THE EFFECTS OF COMPACTIONOF DIFFERENT GOLF GREEN SOIL MIXTURES

ON PLANT GROWTH

Raymond John Kunze

THE O.I. NOER MEMORIALTURFGRASS COLLECTION

| MICHIGAN STATE UNIVERSITY LIBRARIES

TEE EFFECTS OF COMPACTION OF DIFFERENT GOLF OlEEN

SOIL MIXTURES OH PLOT? GROWTH

A Thesis

by

Raymond John Kunze

Submitted to the Graduate School of theAgricultural and Mechanical College of Texas in

partial fulfillment of the requirements for the degree of

MASTER OF SCIENCE

August, 1956

Major Subject: Agronomy

THE EFFECTS OF COMPACTION OF DIFFERENT GOIi1 GREEN

SOIL MIXTURES ON PLANT (SiCXITE

A Thesis

Raymond John Kunze

Approved as to Style and Content "by:

(Cbairman of Committee)

(Head of Department or Student Advisor)

August, 1956

ACKNOWLEDGEMENT

The author is especially indebted to Dr» J. Bo Page, the

committee chairman, and Dr. Marvin Ferguson, U. S. Go A, South-

western Director, for their guidance, time, and consideration given

on various phases of the thesis problem* Gratitude is also ex-

pressed to Mr. C. B. Godbey, Head of the Genetics Department, Dr.

E. B. Middleton, Dr. H. H, Had ley, and Dr« H. R* Blank for their

suggestions and criticisms.

Special thanks is also due the United States Golf Asso-

ciation for providing the monetary grant that made this study possi-

ble.

•TABLE OF CONTENTS

I. INTRODUCTION 1

II. REVIEW OF LITERATURE .•. 3A* Direct Effects of Compaction..-. .. 3B. Indirect Effects of Compact ion..... „... • k-

1. Aeration. • • h2 • Permeability •........••. 5

C. Interaction Effects.............o . 6

III. METHOD <,..•.<>. 8A. Field Procedure...•„<,„.o ............ 8

1. Construction of the experimental green... 82. General maintenance practices 133. Compaction treatments 1*4-k• Clipping procedure.„...«.........•••• 175. Procedure for taking the undisturbed soil cores.. 186. Sampling procedure for the soil aggregate analy-

ses • ••••••••••. ••<>. ••.••>••«. o.. a . . . o 207. Removal of the roots from the soil mixtures 20

B. Laboratory Procedure...<,... •....• • 211. Permea'bility measurements.....••.•»••• 222. Porosity measurements.•••••••••••.•• •••••••• 243. Soil aggregate analyses 2k

IV. RESULTS.... 25A. Clipping Yield Data........ .<,.... 25B. Root Weight Data 30C• Porosity Data ••«••••••....... •••••••••• 36D • Soil Aggregate Analysis Data 38E. Bulk Density Data .. • o , k6F. Permeability Data...... ......;........ k-6

V. DISCUSSION <.... ».. kQA. Variation in Root and Top Growth between Various

Mixtures h8B. Effects of the Modified Physical Soil Properties on

Root and Top Growth 50

VI. SUMMARY A M ) CONCLUSIONS „ 53

VII. REFERENCES 56

VIII. APPENDIX o.....» 60

FIGURES

1« Several sketches showing various aspects of the fieldoooooooooooaoooooooooo0ooooo»oooo«oo«e»«•••••••• 10

2* A sketch of the compacting device and the container

3« A cutaway diagram of the apparatus used for taking theundisturbed soil core samples© »o»©o<>©ooo•»•«•«•««•••••••*»• 19

k. A cutaway diagram of the permeameter unit used formeasuring the infiltration rates through the undisturbedsoil core S8&p.i£s«o«»«o»o»oto««««o»««««««o»««»**6»««it*»i*** *-j

5* Average clipping yields of top growth, removed prior tocompaction treatments, from mixtures of different parti-C l e S lZeS o a o o «•» o o o o o o o • o e a o * o o o o « e o e o o o o e o o o o »• o • • » • • • • • • • <—D

$• Average clipping yields of top growth, removed prior tocompaction treatments, from mixtures of different sand-clay soil—peats ratios•»»»««t«*«t«ooa«»»o»««»*»««»«»«»»»it*t <-̂

7« An average of 2 clipping yields of top growth, removedafter the compaction and during the high moisture treat-*merits, from mixtures of different particle sizes*•• •«•••••• 28

8« An average of 2 clipping yields of top growth, removedafter the compaction and,during the high moisture treat-ments, from mixtures of different sand-clay soil-peatratios•«••«© ©««»o«(*ttti«»»«»o«««t**»t»t«i«»i«i»«*t«»iti«»* •—o

9« Differential effects of the different sand-clay soil-peatratios of 5 particle size mixtures on yields of 2 clip-pings following the compaction treatments««©••••••*••••••••> 29

10. Differential effects of the different sand-clay soil-peatratios of 5 particle size mixtures on yields of 2 clip-pings following the compaction and during the high mois-ture treatlBeKltS 30fte«90t>««t«g«9«ooe«»e«t«««i«»i«*(i«tii»<« t-y

11* The effect of various sand-clay soil-peat ratios of thecompacted and non-compacted mixed particle size mixtureson yields of 2 elippiagsi#aken during the high mol&ture

a

The effects of mixtures of different particle sizes on

13* Typical examples of roots found in mixtures of variousparticle sizes©•©o>««»«o«•»»«««««««««o»«»»««««»««^«<•»•••••

1^, The effects of the sand-clay soil-peat ratios of the com-pacted and the non-compacted mixed particle size mixtureson total root weight«.« .................. 35

15 • The relationship between the total, clipping yield of the1-0*5 mm, and mixed particle size mixtures and the non-caplllary porosity.....•• ..... .................. 37

16• The effects of the compacted mixtures of different par-ticle sizes on the non-capillary pore space....••..•••••.•• 39

17. The effects of the compacted mixtures of different sand-clay soil-peat ratios on the non-capillary pore space 39

18. The effects of the compaction treatments on the capillaryand non-capillary porosities of the mixed particle sizemixtures «o.... kO

19. A comparison of the percent of aggregation in preparedmixtures "before and after these mixtures had undergonefield treatments • k2

20. A comparison of the aggregate size distribution "betweenthe compacted and the non-compacted 0-9-1 mixtures......... kk

21. A comparison of the average aggregate size distributionamong the 6-3-1, 7-2-1, 8-1-1, and 8J-J-1 compacted andnon-compacted mixtures«•••<>•.»•••»•«•••.••••••••••••••••••• hh

TABLES

1* The particle size distribution of commercial concretesand as determined "by a sieve analysis***....•..••.......••.• 11

Z% Mixtures of various particle sizes and of various sand-clay soil-peat ratios tested in the experiment •*»••••••••».»• U

3* The amount of compactive energy received "by the compactedmixtures and the date applied*«««»»o«*»o««•««•<»<»«»«.«*««.*•*• 17

k9 Grams of the oven-dried plant materials removed from theturf grown on individual soil mixtures in the first clipping.Clipping date: June 9? 1955»«o<>•••• <»<>••»•<»<>«>•••••••••••••••• 61

5. Grams of the oven-dried plant inaterials removed from theturf grown on individual soil mixtures in the second clipping*Clipping date: July 21, 1955«o.«><»o«»«».•*•..••••*.••..••••••• 62

6. Grams of the oven-dried plant materials removed from theturf grown on individual soil mixtures in the third clipping*Clipping date: Hovember 22, 1955«»0.«><»<»oo..o.o..••....••...• 63

7« Grams of the oven-dried plant materials removed from theturf grown on individual soil mixtures in the fourth clippingClipping date: April 20, 1956o<,d»...*.0...*.....»........•.• 6k

8# Grams of the oven-dried plant materials removed from theturf grown on individual soil mixtures in the fifth clipping.Clipping date: May 10, 1956,eo***o.»....»»»•••......•»*••••* 65

9* Grams of the oven-dried plant materials removed from theturf grown on individual soil mixtures in the sixth clipping.Clipping date: June 2, 19^6»»ooo«»»«o»..o*«o»««.••••.»..#*.. 66

10. Grams of the oven-dried roots removed from the undisturbedsoil core samples taken from the individual soil mixtures.... 67

11. Grams of %fee total oven-dried roots removed from the indi-S O x J . U1XX t / U r e S o o « o . o o o o e o a o o « e o e . « o . o . • • • • * . . . . . . . . . . . . 0 0

12. Percent non-capillary pore space in the undisturbed soilcore samples taken from the individual soil mixtures,•••••... 69

13* Percent capillary pore space in the undisturbed soil coresamples taken from the individual soil mixtures••..o.••••»•«. 70

1̂ -. Percent total pore space in the undisturbed soil <jore sam-ples taken from the individual soil mixtures.<>««»•«•••••••»•• 71

15• Bulk density measurements (in grams per cubic centimeter)of the undisturbed soil core samples taken from the indi-

S O i l m i X t U r e S o o o e e o o o < * o e e c o o e c c i 0 o « o o * * a e o « o o « * o » * * * « « « I 2

16. Permeability measurements (in inches per hour) of theundisturbed soil core samples taken from the individual

17• Percent of aggregate sizes in various ratios of themixed particle size soil mixtures* •••<>o <,•«>•»•<,•• •«•««•••••••• 71*-

18. Percent of aggregate sizes in various partiele sizeQ*"3"*1 soil mixturest«oo»«oooo«i)»««o«oi«•»»«• ••»•••••••••••••• fp

INTRODUCTION

The increased popularity of golf has made more difficult

the "basic soil physical problems encountered in maintaining a suit-

able vegetative cover and putting surface on a golf green. Gener-

ally, superintendents are aware that the "root of the problem" lies

in the medium in which the grass plants are growing. Many differ-

ent types of golf green soil mixes have been prepared on an empiri-

cal basis. Some of these mixes have produced good greens through

the succeeding years while others have failed completely. Some of

these failures can be attributed to poor management while the fail-

ures of others appear to be caused by several different factors.

One of the difficulties encountered in building a golf

green is the choice of the proper sand-clay ratio for the soil mix-

ture. The problem becomes more complex when as frequently happens

particle size analyses of existing greens show almost complete

similarity in particle sizes between soil mixes of a good and a poor

green. Obviously, if the mechanical analyses show no differences

in the amounts of sand, silt, and clay in the different mixtures,

then one of the components must have different inherent physical or

chemical characteristics than the same component in the other mix-

ture, Together with the chemical properties, the importance of the

physical characteristics of the soil mixture, such as capillary and

non-capillary porosity, permeability, degree of aggregation, and

bulk density cannot be over-emphasized.

Nature has endowed very few soils with the chemical and

physical properties that meet the specifications of a good golf green

soil mixture* Although man has found reasonable means of controlling

and maintaining the fertility of a soil, he has had very little success

in the alteration of its physical properties. Soils that possess

highly desirable physical and chemical assets are often used as the

sole component of a golf green soil mixture. These may do quite veil

for a number of years, depending upon the stability of the soil aggre-

gates. Keeping a normal soil aggregated under field conditions in most

areas is itself a problem* Soils used on golf greens are subjected to

dally applications of water, to compaction "by players and maintenance

machines, and to a high nutrient level that accelerates the decomposi-

tion of organic materials• Under these conditions there is an over-

•whelming amount of circumstantial evidence and also considerable experi-

mental evidence that the physical properties will not "be maintained at

a level that will produce turf with a desirable playing surface.

