

ia

HO O CACO I A
CM CO C A H C\J
O O O r H CA
rH
rH

i—I X A i—11—I O ' i—11—I CO C A C\J
rH CO C M C A d * l A A J r H - C r C A
H H C M C M O
r H O O O O
i—I rH rH i—1 1
—I rH i—I i—I rH i—I

M O HO sO A -1 A
rH rH rH rH rH

CA OJ C\J CAAJ
rH rH rH i—I t—I

HO 0 - 0 A-rH
A-U\A'-'tf\H0

rH rH rH A~-"LT\
O O C T 'O O s

O J - d - l A C M rH

A"H0 HO HO vO

C O O C O O O O J MO A—O C rH
- d - C A C A r A - c r A H A A - I A HO

CM

i— I rH i— I rH i— I

i— Ii— I rHi— Ii— I H H H

•

•

•

•

•

rH rH r-H i—I rH

CACAO

H H

<A
CA
c A r H GO rH cA

aHO i—I l A r H H O

HO CA A CA
HO cO CO CAIA

CO CArH

A - A - A - CO A -

H O H O H O A -H O

A -IA IA C O H O

lA -d -U V O I P

A A A C O

CA
CA
C A H CO <H c n
A

-d-UMA-d-lA

-d-lAlA_d--d*

I A i— IrH CA CA

H CA A - - A d ATA-d-A-d-

CAHO A O CO
d d l A A d

H O H A
-dAA-d"A

rH rH rH rH i— I

iHrHr Hr Hr H

HrHtHrHrH

H H H H H

H H H

C A A C O CA A
CM C A H O -d 'H O

CO A O

COco A-HOCO

COCACAA-A-

rH O

H IA

H H

<1

0

■P U
a p
0 -p
om
d *H

©o
PS

f \ J H H

t—

CAHO

A AA
A- CAA- caacO CAA
H A A CAA COA<5dA CMAVO-cKO
A O CACO H COOOCAO OOGO A-HO CO
rH rH

rH

01
03 V

OP FIELD

rH

—1

CO O
G

A-

• •CM•HO
••

CO O

•A-• • •CO
•

AAt •C•
••

» • ft • «
o-d H CO CA
HHH

1
—I rH H

-H H CMCO CA

H (M CM CO O
i—I i—I f —I
rH

O H C O O CA O - d H CO CA
rH rH
i—I i—I ■—I i—I

•-O MO CM C A 0

O A O CAO

O vO CAO O
•
• • t v
rH O A-:hA
OJ ■jrH ‘
—5rH

0 OCA -O o• MA
%
ft • - • •
A i-HA— O !
rH O
•'M (M rH AJrH CVj

•

•

• • *

<3?

THE

•

C\jCM

O :
rHI

•

•

H ;—{

•

•

A -O
rH

l i t
M CAA-

J 1i
—1rH

gA o

HA
d'cA.d'
•d-dcA
t
• • • Oft _d
•
•
• c
ftnft ■ • » #
I A H iA
"O A ---H A— -H* CO A - o o.a
r - A*A JOHO C*- A - H 0 0 A - 0 A - V i)

-d
d-A-4
«*-•
• *• d•
d * CM A A no d a - a - a -

H A
A -J O

H

rH C\J C A _ d - lA

A

CM A - d * A

•

•

H

CM c A - d - l A

C A -d lA

rH

as
G

O

bO
g

X1 -H

O H
Xi H
- P -H
0 Eh

m

o

*H

G

0

r*

G

O
O

-P

^
o
rH
P

•H
&
&
O
rH
P

G
©
rH
rH

©

£
o
rH

P
S

•
Eh
•
•
Eh

TO

•H
P

•H
&H

HC

0
rH
P

iti\-

Requirement

o5 _

A Q
o 2 X*
£
s <

•

Draft

G

•

O rH

Packer

RESULT

V*
o J_ X

1

rH ,

2

TESTS

(LONG

STRIPS)

IN

SANDY

SOIL

•
-p# •H
<H • •
c
o' TO
•
St
-f
,©
pp P

$

e5

OJ A O J rH A

*

p

•rH

co cr

03

P 0
QW

a

Q«
rd
a

P
p
p,
(I)

O

O O

'-O'UY'O l A L P

A C O c O COCO

A A A vQ A

Ia ^ I A I A I A

H A co A c o
O-OJ O - d H
COA AcO A
H H H H H

c\l A A oj o
a A d A o
OJ OJ A H OJ
H H H H H

O -d A A A
A A O O O0-0-0- O-A
rH r—
I r—
1H H

A ACM AOJ
O-CO H d f A
A A A A d

OJ A d

sOOO O o

CO C A C M A N

CO d - d A
O-HdcO A

dO I H dco
QOCOO COcO

A

CArOrA-d-CA

C
M(AH OJ H

OJ C
MAOJ C
M

C
MC
MC
MA C
M

CO O-

AO• • • • •
V
'£) V
-QCOC^C^-

'-OTA

A CO

OJ O O H CO

COO -O Jd A
A d d d a

CO CT'CO

Pr
s

•

P

H

•

•

•

ACO

A OJ

CO

A

rH l A O '

A

sQ
Ol A G O

A

•

A d

•

«

•

CO
•

*

r
—11—11—Ii
—11—I
C
MC
MO- 0—
O

gOCAO

AA A
■

•

A

OJ

H A C-ACO

CAO A o O
rH
rH i
—I
CO

H O

C
M0
0 AdOJ

OJ CA<A(A CA

CAH CO COA
•

•

•

•

•

•

•

•

0 - 0 -CO O-CO

d3 M3M) '-■QA>

IA C
—A vQ\0

O CAO COCA
d 'A A d d

d d A OC
M
d d d A A

d A

9
P >s
£ P
C
D*H
P m
«S C
P 0
P.Q

• • • • I
H H H H H

•

•

•

•

•

H H H H H

H C
MA

i—
I I—
Ir—
I H t—
I

t—
I H r—
I i—
I (—
I

OJ
C
MOJ
0-O-H O d

A

d d A A O l

• • • • »
-dAdO l C
A

■
—
I H i—
I r—
I i—
I

1
—
I H H r—
I

I
—II
—II
—II
—II
—I

p 0
P U
0 P
OP

J
h W

A

OJ C
MA H A
* • • • •
A d A d H
H H H H H

A n rO - cm H
H H i—
I H i—
I

A
AA
-ta c o o-h
•

•

•

•

•

ACA
OJ A O

C
M

a

•

•

ao•

AdC M dA
OJ H OJ OJ H

•

rH

aJ
O

H

p
«5

rP

o
<
D

§

P •

.)

>A a

*

*

«

•

•

co

A

•

•

•

CO CM-d—
dO

H OJ C
MOJ OJ

J D

-OcO

•

•

•

•

•

•

•

•

•

•

A•

f—H d A O
H OJ OJ OJ H

0 -0 C
MOJ C
—
H OJ C
MOl H

,:d-0 O d - O

A A

•

*

e

•

•

*

•

A O A H O
H OJ Ol C
MC
M

o CAO J

O ° A
•

•

• • » •
\CM A CJS

•

A

H A A CAA
d ^ d (,i<v'

O ACA A A
C
MA A A A

O A ; 0 A-CA
A A o 'i AOJ

0—
C
M
' .J A co
eg A d
O)

d d .d d C ,s

d dA d-d

o

d d d d O ’

CA 0— OJ -A CA

A o j AO--XJ
'A d A d - d

0.1 U\ A- H C
M
A d A d A

u \ o-,h
A d A H A

o~ o d

Jo

A A A

dA

H OJ A d A

H OJ A d A

H OJ A d A

H OJ A d A

OJ OJ A

A

d

H OJ A d A

d-

• *• • •

e
g d -j’Acg

•

r *r d•

d

•

•

13 5

« s.

aJ

<H

o tiO
p
d •H
o rH
P rH
p •H
a) Eh
S

C
O
•H
P

d
0

>
c

O

o

o
Or

H

rP
PH

&

%

o
P.

H

U

0

P

A

0

o
r
—
l
P

S

•
Eh

•

•
Eh

di
m
•H

Q

H
H
H
EH

p

Sh
C
D
M

&

O

H

P
-.

o
C
ti

FM

Requirement

•

Draft

•

A

RESULT

C
MACM
H O CO

ao

0 H
Pn o
S

OF FIELD

TESTS

(LONG

<

THE

TABLE

III

STRIP)

IN CLAY

SOIL

(D
C/3

A AOJ ACM
O-dCO O r H

•

CD

CD

C\]
OCO
CO COCO A O-

IAIA

•Pv
<H •
Oj O*
U

NHCO OcO

ft •
co cr
Ph

•
p

Q K

SOD

SOIL

xi ,£
©
© ft
ft
(/J
S

f>s

£ p
CD f t

5H W
CO £
f t CD
ftO
<«!
(D

£ 5h

c

COCO

t—

•

o-o
•
•

•

O — CO

ft r— I
•

m• oi

co c— co co r—

1— I r H r H r H r H

C A ’- A
p }T — <A
rH O

co

C O P

rH

co ~ r O O c a
OJ O J s O

•

•

•

ft AJ
•

•

C O C A O -C A C O

CM CM ft Ol CM

* • • • *
'LCWMAinlp
CO pj-CnCApt
c-—m d c a c o

oj cm
sO vO
O O
•

c\j oj c\j

J A l A s O O CO
O t A 0 - COCO
p j - p ± O J c a p |-

i
—Ii
—Ii
—Ii
—Ii
—1
0-00 CA

OOJvOlA'J3
00
• • • •
C— C\J
OJ r A p j-

C\J C\J C\J C\J 0 0

IA'CACACACA
• • • • •

OJ 00 OJ

•

•

•

•

oo

O

O a O
O O

O AC O P
C O C O '- O

OJ oj

ft P P

O f t f t CO P j COCO O v O 0 0
C A C O 0 0 CO C A

P i —I ft

v O c—
CACO

CA'O
■T f t C O

C A 0J C A C A OJ

vO\OvO-0 \ 0

ft O oo oo C A

C A C O L A O CO
C A P P AJ P

v O OJ C O I A C A
O P 00 00 O

ft ft rH ft ft

i—

P CO
CAO—
O O © © CA

O' o pj-co CA

-crCA O'-0-A)
vO O pfpf-<A

co A)caca
CO-lacAp J-oj

oj

n p

CO
CO
CO
00 -C T O C O C O

O

-CtC)UYLfY'O
P
C O v O O OO
CAPhPrCACA

o-o— o-r— o— vO^OADvo

i
—I

o-

1— i r H r I i—I i—I

C A C A O

•

vOMO-OMDvO

O•CA^
d~
• • 0—• •

PTfAfAcACA

OJ 00 C A C O

CACACAC AC A

0 0 rH C A C A O ]
•
• • • •

0 - H 0 ^ 0 OJ
f t i “ O J O J CO r H

•

•

o-vo
■

•

•

•

p

N

•

•

o

•

•

If t

f t

P

P

CO

CO A J CO p t p r
P 00 C A P C A
P

f t

f t

P

f t

i— I f t i— I i— If t

00 O - c r O - O O

o coco cop
ft
p

O 0- 0-p)c0

COOJADCA'-O

O MD U\'U~\CO

00 00 OJ 00 0J

00 OJ 00 OJ 03

0J 0J 00 A ) OJ

OJ OJ OO OJ OJ

00 OJ OJ CM OJ

A 3 C A O J C J A 0ft ft ft ft

i— I O'' °0 P p J -

-H

ft o

3

W
•H
W

-rN
i
—I ci
cd
£

•

O CACApj-OJ
ft ft ft ft ft

•

•

•

•

m o f t oo o

RESULT

<1

ft
co ) ca c— r—
cd
— ! 0J CJ CO — I
o
•H
£
coi "> CO co
cd a
,£
a 2 v- H 'O
O
©
o-uvo c a o n
G •
£

ft OJ r A p J - C A

•

•

«

CA O O

c A p h P O roj oj oo o p
CO

CO CO A 3 rn

• •

•

•

•

r
—o co

P OJ ft 00 ft

OJ CM -Oj C ACA
OJ CM C\J ft P

co aj N...JM)
ft OJ CJ P OJ

co -j © oo ao

co co co c o o

co -O co 'O co

rnco

• • • • •

• • • • •

• • • • •

O C.! O -.j-ph
-O 0 - 0 -o •
.
—

-H O CO CM

o
C- t— O -O 0-

C
O
)COc
oo o
P>P3P)P> t"- rn -OO r-O

ft OJ C A p J - C A

ft oj f O p j - C A

ft OJ c A p T M A

CM A - - Q c o m

ft OJ C A p T C A

O

ft
O

bO

£

X> f t
O ft
r £ rH

Aft
© EH

o

G

fs
O
i
—I

•

o O O CO o
* • ••*

ft 53
rH
a
o
•H
P
G
©
>
a
o

•

C A CA

P
♦rH
&

a-.

o

ft
fc ,

Sh
©
o

U

XJ
rH
3

S

©

ft
P
ft

•
EH
•

Eh

53•

ft

EH

P

n

-G

p
•H

s
&
o
1—1
Oh

u

©
o
©

Ph

Requirement

OF FIELD

TESTS

a p
£ ra

THE

TABLE

CD P

©

OJ

•

Draft

(LONG

IV

STRIPS)

IN

X!
p
ft £
CD
•H
Q

f t

•

,

ft •
cd o ra
U a A

A

<AMDM j O C A

0 - a -c o ^oco

fn ©
«

0 - 0 -

• • • • •

IQ

oo A —

< A O J r H r H CO

-£~co Caco p ±

'+7

3)

The moisture percentage of the soil immediately

after tilling;
ij.)

The apparent density of the soil before tilling

(three core samples from each section);
5)

Depth of the furrow (depth readings were taken

every ten feet in the furrow);
6)

Indication of speed for each run.

The draft at each instant was recorded on the dynamometer
chart.

By indicating the area of the draft curve with plani-

meter, and multiplying by the spring factor, then dividing
by the distance traveled, the average draft requirement for
each run was calculated.

The speed of the tractor was calcu­

lated by dividing

the distance traveled by the time.

distance and time

was measured from the chart. Figure 10

shows a sample of

the dynamometer chart.

cates one second time

This

Each notch indi­

and the length of notches

is proportional

to the distance traveled by the implement (one inch on the
chart corresponds to twenty feet on the field).
Results and Conclusions
Data taken from the field tests were recorded and the
results can be seen in Tables 1 through l±.

In general, the

result of the field test was not accurate and satisfactory
though some general conclusions can be obtained.

The conven­

tional plow method required more pulling force per inch of
furrow section; the disk tiller has the least pulling force
in sandy soil; in sod, the draft requirement of the disk

tiller was the highest among all.

The effect of the pull

of the packer 01 the draft of the plow was negligible;
the plow packer combination is the lowest energy consuming
method in all three kinds of soils.
As the soil factors in the field condition could not
be controlled, a more specific conclusion could not be
obtained.

Although the soil in each plot appeared to be

uniform, the mechanical analysis in each.section differed
from the others considerably.

The moisture content also

varied in different sections of the plot.

Speed varied

in some sections although an attempt was made to keep the
tractor speed constant.

The effect of root, vegetation and

organic matter, especially in sod and sandy soil, were of
importance; but no satisfactory method exists to evaluate
that factor.

The Indirect effect of organic matter will

appear in the moisture content, soil aggregate analysis, and
the apparent density of the soil.
In conclusion one can say that the field test is good
only for an approximate indication of the draft requirement
of different tillage methods under a normal tillage condi­
tion.

For any specific results the laboratory and theoretic

methods should be employed.

4;

Laboratory Method
The field tests not only do not give satisfactory re­
sults, they also require a special season of the year, with
good weather and workable soil condition.
consuming, expensive and difficult.
above mentioned difficulties,

It is also time-

To overcome some of tlie

the author decided to work on

the possibility of some laboratory tests.
In reviewing literature, the author noted an article (25)
by A. Vi/. Clyde in which was suggested the possibility of using
a soil box and small tools to determine the effect of soil
factors in the draft requirement of tillage tools.

Although

the article was published in 1 9 3 9 * the idea never materialized.
To continue the study of tillage problem the author de­
cided to design a soil box with reasonable dimensions, which
could be constructed in an agricultural engineering laboratory
and to run the tests.
Objective of the Experiment
The objective of the tests in the soil box was to deter­
mine the effect of any individual factor in the draft require­
ment by keeping the'other factors constant and changing this
specific factor.

Effects of speed, moisture, percent clay,

packing the soil, were investigated.

In this test all other

factors, such as organic matter of the soil, cementation,
vegetation, etc., were eliminated or controlled with reasonable
accuracy.

Soil Box
The experimental soil box consisted of three sections:
the st ati ona ry part that held

the soil,

the moving section

w h i c h carried tillage tools and a spring dynamometer to
measure the pulling force,

and the power section which con ­

sisted of a three-quarter horsepower electric motor and the
transmission.
St ationary section:
of the box.

The box was

This section consists of the body
twenty feet long,

and one foot deep. The whole
w i t h two removable

three feet wide,

box was made from a steel frame

end gates. The

covered w i th 20-gauge sheet steel.

interior of the box was
The steel sheets were

at tached to the steel frame w i t h a few wire ties.
upper edges of the box,

Along the

two rows of door-hanger tracks were

bolted in each side to the m a in frame as is shown in Figures
1|3 and irfj., Appendix.

The box was thirty inches above the

ground,

and was supported by an adequate number of cement

blocks.

The entire frame was made with angle steel beams

and, because of ample support; at the bottoms and because
of low-bending moments,

the m a i n beam of the frame was com­

paratively light.

The detail of the design has be en shown

in Figures 1+1, l±2,

i+3,

and

1+6, Appendix.

A check, of

the strength was made wherever it was felt necessary.

The

removable end gates were to facilitate the loading and u n ­
loading of soil f r o m the box.

The box could be loaded by

a tractor w i t h a hydraulic lif ting bucket or simply by

throwing the soil in the box with shovel.
of the box was almost fifty cubic feet.

The capacity
Because of the

comparatively low capacity of the box unloading or loading
of soil did not take more than one and one-half to two
hours .
The moving section:

The frame of the moving section was

made from two diagonal and two longitudinal

2

x

2

x 1 /8

inch

angle steel beams, bolted together in a rectangular shape.
This frame was attached rigidly to four trolley door hangers,
which rolled in the previously mentioned tracks.

This pro­

vided a low friction motion of the frame along the length
of the box.

A third diagonal 2 x 2 x 1/1+ inch angle steel

beam was bolted almost in the middle of the frame to hold
the tillage tools .

A 3/8 inch wide slot was cut along the

length of this beam to provide a location change of the
tool anywhere along the width of the box.
was welded vertically another 2 x 2 x 1 / 8
carry the dynamometer.

To the same beam
inch beam to

This dynamometer was a spring scale

which was graduated to one-pound divisions.

A one-inch inside

diameter and. 1+.5 inches long dashpot was made to dampen the
vibration of the spring.

The dashpot was bolted to the ver­

tical beam underneath the scale.

A one-half inch short

horizontal rod was fixed with two nuts to the weighing loop
hole at the lower section of the scale, and the force of
forward movement was transferred to the scale by this rod.
At each end of this rod there was one quarter-inch hole.

Tne necessary power to move this whole frame was supolied
by two one-eighth inch flexible aviation cables.

A quarter-

inch bolt was brazed to the end of each cable, and the bolts
were held with two nuts in the quarter-inch holes of the
horizontal bar in the dynamometer scale.

The cables were

directed to the drum at the power end of the box with four
rollers which bent the cables in reasonable angles to make
them horizontal and parallel to each other.
The tools were attached to the frame by individual
beams made especially to lit their shape.

Several holes

were drilled in the tool beams to obtain different furrow
depths.

Special arrangements were made on the moving frame

to hitch the roller-packer behind, and to attach the scraper
to the front diagonal steel beams.
The power section:

A three-quarter horsepower capacity

electric motor with 1 7 5 0 r.p.m. furnished the required power.
A variable speed reducer with V-belt was available to the
r.p.m. of the motor from 1:2 to 1:5.

Another set of pulleys

with the reduction ratio of 1 : 5 was used to transfer the
power to the drum.

The drum was made of four-inch steel

tubing welded with two steel plates to a three-quarter inch
shaft in the center of the tube.

Two self-aligning journal

bearings at both ends of the drum shaft provided a free ro­
tation of the drum.
pieces of 2 x 2 x 1 / 8

These bearings were located on two
inch angle steel beams which were

bolted to the end of the box.

A loop was made at the end

of each power cable, and two three-eighths inch bolts were
screwed through these loops in the drum to hold the end of
the cables tightly in place while the drum was turning.
Turning the drum caused the steel rope to wind around, it,
and, in this way, to pull the moving section forward.
Special arrangements were made to get a uniform winding on
the drum to obtain an equal pulling effect in both cables.
The length of the cables could be adjusted by screwing or
unscrewing the 1/1+ inch bolts at the end of the cables.

A

double-pole, double-throw switch was .used to run the motor
forward and reverse directions.

This forward movement of

the tool cart was accomplished by the pulling force of the
electric motor, but the reverse movement was by hand or by
gravity force of a hanging weight at the other end.

A

second switch was installed at the opposite end to turn off
the motor line when the tool cart reached that end.
To indicate the friction produced by moving the tool
cart along the box with different speeds and loads, new
additions were designed and built:

a piece of one-eighth

inch flexible aviation cable was connected to the rear end
of the tool cart, and after giving a 9 ° degree bent around
a six-inch pulley, it was drawn up 25 feet high, and alter
being bent again 1 8 0 degrees, around a 1 2 -inch pulley,
came down perpendicularly and connected to a weighing pan
(a long pail).

Different weights were added on the pan and

the cart was pulled with different speeds.

Each time the

5k

pulling force was read on the dynamometer scale and recorded.
Table 3*-, Appendix, shows the above mentioned data.

In loading

the tool cart, an attempt was made to repeat the same condi­
tions that existed in actual tillage tests.

As the results

of the tests show', there were only two pounds friction with
any test condition, which eliminated the introduction of a
correction factor in the actual data.
Tools and Equipment
To prepare the soil in the box for testing, equipment
was made to help bring the soil to the desired condition.
Two sprayer heads were installed on a piece of pipe 18
inches apart to spray the water evenly on the surface of the
soil.

The pipe was connected to the water line with a long

hose, and could be carried by hand from one end to the other
of the box.

Two heavy impermeable canvasses were used to cover

the soil after spraying, to keep the moisture from evaporating,
and also to homogenize the moisture in diiferent soil sections
by keeping the water vapor inside the soil.
A regular 20° short-tooth fork and a shovel were used
to stir the soil and eliminate the effect of previous packing,
tillage practice, and occasional cementation of the soil,
Scraper.

This was used to level off the soil in the

box and also bring it to the desired depth.

The scraper was

simply a piece of 1 / 1+ x 3 x 30 inch steel, sharpened on one
side.

Two 1 1/4 x 3/0 x 1.5 inch steol strips were used to

attach the scraper rigidly to the front diagonal steel beam

55

of tho moving cart.
with 1 / 2

Several 3/8 inch holes were drilled

inch intervals on the connecting steel strips

to control the depth. Figure, ll; shows the above mentioned
scraper.
Packer.

After leveling the soil surface, packing was

necessary to give the soil a desired apparent density.
accomplish this, a hollow cylinder with 8 . 5
and

2l
\.

To

inch diameter

inch length was mace from 2 if gauge steel sheet.

Inside this cylinder two round wooden plates were fitted
tightly.

A 5/8 inch rod was run through the centers of the

wooden plates and tightly connected to them.
as a shaft of the hollow cylinder.

This rod acted

A 28 x 3 inch rectangular

steel fram was made to hold the packing weights, and this
frame was attached to the bearings at the ends of the shaft
as shown in Figure Lj5, Appendix.

The weights on the frame

were transferred to the cylinder and caused packing of the
soil.