One way to overcome this undesirable change in soil structure

is to create a soil mixture that will withstand compaction and high

moisture treatments and still possess the maximum of the chemical char-

acteristics that are so necessary for good plant growth. Hence the

objective in this investigation was to find a superior sand-clay soil-

peat mixture and to measure its performance "by clipping yield and total

root weight of grass grown under regular golf green conditions.

REVIEW OF LITERATURE

The effect of compaction on the physical properties of soil

and on p3.ant growth has received considerable attention within the last

decade. This increased emphasis on compaction studies indicates the

seriousness of the problem. Because compaction has both direct and

indirect effects on plant growth, the problem becomes very complex and

the significance of the individual factors involved is very difficult

to determine*

Direct Effects of Compaction

The main factor affecting growth of plants under compaction

is the mechanical impedance of plant roots. Taubenhaus, Ezekial, and

Rea (kl) found that compacted soils prevented or seriously affected

root penetration and also caused a constriction of cotton roots* This

root strangulation seemed to occur only in flat, poorly drained, heavy

clay soils which were compacted by continuous rain or irrigation and

then further hardened in absence of cultivation by hot dry weather •

Other roots were found with needle like and bead like calluses which were

formed in the area of the compact layers.

Veihmeyer and Hendrickson (hh) in a study of root growth of

sunflowers in several different soils found that roots penetrated a

gravelly loam soil to a depth at which the bulk density was 1.80 and in

an Aiken clay soil to a depth at which the bulk density was 1*2*6 • They

stated that the amount of porosity was not a limiting factor, but rather

the size of the pores in permitting entry of roots *

This theory is somewhat corroborated by the work of Doneen and

Henderson (10)• These investigators grew wJieat and several other com-

mon plants in a compact Yolo clay soil. It was found that none of the

plants except wheat had any appreciable number of roots in the compact

soil. This was attributed to the fact that the wheat roots had a

smaller diameter than any of the other plant roots studied*

Lawton (23) in a study of corn and Smith and Cook (ho) in a

study of sugar beets found that compaction of the soil gave greater re-

ductions of growth than high soil moisture treatments. In each case

forced aeration somewhat alleviated the effects of compaction. Hubbell

and Gardner (20) observed that compaction at 35 pounds per square inch

produced a greater lowering of aggregation than did water logging and

sealed soil samples. On the contrary Watson (̂ 5) and Harper (18)

found that high moisture levels exerted a greater influence on turf

quality than did soil compaction*

Indirect Effects of Compaction

Aeration:

An aggregated clay soil tends to have large pores, but after a

severe compaction, aggregates are destroyed and the size of the pores

reduced. In turn aeration is reduced, and this impairs root respiration.

Consequently absorption of water and nutrients is reduced, followed by

a resulting reduction in plant growth.

Bertrand and Kohnke (3) in experimenting with corn found that

diffusion of oxygen was much slower in compact than in loose subsoil. A

high moisture content intensified the restricting effects of a dense sub-

soil on oxygen diffusion and root growth.

Baver and Farnsworth (2) reported losses of sugar "beets of

nearly 50 percent on soils in which non-eapillary porosity was less

than 2 percent. They further suggested that aeration of the soil is

likely to become a limiting factor in plant growth if the air capacity

is "below 9 percent • In growing "barley in culture solutions Bryant (7)

found real anatomical and histological differences in barley roots

grown in aerated and non-aerated solutions. Taylor (̂ 2) has shown

quite conclusively that oxygen diffusion is strongly affected by the

degree of compaction and by the moisture content of the soil.

Page and Bodman (33) give an excellent review on the mechanics

of soil aeration and! the effects of aeration on root growth and nutrient

uptake. Peterson (3*0 and Russell (39) also give good reviews of the

relationships between soil air and plant roots.

Permeability:

Permeability is largely controlled by the same physical char-

acteristics that affect aeration. Size, density of packing, and hydra-

tion of particles are probably the most important factors. Doneen and

Henderson (10) found that a saturated soil above a compacted layer

caused an anaerobic condition resulting in the rotting of the root sys-

tem and decreased depth of the plant root. In cases where roots did

penetrate a dense layer, it was found that the roots were slender and

few in number. If a more friable soil was present below, there was

evidence of considerably more branching of roots.

Garman (15) studied the permeability of the various components

of a golf green soil mixture under compaction. His work showed that

peat when compacted a,t field capacity became almost impervious to water.

6

Compacted sand-clay soil mixtures with approximately 8 percent clay "by

weight were found to retain adequate infiltration rates. The work of

Lunt and Wyekoff (27) indicated that when the proportion of sand is a-

"boisrl; 85 percent "by volume in a mixture infiltration rates remain high

in spite of compaction*

Interaction Effects

Evea with rather large amounts of experimental work conducted

on soil compaction as it affects soil physical properties and the re-

sulting root and top growth of plants, it is difficult and in most in-

stances impossible to separate direct from indirect effects* According

to Gill (17) in his study of aeration and mechanical impedance of seed-

ling roots there are only a few physical properties of the soil which

influence the "behavior of plant roots* However, tljeir interactions are

so complex as to make it almost impossible to reach quantitative conclu-

sions with respect to the significance of the individual factors. Gill

developed an apparatus whereby he could simultaneously study the effects

of mechanical impedance and oxygen supply to the root. He found evi-

dence of growth at concentrations of oxygen as low as 1 percent in the

absence of mechanical impedance* On the other hand the rate of growth

fell to zero at relatively small levels of impedance with the same level

of oxygen. The ability of the root to enlarge in the presence of a con-

stant mechanical restraint was greatly impaired "by relatively modest re-

ductions in oxygen content.

Since the productive capabilities of a soil mixture appear to

be largely controlled by its ability to resist compaction, the chief

emphasis in this investigation was placed on making a fundamental study

of haw maintenance of favorable soil properties would "be assured.

8

METHOD

Field Procedure

To evaluate properly the effects of the physical properties

of each individual mixture upon the over-all productiveness of the mix-

ture, it was necessary to set up a controlled field experiment "whereby

a comparison could be made "between the performance of different mixtures*

An evaluation of these mixtures was made "by analyzing clipping yield

weights and total root weights. Physical measurements were made of each

mixture at the conclusion of the experiment. An attempt was made to re-

late the magnitude of these measurements to the clipping and root yields

produced•

Construction of the experimental green:

A site for the construction of an experimental green was ob-

tained on the Texas A, and M. College golf course which is in a north-

easterly direction adjacent to the college campus. An area of 12 by 30

feet was leveled by a cut and fill method. A subsurface drainage system

with a 2 percent slope was installed by digging three equally spaced

trenches lj feet wide, 1 to 1-J- feet deep, and 30 feet long. These were

Joined together at the lower end by a similar trench that emptied into

a nearby open drainage ditch. The trenches were filled with a uniform

size gravel to within 10 inches of the surface of the soil. To reduce

the possibility of fine soil particles migrating into the gravel zone an

inch of concrete sand was placed on top of the gravel layer.

Oil containers of 5 luart capacity with the tops removed were

placed on top of the sand layer. The natural soil of the area was then

returned to fill the remainder of the trench. Subsurface drainage

from the container to the porous layer below was facilitated "by three

•|-inch holes in the •bottom of each container* Figure 1 shows a dia-

gram of the general layout and the drainage system for the experimental

green.

Commercial concrete sand was used as the skeletal agent for

the soil mixture. It was used in a natural mixed form and in five

sieved sizes. Due to the differences of the amounts between different

sieved sizes as shown in Table 1, replications of mixtures of some of

the uniform particle sizes were omitted,

Houston Black clay soil which has predominantly a montmoril-

lonite type of clay mineral was obtained from the experiment station

at Temple, Texas. The top 6 inches of soil was taken from a meadow

that had never been in cultivation. The soil was placed in a green-

house and subjected to repeated wetting and drying cycles until the

size of aggregates was reduced to 5 millimeters or less. A mechanical

analysis by the pipette and sieve methods indicated that the sample

was 57 percent clay, 3^ percent silt, and 9 percent sand. A soil ag-

gregate analysis by the Yoder (kj) wet sieve method showed 91 percent

aggregation (uncorrected for primary particles). Additional informa-

tion on the chemical, physical, and mineralogical characteristics of

this soil have been presented by Kunze and Templin (22).

After the soil was broken down by repeated wetting and dry-

ing cycles into aggregates of 5 millimeters or less it received a soil

conditioner (Monsanto*s polymer 212-100 D powder) treatment equivalent

to 2,000 pounds per acre. It was applied in a liquid form in two

10

Ground Embedded5 Quart Containers

General Layout of Plot

5 Quart Container

Fill

Mixed Con-crete Sana

Fine UniformSize Gravel

Vertical View of EmbeddedContainer and UnderlyingDrainage Materials

Bottom ofContainer

in

View Shoving 3i -Inch Holes inthe Bottom ofContainer

Figure 1« Several sketches showing variou- aspects of tl;e field plotlayout.

11

Ta"ble 1. The particle size distribution of commercial concrete sandas determined "by a sieve analysis.

Size

5-2 mm.#2—1 mm*1-0,5 KKU0.5-0,25 mm,Less than 0.25 mm.

Percent

1913273k7

# Millimeter

Ta"ble 2. Mixtures of various particle sizes and of various sand-claysoil-peat ratios tested in the experiment.

Mixtures of Sand and Clay Particle Sizes

Ratios*

Batios

5-2 mm.

6-3-17-2-18-1-1

6-3-17-2-18-1-1

8^-^-1

1—0.5 mm.

6-3-17-2-18-1-1

O.5-O.25 mm.**

6-3-17-2-18-1-1

<D.25 mm.

6-3-17-2-18-1-1

Mixed***

0-9-16-3-17-2-18-1-1

Mixed

9-0-1

4-5-13-6-12-9-1

* 3 replications of each mixture.

** 2 replications of each mixture.

*** 3 replications of each mixture prepared for non-compaction treat-ments.

Batios are given in the order of samd, clay soil, and peat*Components of the mixtures were measured on a volume "basis •

12

applications to assure a fairly uniform coverage. A similar soil

aggregate analysis determination was made of the conditioner treated

soil after having "been stored in a container for 21 months and percent

of aggregation -was above 99 percent (uncorrected for primary particles).

When the conditioner treated soil had been air-dried, the

clay soil aggregates, like the concrete sand, were sieved into five

different sizes. Because of the small amounts of very small aggregates

present (less than 0.5 millimeter), a limited amount of grinding of

larger soil aggregates was done to supply additional amounts of the two

smaller aggregate sizes.

A black cultivated sedge peat was obtained from the Eli Colby

Peat Company. Because of the fineness of this material, it was not fea-

sible to separate out the different particle sizes. What significance,

if any, this had on the outcome of the experiment is not known.

Various mixtures of sand, clay soil, and peat were prepared as

shown in Table 2. The materials were thoroughly mixed and then trans-

ferred to the 5 quart containers. Even with precautions taken to assure

a homogeneous mixture, there appeared to be some segregation, probably

due to differences in weight, of sand and clay particles when mixtures

were poured into the embedded containers.

Cores of approximately 3 inches in diameter of T-35A Bermuda

grass were obtained from the Agronomy turf plots. Soil was carefully

removed from each core by washing. Grass from a single core with soil-

free roots was planted in the mixture of each container. Grass was

planted in the middle of September of 195^. Although planted late in

the year it became fairly well established by the time dormancy set in.

13

General maintenance practices:

Other than the compaction and high moisture treatments, man-

agement practices were quite similar to those employed on the average

golf course. There were occasional periods during examinations and

the like when an exacting routine was not followed, however, every

effort was made to keep these periods to a minimum.

The experimental area was normally irrigated two to three

times a week "by a swirling sprinkler. It was found that the grass in

the very sandy mixtures even in the summer months did not show signs

of wilting until k or 5 days after the previous watering. For the

last *K) days of this experiment water was applied for several hours

every night. It was thought that the heavy moisture treatment would

accentuate the effects of the previous compaction treatments.

Goldthwaite's IO-5-5 Turf Special was the only fertilizer

used throughout the experiment. An application at the rate of 1 pound

of IT, \ pound of P2O5, and •§• pound of K2O per 1000 square feet was

applied every 2 weeks during the growing season. This was limited

to one application pei* month when dormancy set in. Because of the

large amounts of water applied and because of the low exchange capacity

of some of the mixes, fertilizer was applied once a week at the pre-

vious mentioned rate during the heavy irrigation period.

At intervals of k or 5 days the grass growing in the embedded

containers along with the rest of the experimental green was clipped at

3/8th of an inch with a greens mower. This is the normal clipping

height for golf greens on the neighboring golf courses. Admittedly the

clipping intervals were long, "but intervals of 2 weeks or longer had to

be given to grass plants in the containers to allow for sufficient

growth to make a comparative clipping analysis.

Top dressing for the experimental green consisted only of the

material already present in the mixture. Its primary purpose in this

experiment was to retain a constant volume of soil mixture in each con-

tainer. It was applied only during the initial period of the experi-

ment when settling reduced the volume of the mixture and after each

compaction treatment when similar conditions had been produced. When

applying top dressing, precaution was taken to break up any layer of

organic residues that collected beneath the green vegetative surface of

the Bermuda grass.

Compaction treatments:

As was shown by various investigators in the literature re-

view, compaction of soil has a detrimental effect on plant growth.

There is also evidence that compaction frequently has an adverse effect

on the growth of turf on golf greens. Compaction of golf greens soil

mixtures is induced by player traffic, maintenance machines, and heavy

and frequent applications of water. To reproduce similar compacted

conditions in the mixtures of the embedded 5 quart containers in a

short period of time, it was necessary to compact these mixtures arti-

ficially. Due to the design of the experiment an impact type of com-

paction was chosen over other methods of compaction.

An impact device as shown in the top part of Figure 2 was con-

structed to compact the soil mixtures. The tamper and tamper rod and

handle weighed 10 pounds and the maximum falling distance for the tamper

was 18 inches. If the tamper handle was lifted until the tamper reached

CutawayVievof the

CompactingDevice

O Tamper Handle

Tamper Guide

Tamper Rod

Tamper

Bottom View of the Container Guard

Figure 2. A sketch of the compacting device and the container guara

16

the top of the guide and then allowed to fall freely, a compaetive force

of 15 foot-pounds was delivered to the sample with each drop. To pre-

vent the tamper from striking the metal container wall a guard was con-

structed from a 1 "by 9 inch board as shown in the bottom part of Figure 2.

Originally the plan had been to compact these mixtures with an

impact device at a moisture content that would produce the maximum den-

sity with a certain compactive effort. A procedure as outlined by Proc-

tor (35) to obtain the maximum density was followed with slight modifi-

cation. Moisture-density curves were plotted for all mixtures with var-

ying amounts of clay soil. Bouyoucos nylon moisture blocks were cali-

brated in these same mixtures by a gravimetric procedure. By plotting

micro-amp readings from the moisture meter versus percent moisture a

curve for each specific block and soil mixture was obtained.. These

blocks were then placed in the same mixtures in the field in which they

had been previously calibrated. By knowing the percent moisture at

which maximum density could be obtained with a certain compactive effort

as determined by the modified Proctor method, the exact time when this

moisture level was reached by each mixture could be determined.

This idea appeared excellent on paper; however, the applica-

tion was much more difficult than had been anticipated. Because of the

wide differences in clay content and water holding capacity of the soil,

a period of one week was required for all mixtures to reach the moisture

level for compaction at maximum density. Also there was a considerable

difference in moisture between the surface soil and the soil 6 inches

below the surface where the blocks had been placed. When the soil

around the blocks reached the moisture level at which maximum density

18

leaf clipper was employed. To insure uniformity of clipping height of

turf "between mixtures of different containers, all the clippings were

done "by one individual.

A thin 2 "by 2 foot sheet of alumin-im with a 6 3 A inch diam-

eter hole was placed over the embedded container so that the vegetative

growth from the container was exposed "but the surrounding area was

covered "by the sheet of aluminum.

Six clippings were made during the experiment. The initial

clipping was made prior to the compaction treatments. The next three

were taken during or after the compaction treatments and the final two

were taken during the heavy moisture treatment. The dates of the clip-

pings and yields of the mixtures are given in Tables k-9, inclusive, in

the Appendix.

Procedure for taking the undisturbed soil coress

Various physical measurements of a soil may he obtained with

ease when a sample of soil is taken in the form of an undisturbed soil

core. An apparatus, as shown in Figure 3> "was made for the specific

purpose of taking undisturbed soil cores from a golf green. To keep

from disturbing the cores when taking samples, the cutter head has a

slightly smaller cylindrical bore than the sample tube. This sampler

can be withdrawn from the soil without disturbing the surrounding area.

A complete description of the operation of a core sampler is given by

Russell (38). Core samples were taken only when soil moisture was at

or below field capacity. Because of the difference in moisture reten-

tion between mixtures, all cores could not be taken in one sampling

period. Cores from the sandy mixtures were taken first, and as the

19

Hole for Cou-pling Pin

Safety Ring

Soil Core Tube

Cutting Head

Figure 3« A cutaway diagram of the apparatus used for taking theundisturbed soil core samples.

20

soil mixtures "became drier, cores from the higher clay soil mixtures

•were taken. Undisturbed cores were packed in "waxed ice cream containers

of 1 pint capacity and taken to the laboratory for physical measurements

Sampling procedure for the soil aggregate analyses %

Approximately 200 grams of soil mixture from the top 2 or 3

inches were removed from each representative mixture. Samples from the

replications of each mixture were consolidated to reduce the sampling

error. Samples were allowed to air-dry in the field "before being taken

to the laboratory.

Removal of the roots from the soil mixtures:

The field work was terminated by the removal of the grass

roots from all the mixtures. After the excavation of containers, each

container was cut open. The mixture and the opened container were

placed in a wire basket, which was 8 inches in diameter and 10 inches

high. The basket was made of ij- inch hardware cloth and the sides of

the wire basket, but not the bottom, were lined with ordinary screen

wire. Once inside of the basket the opened container was removed. The

wire basket with contents was then placed in an empty 5 gallon paint

bucket and water was added until the sample was submerged. By gently

lowering and raising the sample in the water, the roots quickly became

separated from the soil mixture. Separation was rapid with sandy mix-

tures. When the clay content was high it was necessary to soak longer,

even overnight, to facilitate removal of soil from the roots.

After the large volume of soil had been removed, the contents

were placed in an 8 by 12 inch screen wire bottom tray. Here the roots

21

were washed with a very fine stream of water under high pressure until

all visible foreign matter had "been removed from the roots, The clay

aggregates in the mixture gave very little trouble when 60 percent or

more sand was present in the mixture. Iron rust from the container had

an appreciable cementing effect on some of the sand particles, These

rather hard insoluble aggregates were the most difficult to wash out.

After being washed clean, the root samples were spread out on newspaper,

air-dried, taken to the laboratory, oven-dried at 115° C for 36 hours,

and weighed.

Laboratory Procedure

Both undisturbed core samples taken with the sampler described

and laboratory compacted samples were analyzed by a series of soil physi-

cal measurements. By compacting the soil samples, it was possible to

differentiate between good and poor mixtures on the basis of their physi-

cal properties.

A procedure for testing laboratory compacted mixtures con-

sisted of bringing the sample to field capacity, placing it in 2 inch

copper tubes, and compacting it at 20 pounds per square inch in a hy-

draulic press. With low compactive forces a moisture level of about

field capacity presented the optimum conditions for packing the soil to

maximum denseness* It was found that when pressure was accompanied by

a slight vibration, a considerable reduction in volume was produced

which was not produced by pressure alone. The vibrations were continued

until additional vibrations produced essentially no changes in volume.

It was found that the physical measurements of the samples after being

treated by this method were much more consistent in magnitude than the

22

samples receiving a pressure treatment only. Also with the vibration

the reduction in pressure from 50 to 20 pounds per square inch did not

significantly lower the hulk density if the samples were sufficiently

moistened•

The artificially compacted cores were then placed in water

for a minimum time of 6 hours or until such time that the cores were

thought to he completely saturated.

Permeability measurements:

Generally it is recognized that a good golf green soil mixture

must he moderately permeable. This characteristic facilitates the dis-

charge of excess water and the movement of gases to and from the plant

roots. The permeability of soil may he measured "by the amount of water

passing through a soil core sample. The permeameter used for the per-

meability determinations is shown in Figure h. It was found to he very

important for the permeameter units to have an adjustment whereby the

head could "be accurately maintained between different samples. With two

identical sandy soils a difference of a fraction of an inch of head can

produce a large difference in the infiltration rates. With the unit

shown it was possible to adjust the head very accurately and precisely.

A -J- inch head was used for all determinations.

Permeability determinations were made over a period of 6 hours

after saturation. Although this short period of time does not present a

true picture of the infiltration rates at equilibrium, as shown by

Garman (15)> it does give a value that may be used in comparing similar

samples which have been treated alike. Even with the fine adjustments

of the permeameter unit and the homogeneous soil mixtures used this

23

Fine Adjustment forHeight of Bead

Water Outlet

M6dlfi«a 2 W

Spud Washer

2" Diameter CopperSampling Tube

Modified 2"Spud Washer

Water Irtflov

Figure k* A cutaway diagram of the permeameter unit used for measuringthe infiltration rates through the undisturbed soil coresamples•

2k

method "by itself is limited "by the intricacies of the physics of

flow around micro soil particles.

Porosity measurements:

Both capillary and non-capillary porosity determinations were

made on a gravimetric basis. The separation between these two is made

on the basis of the amount of water retained by a soil after a certain

amount of tension or suction is applied. Baver (l, page 269) stated

that a tension of ̂ 0 cm. gave the best agreement between percolation

rates and porosity. A procedure and apparatus as described by Learner

and Shaw (23) were used to determine the non-capillary porosity or large

pore space. The volume of water not removed by this tension divided by

apparent volume of the sample or core is classified as the amount of

capillary porosity or small pore space. Russell (38) in his review of

methods of measuring soil structure gives a clear description of the

procedure for determining soil porosity.

Soil aggregate analyses:

The wet sieve method as described by Yoder (kf) and reviewed

by Russell (38) was used for all aggregate determinations. It was found

necessary to reduce the sample size from 50 to 25 grams when aggregation

of single particle size mixtures was determined. With the standardized

procedure the large volume of particles on some sieves seemed to distort

the true distribution of aggregate sizes.