The packer was trailed behind the moving cart with

two liitch points .
A cement vibrator to vibrate the box was tested for
uniform packing, but it did not work satisfactorily es­
pecially in clay and moist soils.
To measure the apparent density, a four inch long
steel tubing with

one and

13/16

inside diameter was used

with one sharpened end to facilitate the penetration.

The

Reinhart method to indicate the apparent density was examined;
it was time consuming, and not satisfactory.

56

Fig. 11.

Soil box, the general view

57

Pig. 12.

Soil box, grading and packing.

58

Wtk

mm.
Fig. 13*

Soil box, the moving section

59

Pig. lij..

Tools and implements used in soil
box experiment.

6o

Fig. 15.

Attachment to the soil box to
measure the friction of the tool
carrier.

Three different implements were used to determine the
efiect of previously mentioned factors.

The implements

were of miniature size which are used mostly in cultivating
gardens; they were a four-inch plow, seven-inch disk, and
a one-inch width cultivator tooth.

To study the effect

of the size of the implement, a 2 .; inch wide tooth was
used to run the same tests and the results were compared
with the ones obtained with the one-inch wide tooth.
Soil
The uniformity of the soil in the plot was of high
importance.

To obtain a uniform soil, five cubic yards of

clean uniform washed sand (mortar sand) with almost four
cubic yards fine bottom layer clay without organic matter
(used in making tile and clay products) were used as main
constituents of the synthetic soil.

Sand and clay were

mixed with a cement mixer to any ratio that was desired.

To

get the best uniformity, clay was ground with a feed grinder
to the fine powdery form.

In mixing the soil, sand was

moistened but the clay was dry.

Full shovels of clay and

sand were thrown in the mixer while it was turning.

The

ratio of the shovels of clay to the shovels of sand gave
the clay-to-sand ratio.

After filling the box with this

mixed soil, more mixing was done by shovels and then
mechanical analysis of several points was made to ascertain
the uniformity of the soil.

Test Procedure

After the box was filled with a known uniform soil,,
moisture was added by the condensation method (spraying
and covering the soil) .

After Zl\ hours or longer the

soil was ready l or the experiment.
To break the soil clods, first it v/as thoroughly cul­
tivated with a one-inch tooth.

Then it was disturbed with

a shovel by displacing the soil from one place to the other.
To get a uniform fine particle, the fork v/as used which left
the soil with narrow ridges on the surface.

Later the

.scraper was run to level the surface of the soil.
the scraper,

After

the packer was run twice over the soil to pack

it to the desired -conditions.

After the packer, the scraper

was run again to scrape the high spots (if any existed).
this time the soil was ready for running the test.

At

The de­

sired speed was set by the speed reducer, and then the tool
was mounted on the tool cart at the desired depth.

After

each run the tool was moved along the width of the box to
a new position for another run until the entire width of the
box was used.

To start another set of runs, the above men­

tioned procedure was followed to prepare the soil for the test.
Results
Three kinds of soil material were used in the experiment:
washed fine sand with zero percent clay, 16.73 percent and
2 2 .5 2 percent clay.

63

50 -

Oh’

zo

-

L A Y -SOIL
AS H E C ' D
NO. 3

S O IL N O. 2.

5

5 0IL
Fi&. 3.6.

10
15
M O I S T U R E T E N S I O N
A T M O S P H E R E S
—*

Moisture Release Curve For The Fxp^rimenear
Soils•

Ok

CO rH
P

co
Eh

W
Eh
?H
cn

d
(UhO
a =•rH
dH
© •H
ft O
X CO

r- eo i
i
o
o

i I I
I I I

iniftcftc-• • • •
CO p NO
HD iH pH

CO■P h•
O^rftlA
rH pH

m

o

Eh

CrJ

O

CQ

W
M
Eh
M
O
fc»

©

cm

-P
d •
a> o
•g
rHS5
d pH
© *H
ftO

CM
•

1ft

CO

•
pH
pH

•
CO

eft

•

ft-

rH•
HD

p±
HD

ft

W
<0
J=»
co

XI
H

0

01

X)

XI
g
fes
W

«
Ph

id
XI

Xr
o

CO

M
M
Eh

■3 ca

-P
d
©
g-i5§
•r
d rH
© «H
ft o
X CO

p Jt

H

pj•
-ix•
-c-•
CMlftHD
CMjH

1t \

••••
ft-O CM
1ftCMCM

XI
<
a*
H

CO
&
ft

s
o
CO

co•
prHj-

Pi ­

HD

•
ft-

HD
Cf•
t

TO
©

©
p
©
(0
£
«

X)

u

CO

xo!
•H

©

CEi

cO

pH T*

•H ©
o >

CO-H
©
CD
©©
rH«
O

HD

H• pH• •
phlACft
pf-CM rH

C
MC
MC
MPh
• • • •
1ft 1ft Cft
CM eft eft

CO

•

eft

Pt"

1ft

C
M

HD
pH

rH

•
GO

pH
HD

•

•
eft

1ft

•

rH

ft

O
©

P

P

CO

d
cO

p

ft
o
©

a,

«
ft

ef•t
Cft

W

«
XI
o

O•
H

•P-P
•H*H
© *a
p(*aH
-PrHrH
d
d
cO Q O ©
P -H*Ho
©P P £
d©©P
O C
O cO d
UHrl
o.<ft cd
W
ft
~ d dA
bQ © © M
d ft £ cO
© ftO rH
o t>pi ft
d
©

•
w a•
2 2 S
•H
© a
CMCM
OO
HcO
OO
dO CM eft • ■
c
o 1
H © •eft&
O
cOP >
CD d O 1 Lf\rH
•H © 0 o ©
d CD<£ CM •CQ
cd d
XJ ©
p
o ft
P
©
&

Pi
cd
CD
tsO
d
•H
xs
pH
O
£3
d
©
p
cO
^ p
d
a©
Po
•aH ©
X ft
©

S

p
d
©
rH
©
•r
r>
H
P
o*
©
p
©d
d©
P CD
Pw ©
d
•H ft
O
s

ra
©
d
©
X!
ft
©
o
pa
©
HD

P

ra
©
d
©
-d
ft
©
o
a
p
©
ift
H
P
eft;
p
©d
d©
P o
P d
ra ©

p
©d
d©
P CD
P© d
©
•H ft • h a
o
O
S
S

©
©
©
d
r>>
d
O
d
•H
©
P
©
©
d
PP
rap
•H d
o©
aO
d
r
H©
•H
o
CO

ft

ft
ft
cO

©

d
CO
d
's
©

e
©

d

P
©

©

©

d

ft

©

*

65

higher clay percentage soil was also tried but be­

a

cause ol dilficulty of' handling (easy puddling; the test
was discontinued.
The mechanical analysis (7) of the soil

Particle size

was:

Percentage

2
- .053 num.
.053 “ .0 0 2 m.m.
below
.002 m.m.

3 I .3
3 ^ .1
3^.6

Four speeds of tool movement were selected and used
throughout the experiment,
r.p.m. of the drum
1)
2)
3)
4)

feet/min

58
90
125
170

53.1
82.5
111+.5
155.5

miles/hour
.60 h
.938
1.275
1.77

With the limited selection of speed reducer, dynamometer
scale, and the length of box, a higher speed was not prac­
tical .
The pecking force was provided by adding pieces of
channel beams, each weighing nine pounds.

The three sets

of weights were 3 6 , %l\.> an8 79 pounds; in the case of sand,
one 18-pound packing force was used.
The moisture percentage could not be controlled as
closely as the other factors.

To obtain a particular

moisture percentage the method of trial and error was used.
After some experience the approximate amount of water neces­
sary to bring a soil to a definite moisture content could
be estimated.

' f
oo

3.83% MOl 3TO R e
2.<J8 7. M OlSTUf\E

5 4 *

PACKING

<0

s.
*
k

63%

MOIST U RE

*

C.P

6

M O t S T U R E

Ml 10

3 G 4* P A C K I N G . F O R C E

is;

<3
Ul

5

It
k
It is

<t
It

3.83 y

MO/3TC! RE

2 .P a y

MOISTURE

Q
10

IQ#

P A C K I N G

F O R C E

3 -

—r-

/.

Fig. 17.

—

US

r-

2.

S P E E D
M , P. H — ♦
Speed versus draft requirement of a one-inch tooth
in soil No. 1 (99 percent silt) with two different
moisture percents, three packing forces, at I;-inch
depth.

20 i
3.9CZ M 0 I 5 T U R £
2.82 7. M 0 I 5 T U R E

15 -

10

-

54#

PACKING

FORCE

t
ri 18 -

3.°lbV. M O I J T U R E
2.62

2
r*

*/. M O I J T U R E

IS -

F
2
UJ 1 0 -

3 6 #

PACKING

FORCE

1
UJ
DC
3
a 20 w
%

3.°ie> 7; M O I 3 T U R E

p
IL
<C IS <r
o

2 , 8 2 7. M O I S T U R E

18#

P A C K IN G

FO R C E

10
TV

I.
S P E E D

Fig. 18.

l-S

2.

M . P. H. —*•

Speed versus draft requirement of a four-inch
plow in soil N o . 1 (99 percent silt) witn two
aifferent moisture percents, three packing forces,
at 2 . 5 inch depth.

68

35 -

lbs. Packing force

Packing force
30 lbs. Packing force

2.5

(3.77Z W O / 3 T U R G

23

">30

4)

^

79 lbs. Packing iorce
-Lbs. Packing force

ID'RAFT

RSQUi'R^rnerts/'T

1 5 -j

lbs. Packing Iorce

M O I 3 T U K 5
21

20
79 lbs. Packing force
Sbr lbs. Packing force
30 lbs. Packing force

f5 -

M O t J T O
io

R E

-

I 2 -

ij ctiid 9l|- lbs. Packing Iorce
r>

I0 -

8

----------- 3b o.bs. Packing iorce

-

— r~
15
Fig. 19*

T

I.

1.5

— r~
2

.

3 P E E O

M. A?H,

Speed versus draft requirement of a one-incu tootn
in soil No. 2 (ic. / poreent tiuj) wit a four nil - .r<mo is ture percents , onroo yacking 1 crocs , at ip-i.icn
depth.

69

45-1

lbs. Packing force
lbs . Packing force

40 -

lbs. Packing force

t
e<?/

35-

I3 .7% M O I3 T U R E

33 -

/si
i N 3 W 3 ^ / n o 3 M .

79 lbs. Packing force

30 -

lbs. Packing force
36 lbs. Packing force

25 -

20 -

79 l bs . Packing force
* & a

23 20 -

17 -

5 5>4 l b s . Packing force
36 lbs. Packing fore

q. I S % M O I 3 7 U R E
1

2.5

Fig. 20.

-5 P E E D
P. H.
Speed versus draft requirement of a four-inch plow
in soil No. 2 (16.7 percent clay) with three different
moisture percents, three packing forces, at 2 .5 - inch
depth.

70
5 o \f
79 lbs. Packing force
h

2

4 5 iy

£
UJ
or

30 lbs. Packing force

40 3
0
14

I-

45
- 35

Ll

<

40

54°l b s • Packing force

IN

Ib 3

79 l b s . Packing force

REfliUIREMEWT

l b s . Packing force
35

1, 5 6 * / ,

30

79 lbs
Sk lbs
36 lbs

D R A FT

25

20

M O IS T U R E

-

o
16 -

.5

Fig. 21.

9.A '/. M 0 I5 T U R E

».
1*5
2.
5 P E E D
Speed versus draft requirement of a 2.5-inch tooth
in soil No. 2 (16,7 percent clay) with three dif­
ferent moisture percents, three packing forces, at
!|-inch depth.

k-eo

■5° J.

Moisture

12,^6 X

71

_Q
79 l b s . Packing force
45 H

z
UJ

-40
54 l b s . Packing fore

5
U)

O'
D

)b3 .

0

tlJ

36 lbs . Packin,

-35

force

q:

|M

K

DRAFT

K E O U l R E M E N T

q. & 3 X

<c
0:
-3 0
Q

M OI^TURE

79 l b s . Packing for

54 l b s .
15 -

Packin^^'''"'^
force
36 lbs. Packing fore

14 -

1 .2.5 X M O I S T U R E

All three packing forces

IO -

1---------- 1---------- 1---------- r
.5
i.o
f.5
a.