25

RESULTS

The various physical measurements of the soil mixtures mean

very little unless in some way they can be related to the amount of

root and top growth produced. Although the foremost objective was to

find a soil mixture that would produce the largest root and clipping

yield, the soil physical characteristics that were associated with the

yields produced were also given considerable attention.

Although there were three replications of three particle size

soil mixtures, namely 5-2 mm., 2-1 mm., and mixed, only two replications

were used when a comparison was made between all five individual par-

ticle sizes. This limitation was brought about by having only two

replications of sizes, 2-1 mm. and 0.5-0.25 mm. The homogeneity of the

data in most cases appeared to be such that the loss of one replication

for the aforementioned three mixtures did not create any major uncer-

tainties as to the outcome of the statistical analyses. The two rep-

lications for any analysis were always randomly selected.

The clipping and root yield data and all the physical measure-

ments of the mixtures discussed in the results are listed in Tables 5-l8

inclusive, in the Appendix.

Clipping Yield Data

To make certain that some growth factors were not favoring

growth on certain particle size mixtures or mixtures of varying clay eon

tent before compaction treatments were begun, a clipping was taken prior

to all compaction treatments. These data are presented in Figures 5

26

3,0..

2.0-.Weight ofClippingsin Grams

1.0J

5-2 mm. 2-1 mm. 1-0.5 ^m. 0.5-0,25 mm. MixedParticle Size of Soil Mixtures

Figure 5. Average clipping yields of top growth, removed prior to com-paction treatments, from mixtures of different particle sizes.Each bar represents an average of 8 observations.

3.0.

2.Q.

Weight ofClippingsin Grams

l.CLl

L.S.D. at .05 s .

6-3-1 7-2-1 8-1-1Sand-Clay Soil-Peat Ratios

Figure 6, Average clipping yields of top growth, removed prior to com-paction treatments, from mixtures of different sand-claysoil-peat ratios. Each bar represents an average of 10 ob-servations.

As may "be readily seen from observing the bar graphs, there is

very little difference in the yields between the averages for the dif-

ferent particle size mixtures and even less difference between the aver-

ages for the mixtures of varying clay content <, At the time of the ini-

tial clipping, grass plants had been in the soil mixtures for a period

of 9 months. No differing growth response between the various mixtures

was evident.

Figures 7 and 8 indicate that the same general trends in clip-

ping yields exhibited by the various particle size mixtures and ratios

after the compaction treatment were also present during the high mois-

ture treatments. The small yields exhibited by the larger particle size

mixtures in Figure 7 appear to have been caused by several factors*

There appeared to be considerable more mutilation of stems and leaves in

the 5-2 mm. and 2-1 mm. particle sizes due to compaction; hence the

small yield produced immediately after compaction by these mixtures was

understandable. It was thought that plants on these larger particle size

mixtures might recover during the final stages of the experiment, but a

comparison of the data shown in Figure 7 shows no apparent change in the

yield between mixtures.

The effect of ratios on the clipping yield of different par-

ticle size mixtures is shown in Figures 9 and 10o Figure 10 indicates

that as clay content became less within the particle size mixtures a

greater range of yields was produced» Therefore in golf green soil mix-

tures with low clay contents particle size becomes extremely important«

With the l-0»5 inm. and mixed particle size mixtures as shown in Fig-

ure 10, ratios with decreasing clay contents produced statistically

28

3.0.

2.0-Weight ofClippingsin Grams

1.0J

Clipping Yield afterCompaction.L.S.D. at .05 = .30

Clipping Yield after Com-paction and during the High.Moisture Treatments.L.S.D. at .05 = .1+0

5-2 mm. 2-1 mm. 1-0.5 mm. 0.5-0.25 mm. Mixed

Particle Size of Soil Mixtures

Figure 7» An average of 2 clipping yields to top growth, removed afterthe compaction and during the high moisture treatments, frommixtures of different particle sizes. Each bar representsan average of 16 observations.

3.0^

2.0Weight ofClippingsin Grams

1.0 J

Figure 8,

Clipping Yield afterCompaction.L.S.D. at .05 = .27

6-3-1

Clipping Yield after Com-paction and during the HighMoisture Treatments.L.S.D. at .05 = .36

7-2-1 8-1-1 Uo-'o'

Sand-Clay Soil-Peat Ratios

An average of 2 clipping yields of top growth, removed afterthe compaction and during the high moisture treatments, frommixtures of different sand-clay soil-peat ratios. Each barrepresents an average of 20 observations.

29

3.0

2.0 J

Weight ofClippingsin Grams

1.0 .

3.0-

2.0

Weight ofClippingsin Grams

1.0

a • 5"*2 TBHlo

(T) — Q 2-1 ram,X —X 1-0*5 EMUA A 0.5 - 0.25 mm.0 — 0 Mixed

6-3-1 7-2-1 8-1-1

Sand-Clay Soil-Peat Ratios

Figure 9. Differential effects of the different sand-clay soil-peatratios of 5 particle size mixtures on yields of 2 clippingsfollowing the compaction treatments.

-A-

•"^ • 5-2 mm.0 — E ) 2-1 mm.X — X 1-0.5 T®®*A—A 0.5-0.25 mm.0 0 Mixed

6-3-1 7-2-1 8-1-1

Sand-Clay Soil-Peat Ratios

r-i-1

Figure 10, Differential effects of the different sand-clay soil-peatratios of 5 particle size mixtures on yields of 2 clippingsfollowing the compaction and during the high moisture treat-ments.

30

significant increases in clipping yields.

The fact that compaction is not always harmful and in some

cases may "be most desirable is clearly shown in Figure 11. It may be

noted that the clipping yield from the 0-9-1 ratio was reduced consid-

erably when compacted. The 6-3=1 ratio showed very little change in

yield under compaction and the remaining mixtures showed large increases

in yield under compactiono The order of increase in clipping yield

follows closely in the reduction of clay content. Apparently consoli-

dation of soil particles plays an important part in various root func-

tions if it does not produce other physical limitations in aeration and

permeability.

Root Weight Data

It was found generally that the total root weight increased as

particle size decreased*, Figure 12 shows the average root weights of

the various mixtures <. The differences between the /arious mixtures were

found to be significant at the .01 level. Additional evidence support-

ing the apparent relation between small particle sizes and increased root

weight is given by the data for the less than 0o25 mm. particle size mix-

tures. These data are presented in Table 11 in the Appendix,, These mix-

tures had the largest amount of roots of any mixture in the experiments;

however, they were not included in Figure 12 because of an insufficient •

number of samples. Another interesting feature shown in Figure 12 is

that although the mixed particle size mixtures contained all particle

sizes, the amount of roots produced was less than that produced by any

of the uniform size component mixtures.

31

3.0 J

Weightof

Clippingsin Grams

0

\

\

\

\

\X0— — —0- — —0—

0 © Hon-compacted Mixed Particle Size Mixtures

X X Compacted Mixed Particle Size Mixtures

..0J

o-9-l 6-3-1 7-2-1 8-1-1

Sand-Clay Soil-Peat Ratios

Figure 11. Tlxe effect of various sand-clay soil-peat ratios of the com-pacted and npn-compacted mixed particle size mixtures onyields of 2 clippings taken during the high moisture treat-ments.

3CO*

CO

yyyyyyyyyyyyyyyyyyyyyyyy

yyyyyyyyyyyyyyyyyyyyyyyyyyyy/

/yyyyyyyyyyyyyyyyyyyyyyyyyy/

yyyyyyyyyyyyyyyyyyyyyyyyyy/

yyyyyyyyyyyyyyyyyyyyyyyy/

CVJ

OJr

oCO

CJ

84*

4*

foITvH

Lf\

O

21T\

MoCO

HCVJ

CO

•S

Ito•HCQ

4!O•H

fCQ49g g

oa

4>ow4> 49O

O

0) O

toaO4>U

a)4}op43

O

33

Actually the total root weight in these samples included "both

the crown and the roots. It may have been possible to obtain more re-

liable data had the roots been severed from the crown after washing. In

Figure 13, roots of the various particle size mixtures are shown. It is

interesting to note the extensive branching of the roots in the coarser

particle size mixtures and the decrease in branching for the progres-

sively smaller particle size mixtures. Considerable effort was made to

select one of the longer roots in each mixture. Figure 13 indicates

that root length increased as particle size decreased which may partly

explain the additional root weight found in the finer textured samples.

An analysis of the root weights in the undisturbed cores indi-

cated a significant difference between particle sizes and showed much

the same trend as was exhibited by mixtures in Figure 12. Since the

cores were removed from the upper M=r inches of the profile where the

compactive forces were at a maximum, it seemed logical that some evi-

dence of an abnormal distribution of roots should have appeared between

particle mixture sizes or even ratios. Such a difference was not ob-

served.

Another interesting aspect of the root study was a comparison

between root yields of several mixtures under compacted and non-com-

pacted conditions. The results of this analysis are given in Figure lkm

With the exception of the 0-9-1 mixture, the root yields between com-

pacted and non-compacted mixtures seem to show very little effect either

directly or indirectly as a result of compaction. When a change in

yield occurred due to clay content in the compacted mixture, the iden-

tical change occurred in the non-compacted mixture.

Figure 13. Typical examples of roots found in mixtures of various particle sizes.

35

30.0.

a

25.0 . --©

20*0.

WeightOf Roots

in Grams

15.0.

10.0 _

0 © Non-compacted Mixed Particle Size Mixtures

X — • X Compacted Mixed Particle Size Mixtures5.0.

0-9-1 6-3-1 7-2-1 8-1-1

Sand-Clay Soil-Peat Ratios

Figure lk» The effects of the sand-clay soil-peat ratios of the compactedand the non-compacted mixed particle size mixtures on totalroot weight.

By comparing Figures 11 and 1^, it may be seen that there

were rather large differences in root and top growth responses of these

mixtures. Only in the 0-9-1 sample did a positive relationship exist

between root and top growth.

Porosity Data

Although measurements of total porosity indicated only small

differences between the compacted mixtures, measurements of capillary

and non-capillary porosity varied over a considerable range between the

mixtures. The capillary and non-capillary porosities of the sand-clay

soil-peat ratios also were found to vary within a particle size mixture,

Data for non-capillary, capillary, and total porosity are presented in

the same order in Tables 12, 13, and 1^ in the Appendix.

A definite amount of non-capillary porosity appeared to be

especially important in terms of thQ amount of top growth produced. It

was found that when the clay content of the mixture was low, non-capil-

lary porosity usually was large; hence in those soil mixtures, moisture

was likely to be much more limiting than aeration. Usually 10 to 15

percent non-capillary porosity was associated with high clipping yields,

Some mixtures obviously had other limiting factors that reduced growth

even though the apparent optimum non-capillary pore space conditions

were present.

The 1-0.5 mm. and the mixed particle size mixtures showed the

best linear relationship between clipping yield and non-capillary poros-

ity. By plotting non-capillary porosity versus the clipping yield as

shown in Figure 15, a positive regression coefficient of .2*1-9 and a

highly significant correlation coefficient of .65^ were obtained. This

37

25.0,

20.0,

TotalClippingYieia inGrams

10.0.

5.0.

0

A

1-0,• 5 ram. Particle Size Mixtoares

Mixed Particle Size Mixtures

-*—3T

1

©o ©

-

! 1 !5 io 15 20

Percent Non-capillary Porpsity

Figtare 15 • The relationship "between the total clipping yield of the1-0.5 ™ u and mixed particle size mixttires and the non-capillary porosity.