-SPEED
Fig. 22.

N/L R

H, — ♦

Speed versus draft requirement of a one-inch tooth
in soil No. 3 (22.3 percent clay) with three
different moisture percents, three packing forces,
at 4 “lncb depth.

72

45

79 lbs • Packing force
-

54 lbs. Packing Iorce
3o lb s . Packing force

40 -

35-

(2.21 /, M O I 3 T U R

Ib S

31 -

79 lbs. Packing force

D R P t F ’T

R e Q U / R £ f>n £ M

T

IN

30

54 lbs . Packing force

ZS36 l b s . Packing force

2.0

-

9. 7 4 / .

M O / J T U K E

I5 ~
All three packing forces

20

-

7,66 y. M O I S T U R E
IS -

f.
Fig. 2 3 ,

“T ~
/.5

■SPEED
M . R H. -+
Speed versus draft requirement of a four-inch olow
in soil No. 3 (22.5 percent clay) with three different
moisture percents, three packing forces, at 2.5 inch
depth.

73

SO 79 lbs. Packing force
4 5-

55- lbs. Packing force
3 6 lbs. Packing force

40 -

35-

Z
ui

12.79^ M 0 1 3 T U P E

5 32

id
Of
3
lbs. Packing force

<* 3 5
UJ
K

lbs. Packing force

!•

lbs . Packing force

lL 3 0
<
k

0

25 -

10.32V.

M 0 1 3 T U T ? E.

20 1I
I*
/. 5
2.
5 P E E D
Mi. P. H . - ♦
Speed versus draft requirement of a 2.5-inch tooth
in soil No. 3 (22.5 percent clay) with ;two different
moisture percents, three packing forces, at lf-incb
depth.

~

•5

Pig. 2k

\-4o

74

79 lbs . Packing
force

35

acking force

36 lbs. Packing force
h^5

\ d . ~ l *A

MOISTURE

19 l b s. Packing fore

t 3 0 —\

DRAFT

REQUIREMENT

IN

lb3.

2LO

lbs. Packing force

36 lbs. Packing force

15

-\

10

79 l b s . Packing force

f- I0

5 4 and 36 lbs.

Packing forcd

S . ay.
7

ST

I.

5PEED

moisture
1. 5

2.1

M. P. H , -

Pig . 2 5 .
____ disk
___
Speed versus draft requirement of
on-iach
in soil Wo. 3 (22.5 percent claj/j with throe different moisture
per cents, three packing forces, at 2 .g-inch depth.

75

Wi t h e a ch soil mixture experiments were run for three
different soil moisture contents.
content,

With each moisture

three different packing forces of soil were selected

to be tested.

Four different speeds of the tools were run

with each pa c k i n g force of the soil.

In this way a total of

108 readings were recorded with each implement,
the case of sand where it was not necessary.
are recorded and given in Tables

except

in

The results

6 through 3 0 , Appendix.

Conclusions
In general the results obtained were largely qualitative
rather than quantitative.

The readings of the scale in higher

speeds and loads were not very accurate because of the v i br a­
tion of the dynamometer needle.

A hydraulic type dynamometer

w i th a re cording system would work better than the present
spring dynamometer.

Also,

to get more accurate results more

tests w i t h different clay and moisture content were necessary.
This, however, because.of time and fund limitations, was not
possible .
The introduction of the theory of "models and similarity"
and its application to the soil box and miniature implements,
to be discussed later, not only will prove the validity of
these tests, but also will encourage
tory methods

in tillage problems.

The effect of s p e e d .
y = ax'3 / c

the use of' small labora­

can represent

The general

equation of

the relationship between the

speed and the draft requirement of tillage tools.

76

zo

& Pa

c k

t

f o r c e .

'REQUIREMC^T

tN

tb3<

79

1.77 m.p .h.
1.29 m.p .h.
.94 m.p.h.

.60 m.p.h.

#

PKCKINtr

FORCB■

07*f\FT

54

1.77 m.p.h.
1.29 m.p .h.
.94 m.p.h.

.oO m.p.h.

p a c k in

t0

10

Fig. 26,

Or

f o r c e

ao

cc

a y

/

Percent clay versus draft requirement of a one-inch
tooth with 10 percent moisture, four speeds, and
three packing forces, at [{-inch depth.

-40
7 9 #

PACKIN4

F0nee
-30

• ZO
1,77 m .p .h

1 , 2 9 m.p.h. n

54#

PACKtMC

FORCE

-40

36#

PACKING F O R C E
- £0

— i—

I0
Pig. 27.

2.0

Percent clay versus draft requirement of a one-inch
tooth wit h 13 percent soil moisture, four soeeds,
three packing forces, at ij-inch depth.

36

#

PACKING

FORCE

30

20
5 4

#

PACKING

FORCE

T* E G>U t RE

P7ENT

IN

/LS

1.77 m.p.h.
1.29 m.p.h.
. 9 4 m.p.h.
. 6 0 m.p.h.

1 . 7 7 m.p.h.
1 . 2 9 m,p.h.

30

.94 m.p.h.
. 6 0 m.p.h.

PACKING

FORCE

DHRFT

20

do
Fig. 28.

'A C L A Y
Percent of clay versus draft requirement of a fourinch plow with 10 percent soil moisture, four speeds,
three packing forces, at 2 .5 -inch depth.

79
1.77 m.p.h

40

1 . 2 9 m.p.h.

.9 i+ m.p.h.
. 6 0 m.p.h.

30

36

20

#

PACKING F O R C E

■50

* 1.77 m.p.h
1.29 m.p .h. ■40
fbJ.

.9 ij- m.p.h.

/A/

. 6 0 m.p.h.

30
PACKING

UfR E M E N T

5 4 #

FORCE

1 . 7 7 m.p.h.

20
1 . 2 9 m.p.h.

fi EQ

•9k m.p.h.
. 6 0 m.p.h.

FT

30PA K I N G

FORCE

ORA

7 9- #

0

I0
Fig. 29.

ao

Percent clay versus draft requirement of a four-inch
plow w ith 12.2 percent soil moisture, four speeds,
three packing forces, at 2 .5 -inch depth.

80

As the curves of draft versus speed indicate, this
relationship is an almost horizontal line in sandy soil
and in any other types of soil that have low moisture con­
tent and where the effect of cementation has been eliminated.
The maximum moisture content at which the speed does not
have appreciable effect is slightly aoove the wilting point,
or moisture percent of almost 15 atmospheres.

As the amount

of moisture and clay increased, the slope of the line in­
creased so that in very high clay and moisture contents the
relationship changed from a straight line to a curve.

This

change can be shown in the general equation of y : ax"*3 / c
by the different number given to

b.

For example, b - o, y

is a straight horizontal line, and for b = 1 , this will be
a straight line with variable slope.
Also the kind of implement seems to have an effect on
the relationship between the speed and draft.

For example,

with a disk the curves show straight lines even at 2 2 . 6 per­
cent clay and 12.7 percent moisture content.

Probably the

change of curve will occur in higher clay and moisture per­
centage .
Effect of clay content.

By clay content is.meant the

percentage of particles that are smaller than two microns.
Figures 26 through 29 show the effect of clay percentage on
the draft requirement with constant moisture, speeds and
packing force.

As the shape of the curves indicates, the

clay content has very little effect in low7 moisture percentage,

31

1*77 m.p.h
1.29 m.p.h

30

-

20

-

•94 m.p.h
.64 m.p.h

FORCE

*79#

10 -

1.77 m.p.h
1.29 m.p.h
•94 m.p.h

30 ~

. 6 4 m.p.h

/ /V

f £>3.

t

-

5 4 * PACKI NG, F O R C E

10 -

30 -

DPR P

T

K £ Q ( J / ^ e M £ N T

20

20

-

3&#

(0

PACKING FORCE

-

, 0

1’lti® 30*

15

% n o t S T U R E

-*

Moisture percent versus cirai t r e q u i r e . , o l

a
one-inch tooth in s^ii 11>. 2 (lu.7 percent cia;-)
with three packing iorees, iour
, at
c ep th.

1,77 m.p.h

82

1 . 2 9 m.p.n

40

~

m.p .n
m.p .h

30 ~
79

F RACKING

FORCE’

20 “
1 . 7 7 m.p.h.
1 . 2 9 m.p.h.

t 40 4
94 m.p.h
60 m.p.h

*)
4)
Z
“ 30
h

z

5 4 #

PACKING

FORCE

y

I20
y
Be
^ 40
6
u

1 . 7 7 m.p.h.

1.29 m.p.h.
,Q1;. m.p.h.
• 6 4 m.p.h.

tt
k
u. 3 0
fc

36 #

PACKING.

FORCE

Q

20

£
Fig. 31•

^

,!y

^ M W J T U R E - .

Moisture percent versus draft requirement of a
four-inch plow in soil ho. 2 (1 6 . 7 percent clay)
with three packing forces, four spotis, at 2.3inch depth.

S3

50 ~

1.77 m.p.h

40 m .p .h

IN

1b».

30-

K E O U I R E M E H T

20

7 9 #

-

PACKING

FORCE

50-

D R AFT

1.77 m.p.h.
1 . 2 9 m.p.h.
•9 [j. m.p.h.

40-

. 6 0 m.p.h.

30-

20

C K lN G

-

Fig. 32.

F O R C E

X. M O I S T U R E
-►
Moisture .percent versus draft requirement of a
2.5-inch tooth in soil No. 2 (16.7 percent clay)
with two packing forces, four speeds, at 4 “Inch
depth.

SO- 7<*# PACKING FORCE

84

1.77 m.p.h

40 _

30-

1.77 m.p.h

50

1.29 m.p.h. „ 4 0 h
0

_

5 4 #

PACKING

FORCE

-30

1 . 7 7 m.p.h.
1 . 2 9 m.p.h.
uj

40-1
. 9 4 m.p.h.
. 6 0 m.p.h. - 1 0 o
3 6 #

10

P A C K I N G

F O R C E

-

M O

10 T I I R

£ *

IS

'Fig. 33. 'Percent moisture versus draft requirement of a
one-i nc h tooth in soil No. 3 ( 22
percent clay) wi th three
pa c ki ng forces, four speeds, at 4 “ in °h depth.

35

1,77 m.p.h.
1.29 m.p.h.

h 40
. 9 4 m.p.h.
. 6 0 m.p.h.

- 30

-

43 - 1

tt P A C K I N G F O R C E

20

1 . 7 7 m.p.h.

t 40 Ib2.

1 . 2 9 m.p.h.

IN

. 9 4 m.p.h.
. 6 0 m.p.h.

20 -

QU I RE

M

£ N T

30 -

5 4 #

PACKING

FORCE

R£

1 . 7 7 m,p.h.

1 . 2 9 m.p.h.

O RAFT

40 -

. 9 4 m.p.h.
.6 0 m.p.h

30 -

20

-

G K IN G

FORCE

IS

|0
V. M O I S T U R E
—
Pig. 34. Percent moisture versus draft requirement of a
four-inch plow in soil No. 3 (22.5 percent clay)
with three packing forces, four speeds, at 2 .5 -inch
depth.
5

36

50
1 . 7 7 m.p.h

40-

20

-

R £ <3 u I R E MEN

T

|M

I bJ3

\ 30-

7 9 #

P A C K IN G

FORCE

1 . 7 7 m.p.h.
1 . 2 9 m.p.h.

4 0 -

,94 m.p.h.
.60 m.p.h.

DRAFT

30-

2.0
k iw g

T

S
Fig» 35•

f o r c e

--- 1-------------------- 1—

10

IS

'/. M O I S T U R E
Moisture percent versus draft requirement of a
2.5-inch tooth in soil Wo. 3 (22.5 percent clay)
with two packing forces, four speeds, at 4 ~inch
depth.

-

40

\

87

_D

- 30 I2
UJ
S
Ui
u

□
0
UJ

40 -

F O R C E

Ji

IO K
k
lL
<c

O'
Q

30 h

2
UJ

2 20
UJ

O'
0

54#

& 10

PACKING

F

UJ
tt3 0
h
II

6Cm

«

&

ift * P I t>
iI

*9^4- iii *p «ii •

m *_p•11 •

a io
a

to

3 6 #

P A C K I N G

F O R C E

“ I------- 1--------------- 1
7-5
10
15
7o M O I S T U R E
P ig .