38

indicates that for specific mixtures involved, there was generally an

increase in yield with each increase in non-capillary pore space. It

appears from observing Figure 15 that other factors "became limiting in

the 1-0.5 mm. size when non-capillary porosity exceeded 15 percent. It

was found that in the non-compacted high clay soil mixtures as much as

18 percent non-capillary pore space appeared to be ideal. Because of

the characteristics of the high clay soil mixture in a non-compacted

state, other apparent limitations were not present. Overall significant

differences in non-capillary porosity were found in particle size mix-

tures and also in the various ratios. These differences are exhibited

in Figures 16 and 17*

The trend in capillary pore space exhibited by the soil mix-

tures was almost exactly opposite to that of the non-capillary pore

space. It appeared that only in a few mixtures did the lack of capil-

lary porosity become a limiting growth factor.

It may be of interest to note the changes created in the per-

centage of large and small pores when a soil is compacted. Capillary

and non-capillary porosities of identical samples, half of which were

"compacted, are shown in Figure l8» Actually capillary pore space was

increased by compaction with all soil mixtures; however, non-capillary

pore space was reduced up to three-fourths of the original amount.

With the significant reduction of large pores, the downward movement of

water and air are restricted, nutrient and water absorption of the roots

are reduced, and hence, growth is impeded.

Soil Aggregate Analysis Data

When Houston Black clay soil was stored in a cardboard, waxed

39

15

10.0.

PercentIf on-cap-illary

Porosity

5-2 vm 1-0.5 ma, 0» 5-0*25 mm. MixedParticle Size of Soil Mixtiares

Figure l6« The effects of the compacted mixttares of different particlesizes on the non-capillary pore space» Each "bar representsan average of 8 observations

15,0_

10.0

PercentHon-cap-illary

Porosity

-3-1 7-2-1 8-1-1Sana-Clay Soil-Peat Ratios

Figure 17 *Ehe effects of the compacted mixtures of different sand-claysoil-peat ratios on the non-capillary pore space* Each "barrepresents an average of 10 observations*

60.0

5Q.0-

1*0*0.

PercentPorosity

30.0^

20,0 _

10,0

Capillary PorosityX ~ X Non-compacted MixturesX = )( Compacted Mixtures

Non-capillary Porosity0 0 Non-compacted Mixtures

® = © compacted Mixtures

-O—

VY -

—0

O-9.1 6-3-I 7-2-1 8-1-1

Sand-Clay Soil»Peat Ratios

Figure 18* The effects of the coinpaction treatments on the capillary andthe non-capillary porosities of the mixed particle size mix-tures •

container for 21 months after having been treated with a soil condi-

tioner at 2000 pounds per acre, it was found that the treatment pro-

duced a nearly completely aggregated soil (uncorrected for primary

particles). When the aggregates of Houston Black clay soil were in-

corporated into various soil mixtures which received high moisture an<3

compaction treatments, both increases and decreases of aggregation were

observed. This is shown graphically in Figure 19.

It was found as shown by the bar graphs of Figure 19, that

soil mixtures with 30 percent or more of clay soil by volume showed

less aggregation with or without compaction than was predicted when the

mixtures were prepared. With 10 percent and less clay soil by volume

mixtures with and without compaction were found to have a larger per-

centage of aggregation present than when the mixtures were prepared.

Compacted mixtures with 10 percent and less clay soil had a larger per-

centage of aggregation than non-compacted mixtures.

Although percent of aggregation remained constant or increased

in some instances, it should not be assumed that all aggregates present

initially were still present as such when the aggregate analyses were

made. Probably all aggregates or portions of aggregates were broken

down or dispersed in some form or another. This theory is supported by

the large percentage loss of aggregates in the 0-9-1 mixture as shown by

Figure 19 and by the decrease of the large aggregate size in all mixtures

as shown Try Figures 20 and 21. In many cases sand grains became enmeshed

with the aggregates resulting in large increases of aggregate weight

which probably explains some of the increases noted. Because of the

absence of sand particles and dispersion of some of the soil aggregates,

k2

loo.

90-

80.

TO

60

50PercentAggre-

30

20

10.

Figure 19»

0-9-1

XXX_̂

CalculatedPercent ofAggregationfor PreparedMixtures

Percent ofAggregationin the Non-compactedMixturesafter Ter-mination ofExperiment

/

Percent ofAggregationin the Com-pacted Mix-tures afterTerminationof Experiment

71//

6-3-1 7-2-1 8-l»lSand-Clay Soil-Peat Ratios

A comparison of the percent of aggregation, in pre-pared mix-tures? "before and after these mixtures had undergone fieldtreatments.

kk

70 •

60

50-

Percentof Total

Aggregates 30Present

20

10-

\

\

\

Q Non-compacted 0-9-1 Mixtures

0 Compacted 0-9-1 Mixtures

O

>2 mm* mm* mm*ram. >0.5 ram,Aggregate Size

Figure 20. A comparison of the aggregate size distribution between thecompacted and the non-compacted 0-9-1 mixtures*

50

koPercentof Total

AggregatesPresent

20.

10

Non-compacted Mixture Averages of6-3-1, 7-2-1, 8-1-1, and ^ ^

Compacted Mixture Averages of6.3-1, 7-2-1, 8-1-1, and

©

7 \

\o

>2 mm. >1 mm. >0.5 mm. >0.25 mm* >0,l mm*

Aggregate Size

Figure 21. A comparison of the average aggregate size distribution be-tween the 6-3-1, 7-2-1, 8-1-1, and 8j-|--l compacted and non-compacted mixtures.

an increase in aggregation did not occur in the mixtures of high clay

content under any circumstances. In the mixtures of low clay soil con-

tent it appeared that the sand particles engulfed by the soil aggre-

gates had such a dominating effect on increase of aggregate weight that

the soil aggregates lost through dispersion appeared to be negligible.

It is quite likely that upon dispersion some downward move-

ment of the finer soil fractions occurred. Because of the small amount

of clay soil initially present in some of the mixtures, a good technique

in the mechanical analysis of soils and several determinations per mix-

ture would be obvious prerequisites for detecting such small differences.

However, with a less aggregated soil downward movement of the finer frac-

tions may be visibly observed in laboratory compacted mixtures.

Additional evidence, adding to the idea as mentioned previously

that aggregates did not remain unchanged in size but were broken down,

is shown in Figures 20 and 21. In order that a comparison might be made

between Figures 20 and 21 the values for both figures were plotted on a

basis of the percentage of the total aggregates present. Figure 20 shows

the effects of compaction on aggregate size of the 0-9-1 mixtures* Upon

compaction of one or two identical groups of mixtures there was a de-

crease of aggregates larger than 2 mm. and an increase of all aggregates

smaller than 2 mm. When rather large amounts of various size sand par-

ticles were present, the aggregate size and the relationship between

compacted and non-compacted mixtures were not quite so obvious. This is

shown in Figure 21.

Because the various sand-clay soil-peat ratios with 60 percent

or more sand showed a very similar relationship in the aggregate size

distribution, an average was taken of all the values. It can he seen

that these values do not coincide with those of Figure 20. The most

significant differences of Figure 21 are piobably the predominance of

the greater than 0.25 Kjm» size, the reduction of the greater than 2 mm.

size, and the rather obvious insignificance of the effects of compac-

tion on aggregate size distribution. The remaining three sizes in

Figure 21 do not vary much from the percentage of the 0-9-1 mixtures

shown in Figure 20. It appears likely that either the greater than

2 mm. size aggregates broke down into the greater than 0.25 ^m. size,

or the latter had a greater stability than any other size present. Un-

like the relationship in Figure 20, the interchanging relationship be-

tween the size distribution of the compacted and non-compacted mixtures

in Figure 21 gives some indication of the complexity of the principles

governing aggregate stability,. It is possible that the differential

wetting and drying which is accentuated by the presence of an inert and

porous system such as sand may stimulate the formation of smaller aggre-

gates. The evidence in Figure 21 indicates that the effects of compac-

tion on aggregate size distribution were rather mild compared to the

less obvious, but seemingly quite influential, effects that the sand had

either directly or indirectly on the clay aggregates during a 21 month

period of association.

The large amounts of water applied surely were not conducive

to aggregate stability. It is quite likely that the dispersing effects

of water infiltrating rapidly through the non-compacted soil mixtures

were responsible for the breakdown of the larger aggregate sizes in the

non-compacted mixtures.

Bulk Density Data

The "bulk density determinations were of very little signifi-

cance in evaluating the over-all fitness and productiveness of the soil

mixtures. Although a trend in l;he magnitude of the average bulk density

•was found between ratios over all particle size mixtures, variations

within the replications of any one ratio were frequently as large as the

variations between ratios. Because of the relative homogeneity of most

of the mixes and because of the equality of the amount of compaction

imposed on each mixture, the range of the bulk density for the mixtures

that appeared to be most promising was very small. Consequently any

small experimental error greatly enhanced the possibility of getting er-

roneous results. Evidence was found that the variable amounts of roots

found in the soil cores was a major factor in the inconsistencies found

in the bulk density measurements.

Because of the wide differences of the bulk densities between

sand, clay soil, and peat and because of the profound differences in

their physical properties, the selection of a soil mixture on the basis

of its bulk density alone appears to be unsound. However, together with

a number of other physical measurements, bulk density measurements may

be helpful in characterizing a soil mixture and in deciding upon its

fitness for golf green use.

Permeability Data

In general it was found that the permeability rates, though

quite variable, decreased as clay content increased and as particle size

decreased. In a preliminary investigation on permeability the same mix-

tures that were compacted in the field were compacted at 20 pounds per

square inch in the laboratory* Mixtures were compacted in the same cyl-

inders in which the core samples were taken. Much less variation in the

permeability rates was found in the laboratory compacted mixtures than

in the field compacted mixtures * Some of the variation in the latter

may he due to the quantity of roots present in the core, the presence

of organic residues from dead roots, dispersion of the soil aggregates,

or poor core sampling technique. The fact that most of these conditions

were completely absent in the laboratory compacted samples is sufficient

evidence to explain why there was much better agreement in the results

of the laboratory compacted mixtures«

Many precautions were taken to insure accuracy and precision

in the permeability determinations, but the physical characteristics of

the soil mixtures, the root structures therein, and the other factors

produced such a complex medium that only very general conclusions were

obtained from the permeability data*

14-8

DISCUSSION

Variation of Root and Top Growth "between Various Mixtures

One of the most interesting observations made was the com-

parison "between root and top yields from various particle size mixtures*

It is generally an accepted fact that within a species the extent of the

root system has a profound influence upon the quantity of top growth

produced. The root system itself may vary in number of roots, weight,

structure, and direction of growth depending upon the conditions under

which the plant was grown* Much work has been done in investigating the

various factors affecting root and top growth. Temperature, aeration,

moisture, nutrient supply, and other plant environmental factors have

"been shown to affect root and top growth.