38 •

M o ia iu i'b

p o rce n t

ver&u&

-►
C i'& i U r ~ c .u ii*~ :u -iit,

ui

s.

s« veil-inch 'aist, in &011 i<o. 3
•> percent
J
Wibii ux^-i ut peeking 1 ore us , i -i r t pe&ds, et i.p —
Xi C
,JJ
, C
. ti

L
ti.i. •

88

but by increasing the moisture, the curves of draft versus
clay rise rapidly.

This increase will continue to a m a x i ­

mum wh ic h is around field capacity, and after that it will
tend to a slight decline
is logical because

(refer to moisture c u r v e s ) .

This

the capillary activities of the clay p a r ­

ticles will end at aoout moisture equivalent.

Two sets of

curves have been drawn for different implements under two
different moisture contents.
kpply ln & H

cases.

The above mentioned changes

The exact equation for the relationship

bet w ee n draft and clay’ content can not be given here b e ­
cause there were not enough points in the curve,

but in

general,, they are of the type y * ax*5 / c, where,
cases,

in most

c = 0.

ifffect of m o i s t u r e .
portant soil factors

Moisture is one of the most im­

that have been observed in this experi­

ment to affect the draft.

However,

cause of the lack of effective

in the sandy soil, b e ­

soil particles,

the change of

moisture has little effect on the soil resistance,

but by­

mixing some clay wi t h it the oifect of moisture was noticeable
In almost all cases

the curves

start with a sharp increase

and then f lat ten around the moisture content of field

capacity

The.moisture equivalents for both clays have be en indicated
and can be noticed very distinct],;,
clay contents,

In higher

the increase of moisture caused a very bao

pudd li ng of the soil which made
soil.

on the curves.

it diificult to work the

The limits of moisture variations within w h i c h soil

89

4o 1 . 7 7 m.p.h.
1 .29 m.p .h.

30

•9 i+ m.p.h.
. 6 0 m.p.h.

2.0

-

Z

13.77

M 0!3TU R £

1.77 m.p.h,
1.29 m.p.h,
•9 q m.p.h,
,oO m.p.h,

e q

e

30 -

u in

m

e nt

ta/

tbs

t

20 I I . 1 5 7.

ZO -

M 0/ JT UH £

1.77
1.29

.94
I0 -

iO X

M

q. 3 6%

01

M O t J5TU1R £

1--------- 71---------- 1---------- 1---------- 1
0
ZO
40
GO
QO
PA C K IM &
FOR C £
iN U 3 .
—*
Fig. 37. Packing force versus draft requirement of one-inch
tooth in soil Wo. 2 (16.7 percent clay) with four
speeds, four different moisture percents, at l^-inch
depth.

90
50 1.77 m.p.h.
1 . 2 9 m.p.h.

AO -

•94 m.p.h.
. 6 0 m.p.h.

30 -

/AJ /

.

f

1.77 m.p.h.
1 . 2 9 m.p.h.
.9 I4. m.p.h.
. 6 0 m.p .h.

DRAFT

REG
> UI R E t*) E.N ~T

30 -

ao -

2.S-

1.77 m.p.h.
1.29 m.p.h.

ao -

. 9 4 m.p.h.

*oO m .t>.h .

15 -

q . / S */.

ao-----Fig. 38

r

"T“

r-?0 /5 T U R £

PACKINCr F O R C E
40
60
Packing force versus draft requirement of e fourinch plow in soil No, 2 (16.7 percent clay) with
three different moisture percents, lour speeds,
at 2 . 5 inch depth.

91

60

-

50
a
/Q
>

*n

H40
7)
m

P
1 2 . 9 B'A M O I 5 T U R E

C30

7)
m

I
1.77 m.p.h.

ro^o

z

■
1 . 2 9 m.p.h.

4

.oO in.p .ii.

•94 m.p.h.

Zio

-

9. 8 3

£

MO/ 5T U R E

0"
u
20 -

lor all speeds

10 7. 2 5 X

20
PACKING

Fig* 39*

40
FORCE

M O I J T U R E

IN

60
Ib5.

&0
—♦

Packing force versus draft requirement of a
one-inch tooth in soil h o . 3 (dh.p percent cl&p)
with three aifforent mois turn percent!, 1 our
speecis, at ip-inch aeptn.

92

451.77 m.p.h.
40 -

1 . 2 9 m . p.h.

30 td.et

V.

1*10 1 3 T U R E

ORPtFT

"REQUIRE

M£WT

/N

f ±3.

.9^- m.p.h.
. 6 0 m.p.h.

1.77 m.p.h.

30 -

1 . 2 9 m.p.h.

.91+ m.p.h.
.60 m.D.h.
20

-

9 . 7 4 X

M O 13 T U R E

Io - 1

25 -

All four speeds
20

-

7. 3 Q X f * I O / 3 T U R E

/5 -

2 o

~1---------- 1
40
60

P f t C K I hJ G
Fig. ij.0.

1---

— r

60
P O R C £

100
/A /

/&.S

Packing force versus draft requirement of a
four-inch plow in soil No. 3 (22.5 percent clay)
with different moisture percents, four speeds,
at 2 .5 -inch depth.

1,77 m.p.h

30

-

2 9 m.p.h

94 m.p.h.

20

-

60 m.p.h

10-

IO.^q/, M O I S T U R E
1.77 m.p.h.

40-

1 . 2 9 m.p.h.

IN

lb 3.

t

.6 0 m.D.h.

30-

20-

12.7

X

M O I S T U R E

V.

1.77 m.p.h.
1 . 2 9 m.p.h.
.94
*6o m.p.h.
M . 0 I 3 T U R E

OR

<
4 FT

R E fiU IR E M E N T

.9 4 m.p.h.

15 H
0 -

S .6 3

5 ~

2 *0

4*0
P A C K IN G

Pig. 4 1 .

6*0
F O R C E

~3~0
IN

I b5.

Packing force versus araft requirement of a scveninGh disk in soil No. 3 (22.5 percent clay) with
three different moisture percents, four speeds,
at 2 . 5 inch depth.

91+

was workable for tillage operation,
increase of clay percentage.

narrowed down w if n the

For this reason,

the tests

w i t h the soil having 3^i-»8 percent clay were not feasible.
The soil wi th 1 6 .7 8

percent clay could be worked even after

1 1 ,73 percen t moisture content which is the moisture equiva­
lent of this

soil,

but in the other side,

the soil with 22.52

percent clay w a s i n a very bad shape with 12.7 percent moisture
whi c h is less than 11+.83 percent,
that soil.
obtained

the moisture equivalent of

The best equation that could represent the data

in all cases

is

<t + b*
#

= -e

-t- C

Effect of packing f o r c e .

The packing force of the soil

changed the apparent censity of the soil.

The relationship

be tween the apparent density and compression force has been
studied by Hichols and was discussed previously.

The density

change in different tests has been shown In the tables given
for each test.

It seems to be more practical here to show the

relationship between the draft and the force of packing soil.
As the m e t h o d of packing was the same throughout the experi­
ment,

it was decided to use the amount of weight applied over

the packer as the abscissa and the draft of the implement as
the ordinate.

The change of draft was proportional to the

change of packing force,
line in all cases.

and this relationship

is a straight

95

Theoretical Study of Soil Factors Affecting The
Draft Requirement of Tillage Tools
Reasons for Study
The problem of soil resistance against the pulling
of a tillage tool should be studied by the method of di­
mensional analysis for two reasons:
1)

Instead of running field tests to indict,' the

performance of a particular tillage tool, the performance
can be found with small models in the soil box inside
the laboratory.

Then by the use of the theory of models,

the results of laboratory tests can be applied to the actual
field size,
2)

The theory of dimensional analysis is a good method

of finding an equation indicating the relationship between
the soil resistance against the tillage tools and the differ­
ent factors, or a dimensionless product of these factors.
General Remarks on Dimensional Analysis
An equation will be said to be dimensionally homogenous
if the form of the equation does not depend on the fundamental
units of measurement.

Dimensionally homogenous functions

are a special class compared to the general types of functions
that are investigated in mathematical analysis.

The theory

of dimensional analysis, which is the mathematical theory of
this class of functions,

is purely algebraic.

96

The application, of d iruens ional analysis to a practical
problem is based on the hypothesis that the solution oh the
problem is expressible by means of a dirnensionally homo­
genous equation in terms of specified variables.

an un­

known equation is dirnensionally homogenous when the equation
contains all the variables that would appear in an analytical,
derivation of the equation.
The first step in the dimensional analysis of a problem
is to decide what variables enter the problem.

If variables

that are introduced do not affect the phenomenon,
terms may appear in the final equation.

boo many

If variables that may

affect it are omitted, the calculations may reach an impasse,
or an erroneous answer may be obtained.
Theorems:

1)

A set of dimensionless products of given

variables is complete, if each product in the set is inde­
pendent of the others and every other dimensionless product
of the variables is a product of pov/ers of dirnensionless pro­
ducts in the set.
2)

Buckingham's Theorem.

If an equation is dimen-

sionally homogenous, it can be reduced to a relationship
among a complete set of dirnensionless products.
3)

The number of dimensionless products in s complete

set is equal to the total number of variables minus the
maximum number of these variables that will not ionn a dimen—
sionless product.

n

wxon tue present Knowledge ol soil characteristics,
the elements that have been considered effective In the
resistance lor-ce against tillage implements are sheer, ac
celeration of tool, velocity of tools, density of soil, a
unit of length which is effective (it can be first, second
or third power ~of length), and viscosity of soil solution
or water in soil.
The dimensions of the above factors will be
Shear strength

S =

F
L2

Acceleration

A =

L

Velocity

V = L
T

Dens ity

F

Force
Length

D = L
FT

Viscosity
According to
be said that f(

The force of soil resis­
tance against tillage tools

the theory of dimensional analysis,
A k
c
*
&
*
*
5 >A . , \/ , (* ,Q ?
D, A i ) = 0 .

According to Buckingham’s theorem this
set of dirnensionless products.

it can

can be reduced to a

The number of those products

is equal to the total number of variables minus three (the
number of independent variables).

To find the dirnensionless

98

products a fev; assumptions should be made so that each
product contains only one of the required unknowns;

F ir 3 T

l)

Assumption

fc> = C * d =

O

Q
F
L
T

D )= 0

9

0
- 2.
0

6
O

I
o

OR /[(£)* (F)*(L)#]=0
C L 4- e. =■ 0

OR

-2. CL4-f =. o

F

50,

OR

£=t-l ;

or

OL = /

AMD

(

}

J

a=-£

/ = <2

=0

®
2)

/s A 0/MffA/ilD/VLFS5
PROOUCT

S ECONP A J J U M P T t O M
CL— b s g s . 0

Ki /v
0R

£ ^ cf

(9

D

/ C ( f ) e (

^x

W

)- o
C

F ) ' ( * • ) " ] -

Q D
d + & = o
c— 4 d

F
L

ss> o

T

0
1
-I

I
2

o
0

0
I
0

— c+ 2 d — o

jo,

FOR

€ = -!

dUl

Ctz - 4 + $ =- o
AND
C-

OR

C+-f=4

ad m£.

t

f=2

£ >x
^2
/ (v V
0
t> ) = o
v £S > l ? \
13 * o t M E N J i O N L E J J
— g
) - 0
P R O D U C T

K

99

3)

THIRD

fl^U M pTIO N
01 = b ssd =. O

0

R
f [ ( r ) C ( i ? ) V > e ( L )f ] = C>

V

M
/
F 0
L 1 -2
1
T -1

3 + e =°
c " ,a3 + / = 0
-C + g = c
for

3

0

e = -\

•

? C- I AMD

4)

FOURTH

t

Q

D

1
0
0

0
1
0

frl

[

b

t

'

ASSUMPTION

(

$

f

(

'

W

]

~

A P
1
F O
L 1 -4
T -2 2

d + e = o
b — 4 cL+ 4 — o
— 2 ^ +£cls o
FOR
JO,

1
0
0

D
0
1
0

IS A D I M E N 3 I O M L E S 3
PRODUCT

>

•*

Q

£= -I

f

,

oL-

(° ^

I

;

j)S l

AND

f - 3

D ~3

IS A D I M E N S I O N L E 3 3
PR OD U C T

F I N A L L Y

f [(^0;

(v9#)» ( a P d "
3)

O R»
t (-#rr)+» c^
*

OR

o

+ £< 4 * ) + 6

100

io find the amount of
£.nd

&

which is a function of S, D, Vf p

, the coefficients of A, B, C, and

Cr

should be

de te rm i ne d fr om practical data.
The relationship between shear and moisture-and clay
content lias been indicated by ifichols, and has been di s­
cussed here previously.
is zero,

The acceleration of the implement

if it will run wi th constant speed; when accele ra ­

tion is zero,

the last item will drop out.

The effect of

viscosity should be studied more and its relationship to the
percent of clay and moisture should be determined.

The

velo cit y and the size of the implement also the density of
soil can be measu red directly and used in the above equation.

Conclus ions
E qu ati on

( f ) will indicate the amount of resistance

force of the soil against the pulling of the implement.
This will be

justified only when the soil is uniform and under

controlled conditions.
of the factors
matter,

As has be e n discussed before,

some

that it is not possible to control like organic

vegetation,

etc., have b e e n eliminated;

some laboratory

work is needed also to indicate the constants and the degree
of effectiveness of the vi scosity and its relationship with
the other more easily measurable soil properties.
-it could be me nt io ne d that

this is not a complete theoretical

solution for the pr obl em of measuring
of tillage.

In general,

the craft requirement

It indicates only the possibility of the theor et i­

cal soluti on w h i c h should be investigated later.

101

Upon the
u n i f o r m soil,

completion of the above relationship for the
it can be applied to field conditions by m u l ­

tiplying this relationship by certain factors which will be
determined according to the field
has b e e n used

condition.

This method

in many other fields of applied science,

and

will be d is cus se d further in the section on "Suggestions
for Further St ud y. ”

SUMMARY

The non -uniformity of soil,
control of soil properties
possible,

and the fact that the

in the f ie ld is next to im­

has made field tests of very little value.

of the fiel d tests run in different localities
duplicated,

None

could be

and no uniform plot existed to use for the

experiments.

Haines

(3Z4.) in England,

also recognized this

non-uniformity of soils in field tests.
In order to study the pr ob le m of the draft requirement
of tillage tools,
first.

the important factors were determined

Thai, w it h the help of laboratory methods,

the rela­

tionships be tw ee n the draft requirement and the effective
factors were determined.
The theoretical method was the best way to determine
the above me n ti on ed r e l a t i o n s h i p s .

The application of the

theory of dimensional analysis to this problem seemed to be
satisfactory,

though more investigations are needed to obtain

the final results .

More detailed conclusions are given at

the end of each section.

SUGGESTIONS FOR I URTIIER STUDY

Changes

Proposed Changes

in Laboratory Tests

in Building Experimental Soil Box

A longer and wider soil box would make possible tests
w i t h higher speeds and also more runs with different speeds
wh ic h could be done after each soil preparation.

The depth

of the box seemed to be adequate and no changes were needed.
The l e n g th of the tool cart should be increased to have more
stable

smooth movement of the tool cart at higher speeds.

A hydraulic dynamometer w ith recording instrument would
increase

the accuracy of reading.

Change of the trolley door tracks to a stronger and more
rigid type,
speeds.

would avoid

the bouncing of rollers at higher

It should also be designed so that it will always

remain clean and save time by eliminating continuous
cleaning.
Some other small changes which might be suggested are:
providing a means of stirring the soil instead of using a
hand fork, usin g a better method to measure the apparent
density,
the test.

in order to save time and increase the accuracy of

io 4

More Tests With Different Conditions
Only three kinds of soils were used in. the experiment.
The above soils were made of only sand and clay .

For better

results the number of soil mixture's should be increased.
Also organic matter, and vegetation can be added to the soil
in known quantities, and their effect on the amount of draft
determined.
More Theoretical Study
The theoretical method should be developed more com­
pletely and checked with the laboratory results.

The method

of dimensional analysis seems satisfactory, though some
other methods might be found that are more adaptable.

In

the theoretical analysis, the conception of the main func­
tions of tillage is very important.

Any misassumption of

the factors presenting those functions will end in a faulty
result.

Therefore, those function, the assumptions, and the

solution of the equations should be studied carefully.
Application of Theoretical and Laboratory
Results to Field Conditions
As has been mentioned before, the main difficulty in
field tests is the non-uniformity of the soil.
this difficulty,

To overcome

the author suggests consideration of the

following method:
1)

Developing a method for the classical study of the

105

effect of some factors such as different organic matter,
surface vegetation, root system, trash, etc., in the
draft requirement of functionally different tillage im­
plements .
2)

Using a large sample of the non-uniform soil,

mixing it thoroughly and running different tests in the
soil box.
3)

Running a few field tests and getting the average

amount of the craft requirement.
if.)

Determining the ratio of the result of the field

test to the laboratory test.
factor."

This can be called the "field

Determining and recording the field factor in a

few soil types .
5)

Determining the soil type and the amount of various

effective factors, as has been previously discussed, in order
to discover the draft requirements in any field.

This would

require the use of the theoretical equations to evaluate
the amount of theoretically required draft, and by multiplying
by the field factor would give the actual draft requirement of
the tool.

APPENDIX

106

TABLE

VI

DRAFT REQUIREMENT OF A ONE-INCH TOOTH
Soil No. 1
Moisture percent
Run
No.

Packing
P'orce

Apparent
Density

lbs.
18

k

11

1
2
3

38
ti
11
11

1.35
i»
n
ti

1
2
3

5kw

1.39
ti

k

t

h

it
ti

Speed
m.p ,h.

1
2
3

11

2 .9 8

1.29
11

n
it

11

n

.6 0

.93
1.29
1.77
.6 0

.93
1.29
1.77
.6 0

.93
1.29
1.77

Draft
Requirement
lbs.
11.
10.5
11.
13.
10.
10.
1 2 .5
13.
10.

11.
1 1 .5

*

107

TABLE

VII

DRAFT REQUIREMENT OP A ONE-INCH TOOTH
Soil No. 1
Moisture Percent
Run
No.

Packing
Force

Apparent
Density

lbs.
1
2
3
k

18

l
2
3
k

36

1
2
•5

k

ii

Speed
m.p .h.

1.31
ti

H

it

n

it

it

3.83

1.32
it

it

it

it

ii

1.37
I*

it

n

ti

rt

ii

.6 0

.93
1.29
1.77
.6 0

.93
1.29
1.77
.6 0

.93
1.29
1.77

Draft
Requirement
lbs .
11.
10.
12.5
13.
12.

4.
4-5
10.
12.
13.5

4.5

108

TABLE

VIII

DRAFT REQUIREMENT OF A ONE-INCH TOOTH
Soil No. 2
Moisture Percent

Run
No.

Packing
Force

Apparent
Density

lbs.
1
2

18
11

11

3
4

11

11

11

ti

1
2

36

•3

k
1
2

5

I .2 3

1 .2 6

11

11

H

ti

II

11

iT
it
ti

1.27
n
11
11

9 .3 6

Speed

Draft
Requirement

m.p.h.

lbs.

.6 0

10.

.93
1.29
1.77
.6 0

.93
1.29
1.77
.6 0

.93
1.29
1.77

9.
9.5
10.
10 .
11.
10.
10

.<

1 0 .5
11.
11.
1 0 .5

TABLE

IX

DRAFT REQUIREMENT OF A ONE-INCH TOOTH
Soil No. 2
Moisture Percent 10.0

1
2
7

i
2
3
4
1
2
3

£

Packing
Force
lbs ,

36
>i

Apparent
Density

1.22
a

ii

it

it

it

It
>i

It

tt

It

79
n

Speed
m.p.h.

h~>
a
KjJ
o

Run
No.

1 .3 2
it

it

it

M

it

Draft
Requirement
lbs.

.6 0

12.

.93
1.29
1.77

*?•
Ik a
15.

.6 0

.93
1.29
1.77
.6 0

.93
1.29
1.77

12.5
13*
IE.
16.5
15.
16.
19.
17.

110

TABLE X
DRAFT

REQUIREMENT OF A ONE-INCH TOOTH
Soil No. 2
Moisture Percent

Run
No.

Packing
Force

Apparent
Density

lbs .

1
2
3
4

36

1
2

54n

i
2

3
4

ii

ii
n

1 .4 2

ti
it

11

1.41
it
11

it

n

ii

Speed
m.p.h.

ii

79
n
it

11.75

1 .6 0
11
11

ti

.6 0

.93

1 .2 9

1.77
.6 0

.93
1.29
1.77
.6 0

.93
1.29
1.77

Draft
Requirement
lbs .

22.
23.
23.5
25.
22'.
24.
25.
28.
24.
25.
26.
29.

I l l

TABLE

XI

DRAFT REQUIREMENT OF A ONE-INCH TOOTH
Soil No. 2
Moisture Percent
Run
No.

Packing
F'orce

Apparent
Density

lbs.

1
2

3
k
1

2

3
k
1

2

3
k

36

tl

tl

It

It

It

1.51

tt

It

it

It

it

It

79
it

Speed
m.p .h.

It

5k

13.77

1.51
tt

it

it

it

it

Draft
Requirement
lbs .

.6 0

.93
1.29
1.17
.6 0

2 k.

27.
30.

.93
1.29
1.77

25.
28.
29.
31.

.6 0

28.

.93
1.29
1.77

29.
32.
35.

112

TABLE

XII

D R A F T REQUIREMENT OF A ONE-INCH TOOTH
Soil No. 3
Moisture Percent 7.25

Run

No.

i—
IC
\J r'Vd*

Packing
Force
lbs.

Apparent
Density

36
11

1.18

s

,

m.p.h.

11

.6 0

.93

t»

11

1 .2 9

II

ti

1.77

H O
J

II
II
11

H c\l rrW ‘

79it

1.19
ti
n
n
1 .2

n

11

11

11

11

.6 0

Draft
Requirement
lbs.

11.
' 11.5
11.5
11.

1 1 .

.93
1.29
1.77

n .5
ii.5

.6 0

1 1 .5

.93

n .5
n .5
12.

I .2 9
1.77

1 1 .

113

TABLE XIII
DRAFT REQUIREMENT OF A ONE-INCH TOOTH
Soil N o . 3
Moisture Percent
Run
No.

1
2
3
k

1
2
3

k

1
2
3

k

Packing
Force
IDs.

36
u
it
11

Apparent
Density

1.
18
11
ti
n

1.
19
11

9*83
„
,
p
m.p.h.

Draft
Requirement
lbs.

.60

14.5
15.
17.
18.

.60

isr
16. s

.93
1.29
1.77

it
11

n
11

.93
1.29
1.77

79
it

1.
2
tt

.60

n
11

11
11

.93
1.29
1.77

17.5
.

18

16.
17.
18.5
20.

114

TABLE XIV
DRAFT REQ UIREMENT OF A ONE-INCH TOOTH
Soil No. 3

Moisture Percent

Run

Packing

No.

Force

Apparent
Density

lbs.

1
2
3
4
1
2
3
4
1
2
3
4

36

11
u
11

if
ti
11

7911
it
11

1 .3 2
11
n
11

1.50
ti
11

it

1 .3 6
11
11
11

12.98

Speed

Draft
Requirement

m.p .h.

lbs .

.6 0

35.
36.
40 .
43.

.93

1 .2 9

1.77
.6 0

.93
1.29
1.77
.6 0

.93
1.29
1.77

33.
35.
40.
50.
42.
42.
35.

US

TABLE XV

DRAFT REQUIREMENT OF A :
FOUR-INCH PLOW
Soil No. 1
Moisture Percent 2.82
Run
No.

Packing
Force

Apparent
Density

l bs .
1
2

3
4
1
2

3
4
1

2

3
4

18
it
it
ii

36
ii

Speed
m.p.h.