In spite of the recognition of these growth factors, it is

difficult to ascertain what stimulated root growth in some soil mixtures

of this experiment. Where progressively smaller particle size soil mix-

tures receiving similar maintenance treatments produced increasingly

larger root yields one would conclude that particle size did affect the

root environment and thus root growth. Because non-capillary pore space

was as low as 3 percent in the highest root yield mixtures, lack of aer-

ation did not appear to "be a prime factor in root growth. Clipping

yield on the other hand appeared to "be affected much more "by lack of

aeration than root yields. Because of the closely controlled mainten-

ance practices it seems unlikely that fertility, moisture, and tempera-

ture factors were important. In this experiment it appears that in mix-

tures with the smaller uniform particle sizes, the impeding mechanical

forces pushing against the root were distributed over a larger area and

thus reduced the possibility of a critical pressure being exerted on

any particular portion of the root. If aeration is not limiting under

the circumstances, it is possible that the smaller pore size compared

to the larger pore size had a more favorable influence on root growth*

A comparison of the root and clipping yields of the various

particle size mixtures as shown in Figures 7 an^ 12 showed a differen-

tial response in root and top growth with respect to several mixture

sizes. Because of the greater denseness and consequently less pore vol-

ume for root growth in the mixed than in the uniform particle size mix-

tures, the extent of root growth in the mixed particle size mixtures was

probably adversely affected. In light of these conditions it is diffi-

cult to explain the higher clipping yields obtained. It is possible

that because of the slight consolidation and more rigidness in the mixed

particle size medium, better contact was maintained between the soil and

roots resulting in a greater efficiency of nutrient and moisture absorp-

tion per active unit area of absorbing root. However, it is possible

that still other environmental conditions may have contributed to the

differential response in root and top growth.

Admittedly the above suggestion may not be sound and addi-

tional work will be needed to substantiate or disprove it. If found to

be valid, the idea could undoubtedly be used in many applied situations

that demand a characteristic type of grass growth to best overcome

problems confined to certain areas or imposed on the turf through vari-

ous maintenance practices. For example, in a soil mixture that encour-

ages deeper root growth, the number of water applications could be re-

duced, or in a green with a very shallow root zone there may be an

advantage of selecting a particle size mixture that would stimulate

top growth.

Effects of the Modified Physical Soil Properties

on Root and_ Tojp Growth

The seemingly indifferent response to the high moisture treat-

ments was not anticipated, The heavy rates of water application did

not appear to limit growth. Drainage appeared to be quite adequate so

that no harmful effects resulted.

Compaction was found to "be "both harmful and beneficial in terms

of top growth depending upon the type of soil mixture being compacted.

It appears by analyzing the clipping yields (Figure ll) that mixtures

above JO percent sand by volume were greatly benefited by the compac-

tion j compacted mixtures of 60 percent sand by volume showed very little

change from the clipping yield of the non-compacted mixtures; and com-

pacted mixtures with no sand at all exhibited large reductions in the

clipping yields compared with the non-compacted mixtures.

Again the idea that the consolidation or rigidness of the me-

dium retarded root growth but enabled the plant roots to maintain better

contact with the minute particles of the sandy soil mixtures appears to

be the most logical explanation for the large increases in the clipping

yield of the compacted over the non-compacted sandy soil mixtures. Be-

cause the non-compacted sandy soil mixtures had a greater non-capillary

porosity and because there was less consolidation of the soil mixture,

aeration and mechanical impedance evidently were not factors in the re-

duced clipping yield of the non-compacted sandy mixtures. Because of a

slightly greater amount of aggregate breakdown in the compacted sandy

soil mixtures and consequently a greater availability of chemically

active soil surface area from -which the plant roots could extract

additional nutrients and moisture, top growth may have "been somewhat

accelerated in the compacted mixtures.

On the other hand in the compacted 0-9-1 mixtures, aeration,

water infiltration, and mechanical impedance appear to have contri-

buted to reducing the clipping yield. The highest clipping yields

among all mixtures tested were obtained from the non-compacted 0-9-1

mixtures. An investigation of the various physical properties of these

mixtures, given in Tables 12-17, inclusive, in the Appendix, will fur-

ther substantiate the importance of the physical properties of a soil

mixture in the over-all productiveness of the grass plants.

Root yield comparisons between the compacted and the non-

compacted mixtures (Figure 1̂ -) indicate that compaction treatments defi-

nitely reduced root yields under all clay soil contents. The largest

difference in the yield was found in the 0-9-1 mixture. Because of the

exact parallelism of the remaining portions of the two curves, there

is a strong indication that compaction had a small, yet equal, depress-

ing effect on the root yields.

Mechanical impedance, clay content, and aeration or associ-

ated effects appeared to have been the most outstanding factors affect-

ing plant growth in this research. In most cases the growth factors

were so interrelated as to make it essentially impossible to evaluate

the effects of any one factor. The interactions of the three factors

were again reflected in the differential growth responses of roots and

aerial organs of the grass plants. Much more fundamental research is

needed to be able to properly ascertain the quantitative effects of

these factors on all phases and regions of plant growth.

53

SI3MMARY AHD CONCLUSIONS

Synthesis of a soil mixture that would resist the effects of

compaction and high moisture and simultaneously possess the maximum

qualities that would "be conducive to good turfgrass growth was the pri-

mary objective of this experiment. Clipping yields and root yields were

used as yardsticks in selecting a desirable mixture. A study of the

various sand and clay aggregate sizes and of the different clay levels

affecting the physical properties of the mixture was made. Mixtures

studied were compacted "both in the laboratory and under field conditions.

Golf green soil mixtures supporting plant growth in the field were sub-

jected to compaction and high*treatments, but otherwise their mainten-

ance was similar to that used on neighboring golf courses.

From this experiment with the material used and under the con-

ditions described the following concluding statements can be made:

1. On the basis of the amount of top growth produced, a uni-

form 5-2 mm. size and the uniform 2-1 mm. size do not appear to be de-

sirable for golf green use, whereas mixed particle size and the uniform

1-0,5 Esa» size appear to be the most desirable mixtures.

2. Root growth, reaching a maximum in the less than 0.25 mm.

particle size mixtures, increased as uniform particle size decreased.

Mixed particle size mixtures retarded root growth.

3. Compacted soil mixtures of 5 to 10 percent Houston Black

clay soil by volume or 2 to h percent clay by weight produced the larg-

est yields of top growth and in most instances also produced the largest

amount of root growth.

km Compaction treatments were found to he both harmful and

"beneficial in terms of top growth produced and definitely harmful in

terms of root growth produced.

5. Ho relative differences in clipping yield between mixtures

were noted during the heavy watering period.

&*• Aggregation was both increased and decreased in compacted

and non-compacted mixtures. This differential response was affected by

both the amount of sand and the amount of clay soil present.

7. Non-capillary porosities of 10 to 15 percent generally

produced the highest clipping yields in the compacted mixtures; however,

in terms of root growth the specific size and the continuity of the pore

size seemed more critical than any measured amount of non-capillary pore

space.

8. When grass roots are present in the field compacted soil

mixtures, physical measurements of the cores of laboratory and field

compacted identical mixtures cannot be compared with validity.

Because of the wide variations in the inherent physical and

cheudcal properties of soils, precaution should be taken in generaliz-

ing or utilizing as applicable to all golf green soil mixtures the sug-

gested recommendations given herein. Houston Black clay soil is domi-

nated by montmorillonite) hence, it is to be expected that its physical

and chemical characteristics will differ considerably from those of a

soil dominated by either kaolinite, illite, or some other clay mineral.

Therefore it is important that before the suggested recommendations are

followed a thorough physical and chemical analysis be made of the soil

that is to be incorporated in a golf green soil mixture. By a com-

parison of the analyses of the Houston Black clay soil with that of

55

other soils and "by making the necessary adjustments for the differences

observed in the analyses, it is likely that a much more satisfactory

mixture may be obtained. Additional and much more fundamental research

involving mixtures of other soil types, skeletal agents, and peats is

needed •

REFERENCES

1. Baver, L. D. Soil Physics* Third Edition. John Wiley and Sons,Inc. Hew York, 1956.

2. Barer, L. D. and Farnsworth, R. B. Soil structure effects in thegrowth of sugar "beets. Soil 3ei. Soc. Am. Proc ^ ^ 8

3« Bertrand, A. R. and Kohnke, H. Subsoil conditions and their effectson oxygen supply and the growth of corn roots. Soil Sci. Soc.Am. Proc. (in press).

K* Bouyoucos, J. G. Hewly developed nylon units for measuring soilmoisture in the field. Highway Research Abstracts, MichAgr. Exp. Sta. ^

5. Boynton, D. and Compton, 0. C. Effects of oxygen pressure inaerated solution on productivity of new roots and on growthof roots and tops of fruit trees. Proc. Am. Soc. Hort. Sci.42:53-58. 191*3 •

6. Brown, E. M. Some effects of temperature on the growth and chemi-cal composition of certain pasture grasses. Mo. Agr. Exp.Sta. Research Bull. 229. 1939*

7» Bryant, A. E. Comparison of anatomical and histological differ-ences "between roots of barley grown in aerated and in non-aerated culture solutions. Plant Physio. 9:389-391« 193^#

8. Cannon, W. A. Influence of the temperature of the soil on therelation of roots to oxygen. Sci. 58:331-332. 1923.

9. de Ropp, R. S. Studies in the physiology of leaf growth. III.The influence of roots on the growth of leaves and stems inrye. Ann. Bot. (lTS)lO:353-359« ^6

10. Doneen, L. D. and Henderson, D. W. Soil conditions affectinginfiltration of water and root development. Am. Soc. SugarBeet Tech. Proc. 7:2llj-223. 1952.

H . Erickson, L. C. Growth of tomato roots as influenced by oxygenin the nutrient solution. Am. Jour. Bot. 33:551-561.

12. Evans, T. W. The root development of New Zealand brown top,Chewingfs fescue, and fine-leaved sheep's fescue under put-ting green conditions. Jour Board Greenskeeping Res.(Great Britain). 2:119-12l|.. 1939.

57

13* Free, G* R», Lamb, J* Jr*, and Carleton, E* A* Compactibility ofcertain soils as related to organic natter and erosion*Jour. Am* Soc. Agron. 39:1068-1076* ^

Ik* Fribourg, H. J. A rapid method for washing roots* Agron* Jour*^ M 1953.

15* German, W* L* The permeability of various grades of sand and peatand mixtures of these materials vith soil and vermieulite*U. S. G. A* Jour* and Turf Management* 5-1:27*28* 1952*

16* Gilbert, G* S* and Shive, J* W« The significance of oxygen innutrient subtrates for plantst I* The oxygen requirements*Soil Sei* 53tl^3-152. ^

17. Gill, R* W* and Miller* R. D* A method for study of the influenceof mechanical impedance and aeration on the growth of seed-ling roots* Soil Sci* Soc. Am* Proc* 20:155-157* 1956.

18* Harper, J. C. Relationship of aerification, irrigation, and com*pact ion to phosphorus penetration* root development* andpopulation changes in a mixed turf of permanent grasses.PhD* Dissertation* Penna* State College* 1952*

19* Harris, F. S* The effect of soil moisture, plant food and age onthe ratio of tops to roots in plants* Jour* Am* Soc* Agron*6:65-75 • ^

20* Hubbell, P* S* and Gardner, J* L* Effects of aeration, compaction,and water logging on soil structure and microflora* Jour*Am* Soc. Agron. tot 832-6^0 . 19^8*

21* Knight, R* C* The response of plants in soil and in water cultureto aeration of the roots* Ann* Bot. 38:305-325* 192^*

22* Kunze, G* W« and Templin, E* H* Houston Black clay, the typegruumsol: II* Mineralogical and chemical characterization*Soil Sci* Am* Proc* 20:91-96. 1956*

23* Lawton, K. The influence of soil aeration on the growth and absorp-tion of nutrients "by corn plants* Soil Sci* Soc* Am* Proc*10:263-268. 19^5*

2k* Learner, R* W* and Shaw, B* T* A simple device for measuring non-capillary porosity on an extensive scale* Jour* Am* Soc*Agron. 33:1003-1008. 19>H.