1.3k
II
ii

It

1.37
n

.6 0

15.5
!(f.

1.77

17.5

.6 0

15.
15.
14.5
16.5

1 .2 9

.93

ii

1 .2 9

it

ii

1.77

it

1.38
ii

ii

ii

ii

n

lbs .

.93

it

5k

Draft
Requirement

i k '5

.6 0

15.

.93
1.29
1.77

14.5
15.5

116

TABLE

XVI

DRAFT REQUIREMENT OF A F OUR-INCII PLOW
Soil No. 1
Moisture

Run
No.

Packing
Force

Percent

App arent
Densi ty

lbs.

1
2
3
h

18

i
2
3
k

36

it

1.35
»
it

it

tt

1,37

ii

it

it

n

h

it

ti
it

Speed
m.p .h.

tt

1

2
3
k

3 .9 6

1.37
ti
ti
it

Draft
Requirement
lbs .

.60
.93
1.29
1.77

E .5
i5 .5
15.5

.60
.93
1.29
1.77

is.
is .5

.60
.93

1 .2 9

1.77

1 6 .5

16.
17.

12.5
U.
IS.

15.5

117

TABLE

XVII

DRAFT REQUIREMENT OF A FOUR-INCH PLOW
Soil N o . 2
Moisture Percent
Run
No.

1
2

3
4

Packing
Force
lbs .

Apparent
Density

36
n

1*39
11
ti

11

ti

i

3
4
1

1 J+1
11

2

3
4

11

11

it

n

79

11

n
n

Speed
m.p .h.

u

2

9*3-5

142
n
11

n

.60

Draft
Requirement
lbs .
18.

*93
1.29
1*77

19.5
19.5
19.5

.60

18.
18.5
22.
22.5

*93
1.29

1*77
.60

.93
1.29
1.77

19.
19.5
22.
22.

llfi

TABLE

XVIII

D R A F T R EQU IREMENT 0I(I A FOUR-INCH PLOW
Soil No. 2
Moisture Percent

Run
No.

1
2
3
k
1
2
3
k
1
2
3

b

Packing
Force
lbs.

Apparent
Density

36
it

1 J-|4
ii

it

ii

u

ii

h

79
it

Speed
m.p .h.

it

5it

10.1

1 J \2
ti
ti
ii

1 .i|2
ii

ii

ti

ti

ii

.6 0

.93
1.29
1.77
.6 0

.93
1.29
1.77

Draft
Requirement
lbs.

22.5
2ij.5
26.
29.5
23. 23.5
2k .
3°.

.6 0

25.

.93
1.29
1.77

27.
29.
30.5

119

TABLE

XIX

DRAFT REQUIREMENT OF A FOUR-INCH PLOW
Soil No. 2
Moisture Percent
Run
No.

Packing
Force

Apparent
Density

lbs .
1
2

3
4
1
2

3
4
1
2
3
h

36
ii
ii
it

1.57
it
it

ii

it

II

ii

II

79
it

Speed
m.p .h.

1.55
II

%

13.7

1 .4 6
II

it

II

it

II

.6 0

.93
1.29
1.77
.6 0

.93
1.29
1.77
.6 0

.93
1.29
1.77

Draft
Requirement
lbs .
35.
36.
37.5
40.
35.
33.
40.
42.
35.
37.
42.
45

120

TABLE

XX

DRAFT REQUIREMENT OF A FOUR-INCH PLOW
Soil No. 3
Moisture Percent

Run
No.

1
2
3
k
1
2

3
£
i
2

3
k

Packing
Force
lbs.

Apparent
Density

36

1.18

11

11
it

11

ii

1.19
ti

11
11

11

79
11

1 .2
11
11

ti

11

Speed
m.p .h.

n

%

7.88

tt

it

.6 0

.93
1.29
1.77
.6 0

.93
1 .2 9

1.77
.6 0

.93
1.29
1.77

Draft
Requirement
lbs.
19.
19.
19.5
19.5
19.5
20.
20.
20.
19.5
.
20.
20.

2 0

121

TABLE XXI
DRAFT REQUIREMENT OF A FOUR-INCH PLOW
Soil No. 3
Moisture Percent
Ru n

No.

Packing
Force

Apparent
Density

lbs .
1
2

3

b
l
2

3
4
1

2
3

b

1 .2

11
11

H
II

11
11

79i t
11
11

Speed
m.p .h.

36
n

-$k
it

9.7k

it

1 .2 1
11
11
it

1 .2 3
11
it

11

.6 0

Draft
Requirement
lbs .
19.

.93
1.29
1.77

21.
2 1 .5

.6 0
1 .2 9

22.
22.
2 b.-

1.77

25.

.6 0

23.
25.
30.

.93

.93
1.29
1.77

22.5

3 1 .

122

TABLE XXII
DRAFT REQ UIREMENT OF A FOUR-INCH PLOW
Soil No. 3
Moisture Percent

Run
No.

Packing
Force

Apparent
Dens ity

lbs .
1
2
3

4
i

2
3

b
i

2
3

4

»

36

11
11
11

5b11

1.35
11
11

n

l.^O
11
ti

11

11

ti

Speed
m.p .h.

ti

79
n

12,21

1-47
it

11
11

Draft
Requirement
lbs.

.6 0

30.

.93
1.29
1.77

bo.
45-

.6 0

.93
1.29
1.77
.6 0

.93
1.29
1.77

P'

33.
33.
37.5
45.
36.
36.

Jo.

43.

123

TABLE

XXIII

DRAFT REQUIREMENT OP' A

2.5 INCH TOOTH

Soil No. 2
Moisture Percent
Run
No.

Packing
Force

Apparent
Density

lbs.
1
2
3

4
1
2

36
u

1.27
ti

tt

it

it

1 .3 8
1
1

it

1
1

4

it

it

l

79
tt

3

2

3

4

Speed
m.p .h.

tt

54
tt

9*4-1

1.39
tt

.6 0

.93
1.29
1.77
.6 0

•93
1.29
.1.77

Draft
Requirement
lbs .
18 .5
20.5
22.5
23.
19.5
21.
21.5
24.

.6 0

20.

.93

21.5
23.
25.

it

it

1 .2 9

it

1
1

1.77

124

TABLE XXIV
DRAFT REQUIREMENT OF A 2.5 INCH TOOTH
Soil No. 2
Moisture Percent
Run
No.

1
2

3
4
l
2

3
4
l
2
3
4

Packing
Force
lbs .

Apparent
Density

36

147

tt

It

tt

tt

It

1.52
It

it

It

it

II

79t t

Speed
m.p.h.

ti

54
Tt

11.56

1 .5 1
it

it

it

it

ii

.6 0

.93
1.29
1.77
.6 0

.93
1.29
1.77
.6 0

.93
1.29
1.77

Draft
Requirement
lbs .
33.
33.
34«
38.
35 •
38.
t3940.
37.
38.
?9 *
42.

125

TABLE

XXV

DRAFT REQUIREMENT OF A 2.5' INCH TOOTH
Soil No. 2
Moisture Percent

Run
No.

Packing
Force

Apparent
Density

lbs .

Speed
m.p.h.

1
2
3
k

36
ti
it
i«

1.5
ii
n
i»

1
2

79

1.S4

3
k

13.3

.6 0

.93

1 .2 9

1.77

Draft
Requirement
lbs .

35.
38.
ko.
lj.2.5

,6 o
.93

36.5

ii

1 .2 9

ii

1.77

Uf.
50.

ii

it

ii

ti

126

TABLE

XXVI

DRAFT REQUIREMENT OF A 2.5 INCH TOOTH
Soil No. 3
Moisture Percent

Run
No.

Packing
Force
IDs.

H

36

OJ o'WJ-

II

Apparent
Density

1 11.1 9
11

II

11

i
H CM

1 .2 2
ii

II

n

It

ti

rH CM

7911

Sneed
m.p.h.

II

5it

10.32

1 .2 2
11

11

11

ti

11

Draft
Requirement
lbs.

.6 0

22

.93
1.29
1.7 7

25
27
31

.6 0

2k

.93
1.2 9
1 .7 7

23
2^
33

.6 0

28
30
32

.93
1.2 9
1.7 7

35

12?

TABLE

XXVII

DRAFT REQUIREMENT OP' A 2.5 INCH TOOTH
Soil No. 3
Moisture Percent
Run
No.

Packing
Force

Apparent
Dens ity

lbs.
1
2

36
ti

■?
b
1
2

3
b

Speed
m.p .h.

1.37
11

.6 0

.93

11

tt

1 .2 9

11

11

1.77

1.38

%
11

ti
ti

11

11

1
2

7911

3

11

i

12.79

it

1 .43
11

ti
ti

.6 0

.93
I .2 9
1.77
.6 0

.93
1.29
1.77

Draft
Requirement

lbs.
35.
37.
38.
5o.
33.
35.
37.
k2 .
37.
38.
£l.
Ii8.

128

TABLE XXVIII
DRAFT REQUIREMENT OF A SEVEN-INCH DISK
Soil No. 3
Moisture Percent

Run
No.

Packing
Force

Apparent
Density

lbs.
1
2

36
1!

1 .2 6
11

11

11

II

11

1
2

Sb11

1
2

3

1 .2 1
11

ti

ii

11

it

79
11

Speed
m.p.h.

?
k

3
k

8 .8 3

1.28
11

11

ti

11

ti

.6 0

.93
1.29
1.77
.6 0

.93
1.29
1.77
.6 0

.93
1.29
1.77

Draft
Requirement
lbs.
8
8
8
8
8
8
8
8
8
8

9

10

129

TABLE XXIX
DRAFT REQUIREMENT

OF A SEVEN-INCH DISK

Soil No. 3
Moisture Percent

Run
Ho.

1
2
7

Packing
Force
lbs.
36

I*
11

z

ti

1
2
3

5k1?

1
2
3

79

k

i

11
11

11
11
11

Apparent
Density

10.29

Sneed
m.p.h.

1 .2 6
11

ti
it

1 .3 0

ti
n
ti

11
.3
11

ti
11

.6 0

.93
1.29
1.77
.6 0

.93
1.29
1.77
.6 0

.93

1 .2 9

1.77

Draft
Requirement
lbs.
10.
11.
1 3 .5
15.

ik.
16.
19.
22.
17.
22.5
28.
32.

TABLE XXX
DRAFT REQUIREMENT OF A SEVEN-INCH DISK
Soil No. 3

Moisture Percent
Run
No.

Packing
Force
lbs .

Apparent
Density

1

3b

2

ii

1.41
ti

n>
-

11

4

ii

ti

1

54it

1 .48
ti

3

ii

11

ti

it

i

79
it
it
it

k

2

3

k

Speed
m.p ,h.

it

2

12.71

l.ii.9
II

II
II

.6 0

.93
1.29
1.77
.6 0

.93
1.29
1.77
.6 0

.93
1.29
1.77

Draft
Requirement
lbs .
23.
24.
25.
27.
25.
27.
29.
32.
30.
35 .
37.
40.

131

TABLE XXXI
THE FRICTION DETERMINATION OP’ THE TOOL CARRIER IN THE SOIL BOX
Speed
m •p til<
.6 0

.94
1 .2 9

1.77
.6 0

.9^
1 .2 9

1.77

Load, on the
Tool Carrier
lbs.
10
10
10
10

12
12
12
12

20
20
20
20

22
22
22
22

.6 0

30

.94

30
30
30

1 .2 9

1.77
.6 0

.94
1 .2 9
1.77

.6°
•94
1 .29
1 .7 7

Dynamometer
Reading
lbs.

32
32
32
32

39
39
39
39

b}

ft

ft

ft
ft

ft
ft

5?

ft

{A
n-1

TOOL

MO D’iN/MOrtZTe'R
IN 30IL 60%

C **nȣK

132

m

Pig.

kZ

133

K
h
%

<Q

*
*
-j *
*
M
O

*
v»

5

O

VS
•o

tc
VK
** Q

^1
o
n

l

*
I4 CJ
> m
Z
VI
»*
s

1

♦
M

Pig. 43

3

W

I

m

OCV-

?e
Ir*
a
®
Q®
Is

£
4«.*
-*5fc
“*
£
C
*" >o
*£

J tL f

ALIMHC

BFONZt JOURNAL

B C A R IM -tf

[J2

«j O \>

Fig. %

135

9 k

..uiL

•**
*
s s
* *
§ tg'
k u
•JO *
s.
«0 >>
• VI
Q *
*% Hi u.
ttl
•J \5 •»
m
*
V) V) 2
*> *

Fig. IfS

Kaor TMFT£R

136

Pig. 46

REFERENCES
1.

Ashley, Wallace. A method of comparing plow bottom shapes.
Ag. Eng. J., Vol. 26:35, Jan. 1932.

2.

Bacon,
C. A. Plow bottom design. A g . Eng. Transaction.
Vol. 12:26, 1918.

3.

BaVer,
L. D. The physical properties of soil of interest
to agricultural engineers. Ag. Eng. J., Vol. 13:324,
Dec. 1932.

4.

Baver,
L. D. The Atterberg consistency constants:
Factors
affecting their values and a new concept of their signi­
ficance.
J. Am. S o c . Agron., 22:935-948, 193°.

5.

Baver, L. D. Soil PhysicSj*
John Wiley and bons, Inc.,
New York.
Second edition, 1948.

6.

Bouyoucos, G. J. A simple and rapid method for measuring
the stickiness of soil. Soil Sc. 34, No • 5:393“4lO, 1932.

7.

Bouyoucos, G. J. Recalibration of the hydrometer method
for making mechanical analysis of soils. Agronomy Journal,
Vol. 43:434”8, September 1951.

8. Brown, Theo. Engineering development of tillage equipment.
Ag. Eng. J. Vol. 12:211, June 19319.
10.
11.

Brown, Theo. Some fundamentals of plow design.
Transaction, -Vol. 19:24, 1925-

Ag. Eng.

Browning, G. M. Principles of soil physics in relation to
tillage. Ag. Eng. J., Vol. 31:341, 1950•
Browning, 0. A.
Present status of the plow as a tillage
implement. Ag. Eng. J., Vol. 25:7, 1944*

12.

Clyde, A. W. Mechanics of plow and tractor hitches.
Eng. Transaction, Vol.. 28:28, 1934*

Ag.

13.

Clyde, A. W. Measurement of forces on soil
Ag. Eng. J., Vol. 17:5, Jan. 1938.

tillage tools.

lij..

Clyde, A. W. Load studies on tillage tools.
Vol. 18:117, 1937*

Ag. Eng. J.,

138

15.

Oljcle.^A.^

The problem of soil tilth.

16.

Clyde, A. W . Improvement of disk tools.
Vol. 20:215, 1939.

Ag. Eng. J.,
Ae. En«. J
’

17.

Clyde, A. Vj . Mounted plows and their effects on the
tractor. Ag. Eng. J., Vol. 2:167, 1940.

18.

Collins, E. V. Factors influencing the draft of olows.
Ag. Eng. Transaction. Vol. 14:39, 1920.

19.

Collins, E. V. Making a tractor dravfbar test.
J., Vol. 2:19, Jan. 1921.

20.

Collins, E. V. The direct application of mechanical power
to soil tillage. A g . Eng. J*., Vol. 10:165, May 1 9 2 9 .

21.

Cook, R. L. A comparison of tillage implements. Ag. Eng.
J., Vol. 31:211, 1950.

22.

Davidson, J. B.
Influence of speed on the draft of plows.
Ag. Eng. Transaction, Vol. 13:69, 1939•

23.

Davidson, J. B. The manless plow.
Vol. 18:53, 192if.

24.

Davis, Dale S, Empirical E quation and Nhmqgraphy. McGrawHill Book Company, Inc., New York and London, 1943*

25-

Dejuhasz, K. J. and Clyde, A. W. Model experiments on
tillage tools. Pa. Exp. Sta. Instruments, 12, 1939,
N.S.P. 144, Penn. Sta. Bui. 3^2, p. 19.

26.

Dover, Ralph D.
and Nichols, M. L. Dynamics of soil on
plow moldboard surfaces related to scouring. Ag. Eng.
Transaction, Vol. 28:9, 1934*

27.

Duely, F. L. and Jones, M. M. Effect of soil treatment on
the drai't of plows. Soil Science, 21, No. 4 ;277-238, 1 9 2 6 .

Ag. Eng.

Ag. Eng. Transaction,

28.. Fletcher, L. J.
The development of deep tillage in Cali­
fornia. Ag. Eng. Transaction, Vol. 17:202, 1923.
29.

Gray R. B. A farm tillage machinery laboratory.
J . / V o l . 15:6, 1934-

30.

Green, John M. Some rotary tillage applications. Ag. Eng.
J., Vol. 27:175, 1946.

31.

Gordon, E. L.
Physical reactions of soil on plow disks.
Ag. Eng. J., Vol. 22:205, 194^*

Ag. Eng.

139

32.

Haines, Vy. 3. Stuaies in the physical prooerties of so '1 s
and mechanics 1 properties concerned in cultivation.
J. Apr. 3ci. (England)' 15, No. 2:178-200, 1925.

33*

Haines, W. B. Studies in the physical propeities of soils.
J. Apr. Sci. (England) 15, No. 4 :529-543, 1925.

34.

Haines, R. G. Analysis and control of landsides.
ton Engin. Exp. St. Bui. 91:57, 1 9 3 6 .

35-

Iyer, P. V. K. and Kao, P. S. Preliminary ,investigation
into the influence of the fundamental dimensions of a plow
and drawbar pull depth and resistance per unit area.
J.
A g r . Sci. lli.:2[|.0-lj, June, 1944*

36.

Jennings, B. A. Plow adjustment,
381:1-36, 1942.

37*

Keen, E. A.
The use of the dynamometer in soil cultivation
studies and implement trial.
J. of Royal Agr. Society of
England 36:30-43, 1925*

Washing­

Cornell A g . Ext. Bui.

3 8 .' Keen, B, A. and Haines, W. B.

I-IIJ.

Studies in soil cultivation
J. of Agr. Sci. (England) 15, N o . .3:375-4-06, 1925.

39»

Keen, B. A. Physical research on problems of soil culti­
vation.
Tropical Agr. 19:143, July, 1942.

1;0,

Keen, B, A. The Physical Properties of The Soil.
Longmans, Green and Co., New York, 1931.

41.

hummer, F. A. and Nichols, M. L.

The dynamic prooerties

of soil.
IV - a m eth o d of analysis of plow moldboard
d e s i g n based u p o n dynamic pr o p e r t y of soil.
Ag. Eng.

J. Vol. 13:279, Nov. 1932.
42.

Kummer, F, A'. and Nichols, M. L. A study of nature of
physical forces governing the adhesion between soil and
metal surfaces. Ag. Eng. J., Vol. 19:73, 1938.

43.

Kummer, F. A. The dynamic properties of soil. VIII The effect of certain experimental plow shapes and materials
on scouring in heavy clay soils. Ag. Eng. J., Vol. 20:111,
1939.

44.

King, F. H .
Physics of Agriculture.
Wisconsin, 189^.

45.

Kurnmer, F. A. Dynamic properties of soils as applied to
the elements of implement design (Experiment on wooden
and metal plow). Alabama Sta. Report, 1938, pp. 1-8.

F. H. King, Madison,

1A0

46*

Kummer, F. A. The dynamic properties of soils,
J., Vol. 26:21, 1 9 45.

A g . Eng.
b

47*

Langh&ar, Henry L. Dimensional Analysis and Theory of
Models.
John Wiley and Sons, Inc., New York, 1951.

48 •

Lindgren, A. C. Coordination of theory and practice in
plow design and operation. A g . Eng. J., Vol. 15:150, 1920.

i|9•

Lucas, D. B. Plowing draft tests on fertilizer plots.
Ag. Eng. J., Vol. 9:335, Nov. 1 9 2 8 .

50.

KcKibben, E. G. The soil dynamic problem.
V o l . 7:9-12, D e c . 1926 .

51.

McKibben, E. G. A study of the dynamics of the
harrow. Ag. Eng. J., Vol. 7:92, March 1 9 2 6 .

52.

Nichols, M. L. An analysis of soil dynamics:
Factors
affecting the operation of tillage and tractor machinery.
Ag. Eng. Transaction, Vol. 17:174, 1923.

,

Ag. Eng. J.,
disk

53*

Nichols, M. L. Methods of research in
applied to implement design. Alabama
1929.

soil dynamics as
Sta. .Bui. 229-27,

54.

Nichols, M. L.
The dynamic properties of soil.
J., Vol. 12:321, August, 1931.

55.

Nichols, M. L. Methods of research in soil dynamics as
applied to implement design. Ag. Eng,
J., 13:279-285,
1932.

56.

Nichole, M. L. The dynamic properties of soil; shear
values of uncemented soils. A g . Eng. J., Vol. 13:201,
Aug. 1932.

57.

Nichols, M. L. The dynamic properties of soils by means of
colloidal films. A g . Eng. Transaction, Vol. 26:37, 1932.

58.

Nichols, M. L. and Reed, I. F. Physical reactions of soils
to plow moldboard surfaces. Ag. Eng. Transaction, Vol. 28:
14, 1934.

59.

Nichols, M. L. and Doner, R. D.
(V) Dynamics of soil
on plow moldboard surfaces related to scouring. Ag. Eng.
J . , V o l. 1 5 :9 , 1934-

60.

Randolph, John W. A method of studying soil stresses.
A g . E n g . J . , V o l . 6 : 1 3 4 , June 1 9 2 5 .

Ag. Eng.

141

61 .

Randolph, John W. Tests of tillage tools.
Vol. 19:29, 1938.

62.

Rood, I. I*. The status of research on plowing problems.
Ag. Eng. J., Vol. 15:3, Jan. 1934.

6 3 * Reed, I. P .

Tests of tillage tools.
and procedure for moldboard plows.
1 8 :111, 1937.

Ag. Eng. J.

I - Equipment
Ag. Eng. J.. Vol.

61[. Reed, 1 . 1 . Tests of tillage tools.
Ill - Effect of
shape on the draft of fourteen inch moldboard plow
bottom. Ag. Eng. J., Vol. 22:101, 1941.
65.

Reed, I. E. Some factors affecting design of tillage
machinery and proposed approach to their evaluation.
Soil Sci. S o c . Amer. Proc. 9:223-5, 45, 1944*

66.

Richards, L. A. Pressure membrane apparatus - construction
and use. A g . Eng. J. 10:451-54, Oct. 1947.

67.

Richards, L. A. Methods of measuring soil moisture tension.
Soil Sci. Vol. 68, No. 1:95-112, July, 1949.

68.

Russel, J. C. Report of committee on soil consistency.
Amer. Soil Survey Assoc. ftul. 9:10-22, 1928.

69.

Seaholm, J. P. Problems of plow bottom manufacture.
Ag. Eng. J., Vol. 15:7, 1934-

70.

Sjogren, 0. W. Development of offset disk harrow. A g .
Eng. J., Vol. 17:503, 1936.

71.

Slipher, John A. The mechanical manipulation of soil as
it affects structure. Ag. Eng. J. 13:7-10, 1932.

72.

Stirniman, E. J. Draft test of farm machinery.
Transaction, Vol. 11:9, 1917.

73.

Trullinger, R. W. The fundamental approach to tillage and
traction research problems. A g . Eng. J., Vol. 18:17, 1937.

74.

Walker, H. B. The engineer and tillage research.
J., Vol. 11:281, Aug. 1930.

75.

Williams, Ira. L. Measurement of soil hardness.
Eng. J., Vol. 20:25,
1939.

76.

Yoder, R. B., et_ a1.
physical property of
pp. 7-9«

Ag. Eng.

Ag. Eng.
Ag.

Report on the investigation of
soil. Alabama Station R p t . 1937,

tflC H lC A N
PC,
D /t T £

!Z -3 a -5 3

P E .5 I G N S O i j r

s ,T

STATE
EHa .

CALL E P E

DEPT
■ J c /fte
D R AW /V t>y

AiJEM BLy
D RAWI NG
S O IL
T R O U G H FOR T IL L A G E

EXPERIMENTS

i* * tm
3 .T .