25* Leonard, 0* A* Cotton root development in relation to naturalaeration of some Mississippi BlacKbelt and Delta soils* Jour*Am* Soe* Agron. 37:55-72* 19^5*

26• Loehwing, W« F. Physiological aspects of the effect of con-tinuous soil aeration on plant growth. Plant Physio.9:567-583* *

27. Lunt, 0. R. and Wyekoff, G. A method for minimizing compactiontinder turfgrass used for athletic areas. Agron. Jour,(in press).

28. Lutz, J. F. and Learner, Ro W« Pore size distribution as relatedto the permeability of soils. Soil Sci. Soc. Am. Proc.^:28-31. 1939.

29. Lutz, J. F. Mechanical impedance of plant growth, kk-72. SoilPhysical Conditions and Plant Growth. Edited "by Byron T.Shaw. Academic Press, Inc. 1952*

30. Miller, E, C. Plant Physiology. McGraw-Hill Book Co., Inc.New York. 1938.

31 • Musser, H. B. Turf Management. McGraw-Hill Book Co., Inc. 1951.

32* Nelson, ¥. L. and Baver, L. D. Movement of water through soils inrelation to the nature of the pores. Soil Sci. Soc. Am. Proc.5:69-76. 19*1-0.

33• Page, J. B. and Bodman, G. B. The effect of the soil physicalproperties on nutrient availability, 133-166. Mineral lutri-tion of Plants. The University of Wisconsin Press. 1951*

$k. Peterson, J. B. Relations of soil air to roots as factors inplant growth. Soil Sci. 70:175-186. 1950.

35• Proctor, R. R. Fundamental principles of soil compaction. II*Description of field and laboratory methods. Eng. News-Record.

^ ^ 1933*

36. Richards, L. A. and Wadleigh, C. H. Soil water and plant growth,7^-252. Vol. II. Soil Physical Conditions and Plant Growth.Edited "by Byron T. Shaw. Academic Press, Inc. Hew York.1952.

37* Richards, S. J., Hagan, R. M*, and McCalla, T* M. Soil tempera-ture and plant growth, 303-480. Vol.4-H. Soil PhysicalConditions and Plant Growth. Edited "by Byron T. Shaw. Aca-demic Press, Inc. Hew York. 1952.

38» Russell, M. B# Methods of measuring soil structure and aeration.Soil Sci. 68:25-35. ^

59

39* Russell, M. B. Soil aeration and plant growth, 25^-302.Vol. II. Soil Physical Conditions and Plant Growth.Edited "by Byron T. Shaw* Academic Press, Inc. HewYork,, 1952.

ho. Smith, F. W. and Cook, R, L, The effect of soil aeration,moisture and compaction on nitrification and oxidationand growth of sugar "beets following corn and legumes inpot cultures. Soil Sei. Soc. Am* Proc. ^ ^ 6&6

kl0 Taubenhaus, J. J., Ezekial, W. H., and Rea, H. E. Strangula-tion of cotton rootso Plant Physio. 6:l6l-l66. 1931.

h2m Taylor, S. A. Oxygen diffusion in porous media as affected bycompaction and moisture content. Soil Sci. Soc. Am. Proc.

Turner, T. W. Studies of the mechanism of the physiologicaleffects of certain mineral salts in altering the ratio oftop growth to root growth in seed plants. Am. Jour. Bbt.

1 ¥ 6 1922.

kk. Veihmeyer, F. J. and Hendrickson, A. H. Soil density and rootpenetration. Soil Sci. 65;if87-493. ^8

Watson, J. R. Jr. Irrigation and compaction on established fair-way turf. PhD* Dissertation. Penna. State College. 1950*

Weaver, J. E. Investigations of the root habits of plants. Am.Jour. Bot. 12:502-510. 1925.

Yoder, R. A. A direct method of aggregate analysis of soilsand a study of erosion losses. Jour. Am. Soc. Agron*28:337-351. 1936*

60

APPEKDIX

6l

Table h. Grams of the oven-dried plant materials removed from the turfgrown on individual soil mixtures in the first clipping.Clipping date: June 9, 1955.

ParticleSize SoilMixtures

5-2 mm.

2-1 mm.

1—0 • 5 mm.

0.5-0.25 mm.

<§.25 mm.

Mixed

Mixed Non-compacted

Mixed

Replicationsof SoilMixtures

123

12

H

CM

CO

12

1

123

123

1

6-3-1

CO

OJ C

OVO

H

VO

...CO

CO

OJ

3.523.05

2.21*2.1*72.31

2.812.88

3.37

2.702.002.66

2.903.562.1*5

5-1*-!

1.97

Ratios*

7-2-1

2.302.902.50

3.152.72

SO

J C

OC

OO

O

OJ

OJ C

M

2.723.81*

2.1*0

2.1*22.672.1*7

2.2l*1.572.28

Other

l*-5-l

2.93

8.1-1

3.932.872.03

2.552.61*

2.6k2.652.1*5

2.332,83

2.53

3.382.803.09

2.1*23.282.58

Ratios*

3-6-1

3.20

8-i-i-l

2.133.103.72

3.002.17

2.902.592.37

2.703.00

2.88

3.012.6**3.71

2,783.273.96

2-7-1

3.10

0-9-1

2.953.352.53

2.003.011.82

9-0-1

2.1*2

*Ratios are given in the order of sand, clay soil, and peat.

62

Table 5« Grams of the oven-dried plant materials removed from the turfgrown on individual soil mixtures in the second clipping.Clipping date: July 21, 1955.

ParticleSize SoilMixtures

5-2 mm.

2-1 mm.

1-0.5 mm.

0.5-0.214- mm.

<$.25 mm.

Mixed

jmxed Non-compacted

Mixed

Replicationsof SoilMixtures

H

OJ

CO

12

123

12

1

123

123

1

6-3-1

1,81*1.731,22

2.1*1.89

1.801.581.73

I.851.95

1.85

2o331.832.1i-8

k.503.773^9

1.79

Ratios*

7-2-1

1.231.951.79

1.752.V7

2.071.75I.65

2.022.07

1.83

3.002.773.35

If. 20l*.083.32

Other

k-5-1

1.89

8-1-1

1.08.792M

2.6k

1.962.231.91

2.983.12

2.28

H

OJ

UNO

J OJ C—

...CO

CO

HI

3.89

4I36

Ratios*

3-6-1

1.50

8—-—-i

1.731.521.57

2.202.22

-2.352.772.71

2.992.53

2.27

2.213.823.60

U.80

3^X9

2-7-1

1.17

0-9-1

1.701.82.95

3.93

3.16

9-Q-l

3.23

* Ratios are given in the order of sand, clay soil, and peat.

Table 6. Grams of the oven-dried plant materials removed from the turfgrown on individual soil mixtures in the third clipping.Clipping date: November 22, 1955»

63

ParticleSize SoilMixtures

5~2 mm*

2-1 mm.

1-0.5 urau

0.5-0.25 mm.

<$.25 mm.

Mixed

Mixed Non-compacted

Replicationsof SoilMixtures

123

12

123

12

Ratios*

6-3-1

1.19.89.82

.78

2.102.221.57

1.231.30

1.672.712.33

1.27I.691.80

7-2-1

.92

.57

2.472.002.48

2.231.85

1.55 2.28

2.952.803.14

1.701.441.33

8-1-1

1.081.291.37

1.15.97

2.953.134.15

3.052.69

2.05

2.102.722.39

3.493.122.96

1.97.81.67

1.17• 77

3.002.081.51

57• 5 3

1.95

.26

.702.1*

2.352.353.58

0-9-1

578869

3.122.722.12

Mixed. 1.97

Other Ratios*

4-5-1 3-6-1

2.30 1.76

2-7-1 9-0-1

1.11 1.96

•Ratios are given in the order of sand, clay soil, and peat,

Table 7. Grams of the oven-dried plant materials removed from the turfgrown on individual soil mixtures in the fourth clippingoClipping date: April 20, 1956O

6k

ParticleSize SoilMixtures

5-2 mm.

2-1 mm.

1-0.5 ran.

0.5-0.25 mm.

<p.25 mm.

Mixed

Mixed Non-compacted

Replicationsof SoilMixtures

123

12

123

12

Ratios*

6-3-1 7-2-I 8-1-1

1.15I062I.63

1.252.19

3.^73.322.73

0970

2.229570

28

1.221.511.81

1.962.18

2.963-002A7

2.002.02

2.12

200007

1.75

I.832.20•72

.751.881.36

l.li-O2.00

2.862.952.98

2.222.20

2.523.052.82

3290

.53

70M

2.UO2.162.80

00

2.82

2.10

.25,80,60

,79,87

2.05.50

to,60M-75

Mixed

Other Ratios*

5-4-1 IJ-5-1 3-6-1 2-7-1

1.75 2o90 2.0*4- 2o30 2*77

* Ratios are given in the order of sand, clay soil, and peat,

Table 8. Grams of the oven-dried plant materials removed from the turfgrown on individual soil mixtures in the fifth clipping*Clipping date: May 10, 1956-

ParticleSize SoilMixtures

5-2 mm.

2—1 mm.

1-0.5 mm.

0.5-0.25 mm.

*sO.25 mm.

Mixed

Mixed Non-compacted

Mixed

Replicationsof SoilMixtures

123

12

123

12

1

123

123

1

6-3-1

1.561.091.50

.98

1.762.07

1 ^jk

1 2.k

2.03

1.76lo931.70

1.53I.651.59

5-*-l

1.37

Ratios*

7.-2-1

1.291.391.38

1.11

2A81.9*2.16

l.*91.26

lo58

2.272o222.25

I.691.661.19

Other

k-5-1

2.06

8-1-1

1.1*1.161.70

.961.16

1.9*1.922.90

1.60I.36

I.65

2.232.602.17

1.691.7*1.23

• Ratios*

3-6-1

1.10

8J-H.82.80

1.21.86

2.212.1*O2.6*

1.251.86

1.68

2.*72.561*98

I.78

1.90

2-7-1

I.76

0-9-1

1»371.231.19

2.583.072.31

9-0-1

1.58

* Ratios are given in the order of sand, clay soil, a M peat,

Table 9« Grams of the oven-dried plant materials removed from the turfgrown on individual soil mixtures in the sixth clipping.Clipping date: June 2, 1956.

66

Particle Replications Ratios*Size SoilMixtures

5-2 mm.

2-1 mm.

1-0.5 mm.

0.5-0.25 mm.

<£).25 mm.

Mixed

Mixed Non-compacted

of SoilMixtures

123

12

123

12

1

123

123

6-3-I

2.112.122.77

2.223.62

2.553.193.42

3.202.57

3.17

3.443.703.16

OJ O

HUN

00 UN

• •

•CO

OJ O

O

7-2-1

1.932.423.27

3.103.06

3.643.673.54

3.622.73

2.59

3.593.424.48

3.863.282.99

Other

8-1-1

1.861.372.26

2.662.25

3.373.754.18

3.673.01

2.43

4.445.863.72

3.073.253.74

Ratios*

8--I.-1

1.261.722.30

2.782.88

4.724.114.04

3.363.16

2.08

4.525.204.61

3.192.843.44

0-

344

554

9-1

.77

.53

.18

.20

.25

.97

Mixed

^ 4-5-1 3-6-1 2-7-1 9-0-1

3.33 4.33 3.96 3.59 3.92

* Ratios are tiven in the order of sand, clay soil, and peat,

Table 10. Grams of tlie OTen-dried roots removed from the undisturbedsoil core samples taken from the individual soil mixtures.

67

ParticleSize SoilMixtures

5-2 ram.

2—1 mm.

1—0.5 mm.

0.5-0.25 mm.

<b.25 mm.

Mixed

Mixed Non-compacted

Replicationsof SoilMixtures

123

12

H

OJ CO

12

1

123

H

OJ CO

6-3-1

3.362.922.11

1.90

2.381.912.13

2.703.30

1**21

I0671.73

1.882.021.82

Ratios*

7-2-1

1.662.51

2.211.67

2.823.071.89

2.7**2.76

3.19

2.032.2**2.86

2.932.503.27

Othea

8-1-1

3.311.712.61*

2.502.99

3.191.60

2.712.61*

l*.05

3.292.5I*Io92

2.702.331.79

? Ratios*

8H-1

2.252.1*11.33

1.931.89

1.552.751.93

2.962.91*

2.60

2.501.002.21

1.302.12

0-9-1

CO lf\C

OCO

OO

OO

OO

H

H

1.722.092.90

jMixed

3-6-1 2-7-1 9-0-1

2.35 3.08 2.63 2.38 2.37

* Ratios are given in the order of sand, clay soil, and peat.

Ta*ble 11. Grams of the total oven-dried roots removed from theindividual soil mixtures.

68

PartieleSize SoilMixtures

5-2 mm.

2-1 mm.

1—0.5 mm.

O.5-O.25 mm.

<0.25 mm.

Mixed

Mixed Non-compacted

Replicationsof Soi lMixtures

123

12

123

12

1

123

123

6-3-1

2k&628.2825.83

25.1827.27

2k.622k.&(27.89

28.2k26.05

30.59

2k.0923.59

23I&25.30

Ratios*

7—2—1

25.6925.2527.^0

27.9526.16

25.6727.9627.98

30.1333.98

30.98

20.1720.2825.36

22.7023.7122 .kk

Othes

8-1-1

27*732^.65

29I75

27.3530.9527.30

27.2328.72

32.06

26.1223.59

30.3821.18

: Ratios*

8^-1

1818825.21

27.0725.28

26.6625.0528 A6

26.k2

33.7^

22.3527.912^.29

26.39

26.17

0-9-1

22.6620.6021.62

26.8929.6727.75

Mixed 27.86 29.26 29.25 2T(.2k 25.29

* Ratios are given in the order of sand, clay soil, and peat.

Ta"ble 12. Percent non-capillary, pore space in the undisturbed soilcore samples taken from the individual soil mixtures.

69

ParticleSize SoilMixtures

5-2 mm»

2—1 mm*

1-0.5

05.-0.25 mm.

<0.25 mm.

Mixed

Mixedcompacted

Replicationsof SoilMixtures

123

12

123

12

123

123

Ratios*

6-3-1

9.712.313.0

7.89.1

5.8

3.93.9

3.9

3.93.25.2

18.818.817.5

lfc.916.22k .3

13.015.6

7.86.57.1

7.1

3.2

Q.k7.87.8

17.5

18.2

8-1-1

15.613.616.2

16.916.2

12.311.712.3

9.110 .k

3.2

9.111.79.1

18.220.117.5

17.517.513.0

18.217.5

13.015.615.6

10. k12.3

3.9

13.013.09.7

20.121.1*16.9

0-9-1

5.25.25.8

15.6

Mixed 5.2

Other Ratios*

-5-1 3-6-1

6.5 5.8

2-7-1 9-0-1

5i8 13.O

* Ratios are given in the order of sand, clay soil, and peat.

70

!Eable 13. Percent capillary pore space in the undisturbed soil coresamples taken from the individual soil mixtures.

ParticleSize SoilMixtures

5°2 mm.

2—1 mm.

x«~u.p mm.

O.5-O.25 mm.

<0.25 mm.

Mixed

Mixed Non-compacted

Mixed

Replicationsof SoilMixtures

123

12

123

12

1H

C

M C

OH

C

M C

O

1

6-3.-1

31.129.230.5

29.229.8

30.531.130.5

33.731.8

35.0

31.1

30.5

26.629.827.9

5 ^ 1

35.7

Ratios*

7_-2"l

26.62k.627.2

26.625.9

31.131.131.8

29.225.9

35.0

30.529.832.^

27.925.927.9

Other

t-5-1

37.0

8-1-1

2^.029.825.3

cocoft

0C

OlfN

CM C

M

25.929.825.3

27.227.9

37.0

29.826.627.9

2^.022.722.0

Ratios*

3-6-1

to.8

8^4-1

20.722.02^.0

0 0

CM C

MCM

CM

25.3

23.3

27.231.1

35.0

27.222.026.6

2^.0

23.3

2-7-1

to.8

0-9-1

53.25^.552.5

lj-8.651.950.6

9-0-1

22.0

* Ratios are given in the order of sand, clay soil, and peat.

fable 1%. Percent total pore space in the undisturbed soil coresamples taken from the individual soil mixtures.

71

ParticleSize SoilMixtures

5—2 mm.

2—1 mm.

1.0.5 - .

O.5-O.25 mm.

<b.25 mm.

Mixed

Mixed Non-compacted

Replicationsof SoilMixtures

123

12

123

12

1

123

123

6-3-1

1*1.91*1.5

37.038.9

36.335.635.0

37.635.7

38.9

35.035.635.7

1*8̂ 61*5.1*

Ratios*

7-2-1

1*1.5to.81*1.5

39.6

38.937.638.9

33.733.0

38.2

38.937.61*0,2

l*6!l

8-1-1

39.6

to.21*1.5

38.21*1.537.6

36.938.3

to.2

38.938.337.0

1*2.21*2.839.5

Other Ratios*

38.239.537.0

to.239.5

CO

VO

O

N«

0 «

CO

O

NC

OC

O C

O C

O

37.61*3.1*

38.9

to.235.036.3

to.8to.2

0-9-1

58.1*59.758.3

68.067.5

•Mixed

fr-5-1 3-6-1 2-7-1 9-0-1

to.9 U3.5 i^.6 1*6.6 35.0

* Ratios are given in the order of sand, clay soil, and peat.

Table 15* Bulk density measurements (in grams per cubic centimeter)of the undisturbed soil core samples taken from the indi-vidual soil mixtures.

72

ParticleSize SoilMixtures

5-2 mm.

2-1 mm.

1-0.5 mm.

0.5-0.25 mm.

<0.25 mm.

Mixed

Mixed Non-compacted

Replicationsof SoilMixtures

123

12

123

12

1

123

123

6-3-1

1.591.571.55

I.69I.63

1.661.691.66

1.621.65

1.55

1.671.671.69

1I39

Ratios*

7-2-1

1.561.581.56

1.631.59

1.611.591.61

1.6k1.65

1.60

1.66I.69l.ol

1 kQ1.50l.kQ

Othei

8-1-1

1.581.571.51

1.59

I.651.531.59

1.611.56

1.50

1.591.601.6k

1.511.521.58

? Ratios*

8J-H1.62I.581.68

1.581.61

I.63

ll57

1.551.51

1.57

1.591.711.66

1.501.571.59

0-9-1

1.17l.lfc1.13

.86

.91

.93

Mixed 1.55 1.51

3-6-1 2-7-1 9-0-1

1A3 l.kS 1.69

* Ratios are given in the order of sand, clay soil, and peat,

Table 16. Permeability measurements (in inches per hour) of theundisturbed soil core samples taken from the individualsoil mixtures «**

73

ParticleSize SoilMixtures

5-2 ma.

2—1 mm.

1-0.5 mm.

0.5-0.25 mm.

<0.25 mm.

Mixed

Mixed Hon-compacted

Replicationsof Soil^fixtures

123

12

H

OJ C

O12

1

123

123

6-3-1

.02

.11

.22

.12

.18

.01

.02

.02

.02

.01

.01

.01

.01

.01

•31.51.1*0

Ratios*

7-2-1

.02

.06

.06

.53

.7*

.13

.09

.09

.05

.08

.08

•06.06.ok

M•97

8-1-1

*251.07

1.38.72

.12

.23

.27

.07•10

.07

.25

.19M.60.66

Other Ratios*

8^-1

.16

.23•63

1.56

.23

.27M.11.09

.02

.27

.72

.12

.37

.37

.19

0-9-1

.01

.01

.01

.93

.7*

.58

Mixed

5-4-1 k-5'1 3-6-1 2-7-1 9-0-1

.01 .01 .01 .01 .35

* Ratios are given in the order of sand, clay soil, and peat.

** Core dimensions: diameter - 2 inches, height - 3 inches. .Headmaintained at -J- inch.

Table 17* Percent of aggregate sizes in various ratios of the mixedparticle size soil mixtures.

Soil MoistureTreatment

Non-compacted

Compacted

Non-compacted

Compacted

Non-compacted

Compacted

Non-compacted

Compacted

Non-compacted

Compacted

Number ofAnalyses

12

12

12

12

12

12

12

12

12

12

>2 mm.

0-9-1

67.^1

29.6029.82

6-3-1

k.062.81

1.502.37

7-2-1

1.102.5k

2.10

8-1-1

.751.23

1.371.57C% x jL *i

1.371.51

I.09.95

>1 mm.

Ratio*

20.9012.00

21.5118.66

Ratio*

k.lkh.22

Ratio*

1.272.91

l!o5

Ratio*

1.391.71

ll69

Ratio*

.81I.69

2.92.99

Aggregate>0*5 mm.

^•17

6.7k9.53

2.631.88

1.251.23

2.021.90

.77

1.311.21

1.031.98

.68

.62

.601.07

Size

8.00^.50

X3.O3

8.758.25

5.567.3^

8.565.85

5.816.92

5.607.06

5.185.56

is6.635.1^

^0*1 mm.

iJko1.21

5»131^67

2.322.77

.77

.63

1.53.83

•38.73

1*67

.12••30

X.31

* Ratios are given in the order of sand, clay soil, and peat.

75

Table 18. Percent of aggregate sizes in various particle size6-3-1 soil mixtures.

Number ofAnalryses

123k

123k

> 2 mm.

8.918.1*33.89k.lh

^.556.933.703.60

> 1 mm.

5-2 mm.

5l776.2k6.87

2 - 1 mm.

5.59k.026.225.98

Aggregate>0.5 mm.

Mixtures

2.201.5^2.151.95

Mixtures

2.263.371.99

Size>0.25 mm.

3.293.273.50^.27

5.795.735.654.92

^ ^ 0 . 1 mm.

1M1.161.161.81

2.762.5^2.302.M

1-0.5 rani. Mixtures

l23k

.971.052.111A7

2.895.935.612.2l|-

3.012.762.071.99

5.937.935.986.10

3.501.71

H 2 ^

0.5-0.25 mm. Mixtures

123k

1.10.81

1.101.10

1.5^1I26l . i j -2

1.63

2.031.18I0871.3^

9.6711.5^7.^09.72

3.29fy.ll6.065.12